Checkride Week 4: Tasks D + E + F

Tasks D, E and F of the checkride are Cross-Country Flight Planning, National Airspace System, and Performance and Limitations. All three sit in Area of Operation I, Preflight Preparation. The evaluator covers all three in one session, because all three apply to one flight:

• Task D covers the route you plan and the numbers you computed
• Task E covers the airspace the route crosses and the requirement of each class
• Task F covers whether the airplane can fly the route on this day at this weight.

PA.I.D.S1 sets the work the applicant brings to the checkride. It requires the applicant to "Prepare, present, and explain a cross-country flight plan assigned by the evaluator, including a risk analysis based on real-time weather, to the first fuel stop" 1. The evaluator assigns the route days before. The plan is the evidence for most of Task D and much of Tasks E and F.

Task D lists six knowledge elements, seven risk management elements and five skill elements. Its Note allows a computer-generated flight plan 1. Task E lists four knowledge elements, one risk management element and three skill elements 2. Task F lists three knowledge elements, three risk management elements and two skill elements, and its K2 carries six sub-elements 3.

The three Tasks name these references:

• 14 CFR parts 71, 91 and 93
• the Aeronautical Information Manual
• the Chart Supplements and the VFR navigation charts
• NOTAMs
• FAA-H-8083-1, the Aircraft Weight and Balance Handbook
• FAA-H-8083-2, the Risk Management Handbook
• FAA-H-8083-3, the Airplane Flying Handbook
• FAA-H-8083-25, the Pilot's Handbook of Aeronautical Knowledge
• the POH or AFM for the airplane you bring.

Area of Operation VI, Navigation, uses the same plan. The evaluator flies the route you planned. Tasks VI.A, VI.B and VI.D grade three parts of that flying 4 5 6:

• pilotage and dead reckoning
• navigation systems and radar services
• lost procedures. The oral covers their knowledge elements on the same day as Task D, because the plan and the flying of it are one subject.

14 CFR 91.103 is the regulation Task D tests. It says that "Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight" 7. The rule then names what the information must include, and it splits the list in two. Paragraph (a) applies to a flight under IFR or a flight not in the vicinity of an airport. Paragraph (b) applies to any flight.

Paragraph (a) names four items 8:

• weather reports and forecasts
• fuel requirements
• alternatives available if the planned flight cannot be completed
• any known traffic delays of which the pilot in command has been advised by ATC.

Each item in that list is a separate question on the oral. Weather reports and forecasts is Task C, asked the week before. Fuel requirements is PA.I.D.K3c. Alternatives available is PA.I.D.R4, external pressures, because an alternative arranged before takeoff is what removes the pressure to continue. Known traffic delays comes from ATC and belongs to PA.I.D.R5.

Paragraph (b) applies to each flight, including one circuit of the traffic pattern. It names "runway lengths at airports of intended use, and the following takeoff and landing distance information" 8. Where an approved flight manual carrying takeoff and landing distance data is required, that manual holds the data. For a civil airplane with no such manual, the rule accepts "other reliable information appropriate to the aircraft, relating to aircraft performance under expected values of airport elevation and runway slope, aircraft gross weight, and wind and temperature". Paragraph (b) requires the takeoff and landing performance data that Task F covers.

NOTAMs are part of all available information. A temporary flight restriction is issued as a NOTAM, and the AIM states that temporary flight restrictions "restrict entrance to a certain airspace at a certain time, however, some TFRs provide relief if ATC permission is given to enter the area when requested" 9. The NOTAM check is therefore an airspace check as well as a runway check. An evaluator who asks how you found a TFR is asking a Task D question and a Task E question at once.

The VFR sectional chart is the planning chart for a private pilot cross-country. The handbook describes the scale: "Sectional charts are the most common charts used by pilots today. The charts have a scale of 1:500,000 (1 inch = 6.86 nautical miles (NM) or approximately 8 statute miles (SM)), which allows for more detailed information to be included on the chart" 10. The Chart Users' Guide adds that "Sectionals are named after a major city within its area of coverage" 11.

Sectional charts change on a 56-day cycle. The Chart Users' Guide states that "These charts are updated every 56 days" 11. The handbook's older sentence about semiannual revision is out of date. A chart older than the current edition can omit a new tower, a changed frequency, or new airspace. The pilot checks the edition date before drawing the course line.

Route selection starts with the airspace the route crosses. The handbook works an example and names what the check finds: "The course and areas on either side of the planned route should be checked to determine if there is any type of airspace with which the pilot should be concerned or which has special operational requirements" 12. Its example course crosses a Class C shelf with a floor at 2,500 feet MSL. It also crosses a Class D that reaches 3,800 feet MSL while the tower operates. Class B, Class C and Class D each add a communication or clearance requirement. The pilot identifies special use airspace and checks its status.

The Chart Supplement holds the airport detail that the chart does not print. The handbook lists it: "location, elevation, runway and lighting facilities, available services, availability of aeronautical advisory station frequency (UNICOM), types of fuel available (use to decide on refueling stops), FSS located on the airport, control tower and ground control frequencies, traffic information, remarks, and other pertinent information" 13. It also tells the pilot to read the current NOTAMs with it. Where the Chart Supplement and the information on the back of the chart disagree, the Chart Supplement applies.

Route selection also considers the terrain under the route. The handbook's enVironment questions ask the pilot to "Choose the flight route wisely. An engine failure gives the nearby airports supreme importance" 14. The pilot weighs terrain, the airports along the route, and glide range against the shortest straight line. The shortest line is rarely the route flown on the checkride. An applicant who states why he moved the course line answers PA.I.D.R3 before the evaluator asks it.

An electronic flight bag can replace paper charts for VFR flight under four conditions. AC 91-78A states that an EFB can be used "in lieu of paper reference material when the information displayed meets the following criteria" 15:

• the EFB system does not replace any system or equipment required by part 91
• it displays only information functionally equivalent to the paper it replaces
• the information used for navigation or performance planning is current, up to date, and valid, as verified by the pilot
• the operator complies with 14 CFR 91.21 so the EFB does not interfere with required equipment.

The third condition is the one an evaluator tests. The pilot verifies currency. A chart database that expired two weeks ago fails the condition, and the pilot, not the application, is the one who checks it.

PA.I.D.R7 covers the plan for an EFB failure. The advisory circular names what the assessment covers: "workload, integration of the EFB into the flight deck, display and lighting issues, system shutdown, and system failures" 16. It adds the physical questions of stowage during takeoff and landing and of an unsecured device. A useful answer names three items:

• the charge state of the device at engine start
• the backup device or paper chart on board
• the thermal shutdown of a tablet in direct sun.

Cruising altitude clears the terrain and the obstacles under the whole route. The sectional prints a Maximum Elevation Figure in each quadrangle. The Chart Users' Guide defines it: "The Maximum Elevation Figure (MEF) represents the highest elevation within a quadrant, including terrain and other vertical obstacles (towers, trees, etc.)" 17. The ticked lines at each 30 minutes of latitude and longitude bound a quadrangle. The chart rounds the figure up to the next hundred feet and omits the last two digits.

The MEF is not a safe cruising altitude on its own. Its allowances cover the chart's own error. The guide lists them as the source's possible vertical error and "a 200' allowance for uncharted natural or manmade obstacles", and it warns that "while the MEF is based on the best information available to the Specialist, the figures are not verified by field surveys" 17. The pilot adds a clearance margin above the MEF, and that margin is the pilot's number, not the chart's.

Glide range increases with altitude. The Airplane Flying Handbook gives the first action after an engine failure at night: "Maintain positive control of the airplane and establish the best glide configuration and airspeed. Turn the airplane towards an airport or away from congested areas" 18. Turning toward an airport requires an airport inside the glide, and the glide distance grows with height. A higher cruise altitude puts more landable ground and more airports inside the glide range.

14 CFR 91.159 sets the cruising altitude. It applies to a person "operating an aircraft under VFR in level cruising flight more than 3,000 feet above the surface", and it yields to an ATC authorization 19. Below 18,000 feet MSL it gives two cases. A magnetic course of zero degrees through 179 degrees takes "any odd thousand foot MSL altitude + 500 feet (such as 3,500, 5,500, or 7,500)". A magnetic course of 180 degrees through 359 degrees takes "any even thousand foot MSL altitude + 500 feet (such as 4,500, 6,500, or 8,500)".

The rule applies under three conditions. The flight is in level cruise, it is more than 3,000 feet above the surface, and it is VFR. The rule does not apply to a climb, and it does not apply to a cruise 2,500 feet above the ground. The altitudes are MSL and the surface is the ground below. Rising terrain can therefore bring a cruise altitude under the rule partway along a leg.

The rule applies to magnetic course. Course is the line on the chart corrected for variation. Heading is the course corrected for wind. A wind correction angle of 12 degrees to the right changes the heading you fly and changes nothing about which altitudes are legal. An evaluator who gives a course of 178 degrees and a heading of 190 degrees tests that point. The answer is an odd thousand foot MSL altitude plus 500 feet.

Time en route for a leg is the leg distance divided by the groundspeed. The handbook works it: "If the distance measures 220 NM, divide by the GS of 88 knots, which gives 2.5 hours, or 2:30, as the time required" 20. Each other number on the nav log depends on the time en route. Fuel is the time multiplied by a rate. The estimated time of arrival is a clock time plus the time en route.

Groundspeed is true airspeed corrected for wind. The handbook gives the arithmetic with an airplane at 120 knots. A 20-knot tailwind makes the groundspeed 140 knots. A 20-knot headwind makes it 100 knots 21. The airspeed does not change in either case. Only the progress over the ground changes. The wind does not change the airspeed indication, and it does change the fuel required.

Flight plan times and estimates are in Coordinated Universal Time. The AIM states that "FAA uses Coordinated Universal Time (UTC) for all operations". It adds that "The word "local" or the time zone equivalent must be used to denote local when local time is given during radio and telephone communications", and that "The term "Zulu" may be used to denote UTC" 22. Local time converts by the zone offset. The date changes when the conversion crosses midnight Zulu. An evening flight in the western United States crosses it.

Leg fuel is the leg time multiplied by the fuel rate for the power setting you plan to fly. The Warrior's cruise performance chart gives three rates: "75% POWER 9.2 GPH. 65% POWER 8.0 GPH. 55% POWER 6.7 GPH", leaned per Lycoming instructions 23. The rate belongs to the power setting, so the pilot chooses the power setting before computing the fuel. A plan at 75 percent power and a flight at 65 percent produce different times and different fuel burns.

Total fuel is more than the cruise legs. The handbook names the parts: "When estimating consumption you must plan for cruise flight as well as startup and taxi, and higher fuel burn during climb" 24. It adds that the reserve goes on top of the total. The handbook names four of the parts, and North Aero planning adds the descent, so the full sum runs to five:

• taxi and run-up
• the climb
• each cruise leg
• the descent
• the reserve.

14 CFR 91.151(a) sets the legal reserve. It states that no person can begin a flight in an airplane under VFR conditions without enough fuel for two parts 25. The first part is the fuel to fly to the first point of intended landing, with wind and forecast weather counted. The second part is fuel to fly for at least 30 minutes after that point at normal cruising speed during the day. At night the figure is 45 minutes. Two conditions in the rule set the measurement. The reserve is measured at normal cruising speed, not at an economy setting. The wind and the forecast are counted in the fuel to the first point of intended landing.

Usable fuel is the planning number. The Warrior's manual gives both figures: "Fuel is stored in two twenty-five gallon (24 gallons usable) fuel tanks, giving the airplane a total capacity of fifty U.S. gallons (48 gallons usable)" 26. The two-gallon difference is fuel the tank holds and the engine cannot reliably draw in flight attitudes. A fuel plan built on 50 gallons in a Warrior overstates the usable fuel by two gallons.

The 91.151 reserve is a legal minimum. The Risk Management Handbook states the gap: "Federal regulations that apply to aviation do not cover every situation nor do they guarantee safety", and it recommends "non-mandatory self-regulation in the form of personal minimums" that "are more restrictive than the regulatory requirements" 27. North Aero planning sets a personal fuel reserve larger than 30 minutes, and sets it before the flight. The handbook gives the reason for writing it down: "Established personal minimums enable the pilot to make a no-go or divert decision rather than departing with a sense of unease regarding the outcome of a flight."

A fuel decision point is a named place on the route. The pilot chooses it before takeoff, with the fuel figure the airplane must have at that point. If the fuel is below plan at that point, the flight lands and refuels. The pilot makes the decision on the ground with a chart and a calculator. The pilot does not reopen it in flight 40 miles from the destination.

An NTSB report gives the arithmetic of a fuel plan the pilot never revised. A Cessna 150M left with 22.5 usable gallons. The report's calculation, run on the POH performance data at the flown altitudes and the computed winds, found "the airplane would have had an endurance of about 3.75 hours with full fuel tanks", and "The data showed that the airplane was airborne about 4 hours" 28. The pilot diverted for cheaper fuel 40 nautical miles short of the destination, overshot the final approach, and lost all engine power while circling. The probable cause was "The pilots' inadequate preflight fuel planning and in-flight fuel management, which resulted in a total loss of engine power due to fuel exhaustion."

A VFR flight plan exists for search and rescue. The AIM states that "Activating the flight plan will ensure that you receive VFR Search and Rescue services" 29. The plan tells Flight Service the route, the airplane, the people on board, and the hour at which a search starts. It provides nothing else. It gives no clearance, no traffic advisory, and no priority.

Filing is not required for most VFR flights. The AIM states that "Within the continental U.S., a VFR flight plan is not normally required", and then that "It is strongly recommended that a VFR flight plan be filed with a Flight Service Station or equivalent flight plan filing service" 29. The form is FAA Form 7233-4, the International Flight Plan. The pilot can file by any available electronic means.

Filing does not activate the plan. The AIM tells pilots to activate "by the most expeditious means possible", by radio or other electronic means, and states that "U.S. air traffic control towers do not routinely activate VFR flight plans" 29. The AIM states that "VFR flight plan proposals are normally retained for two hours following the proposed time of departure" 29. An assumed departure time opens the plan at the designated time without a call, and the AIM warns that "If not updated, search and rescue activities will be based on the assumed departure time" 30.

Closing the plan is the pilot's job. The AIM states that "A pilot is responsible for ensuring that his/her VFR or DVFR flight plan is canceled", and that "Control towers do not automatically close VFR or DVFR flight plans since they do not know if a particular VFR aircraft is on a flight plan" 31. The consequence follows in the same paragraph: "If you fail to report or cancel your flight plan within 1/2 hour after your ETA, search and rescue procedures are started." Search and rescue procedures start 30 minutes after the estimated time of arrival on an open plan.

An interceptor rocking its wings means one thing. The AIM's signal table gives the day signal as "Rocking wings from a position slightly above and ahead of, and normally to the left of, the intercepted aircraft and, after acknowledgement, a slow level turn, normally to the left, on to the desired heading", and gives its meaning as "You have been intercepted. Follow me" 32. The intercepted pilot answers by rocking the wings and following the interceptor. At night the interceptor adds flashing navigation lights at irregular intervals.

The AIM lists three actions for an intercepted airplane, to be taken without delay 33:

• adhere to the instructions relayed by visual devices, visual signals, and radio from the intercepting aircraft
• attempt radio contact with the interceptor or with the appropriate air traffic control facility on 121.5 MHz or 243.0 MHz, giving identity, position, and nature of the flight
• select Mode 3/A code 7700 if transponder equipped, unless air traffic control instructs otherwise.

The AIM also states the consequence of noncompliance: "Noncompliance may result in the use of force" 33. The first two actions are compliance with the interceptor's signals and a call on 121.5 MHz. The common cause for a private pilot is an unchecked temporary flight restriction, and the preflight NOTAM check is what prevents the interception.

PA.I.D.R1 through R4 are the four PAVE categories applied to a cross-country flight. The handbook's Pilot question is "Am I ready for this trip?" asked "in terms of experience, recency, currency, physical, and emotional condition" 34. A four-hour trip adds duration to each of those. A local flight does not test three of these parts:

• fatigue at hour four
• food and water on board
• currency for the conditions at the destination.

The Aircraft question asks what the airplane imposes on this trip. The handbook lists the questions 35:

• is this airplane equipped for the flight, with instruments, lights, and adequate navigation and communication equipment
• can this airplane use the runways available for the trip with an adequate margin of safety
• can this airplane carry the planned load
• can this airplane operate at the altitudes needed for the trip
• does this airplane have sufficient fuel capacity, with reserves, for the trip legs planned.

The pilot asks the enVironment question leg by leg. The handbook names these checks 14:

• NOTAMs for closed runways and airports
• a route that keeps an airport within glide range after an engine failure
• shorter or obstructed fields at the destination and the alternate
• "the airspace and any temporary flight restriction (TFRs) along the route of flight". Departure weather and destination weather do not cover the middle of a 200-mile route. Terrain, airspace and obstacles change between the endpoints.

External pressure can cause a pilot to ignore the other three categories. The handbook states that "Management of external pressure is the single most important key to risk management because it is the one risk factor category that can cause a pilot to ignore all the other risk factors" 36. A reason you must arrive is itself a risk factor. The pilot arranges the mitigation before takeoff:

• time in the trip for an extra fuel stop or an unexpected landing
• alternate plans for a late arrival, or a backup airline reservation
• a planned alternate.

VFR flight following is provided when workload permits. The AIM describes radar traffic information service and then limits it: "Many factors, such as limitations of the radar, volume of traffic, controller workload and communications frequency congestion, could prevent the controller from providing this service. Controllers possess complete discretion for determining whether they are able to provide or continue to provide this service in a specific case" 37. Radar coverage and radio coverage each have a lower altitude limit, and a flight low over terrain can lose both. A controller can refuse the service at the start and can terminate it in the middle.

No ATC service removes the pilot's duty to see and avoid. 14 CFR 91.113(b) states that "When weather conditions permit, regardless of whether an operation is conducted under instrument flight rules or visual flight rules, vigilance shall be maintained by each person operating an aircraft so as to see and avoid other aircraft" 38. The AIM says the same of flight following: the service "is not intended to relieve the pilot of the responsibility for continual vigilance to see and avoid other aircraft" 37. Terrain avoidance and airspace compliance stay with the pilot in command for the same reason.

Pilotage is navigation by visible landmarks compared against the chart. The handbook names it as one of three methods, defining pilotage as "navigating by reference to visible landmarks", dead reckoning as "computations of direction and distance from a known position", and radio navigation as navigation "by use of radio aids" 39. Task A of Area VI grades the first two. Task B grades the third.

Dead reckoning is computation. The handbook defines it as "navigation solely by means of computations based on time, airspeed, distance, and direction", and names the two products: "The products derived from these variables, when adjusted by wind speed and velocity, are heading and GS" 40. The heading holds the intended path. The groundspeed sets the time to each checkpoint and to the destination.

The two methods run together on a cross-country. The handbook states the combination: "Except for flights over water, dead reckoning is usually used with pilotage for cross-country flying. The heading and GS, as calculated, is constantly monitored and corrected by pilotage as observed from checkpoints" 40. Dead reckoning predicts and pilotage confirms. A pilot who predicts and never confirms does not know whether the airplane is on course. A pilot who reads landmarks and never predicts does not know whether the airplane is late.

A regulation requires pilotage and dead reckoning in cross-country training. 14 CFR 61.93(e)(1) lists the first maneuver a student pilot must receive and log for cross-country training in a single-engine airplane: "Use of aeronautical charts for VFR navigation using pilotage and dead reckoning with the aid of a magnetic compass" 41. The rule names charts, pilotage, dead reckoning and the compass. It names no electronic navigation at all. Electronic navigation is an addition to pilotage and dead reckoning.

Variation is the angle between true north and magnetic north at your position. The handbook defines it and locates it on the chart: the amount and direction "are shown on most aeronautical charts as broken magenta lines called isogonic lines that connect points of equal magnetic variation" 42. A line of zero variation is the agonic line. On the west coast of the United States the compass needle points east of true north. On the east coast it points west of true north.

The direction of the variation sets whether the pilot adds it or subtracts it. The handbook's worked example applies it: variation of 6.30 degrees east, rounded to 7 degrees east, "means it should be subtracted from the TH, giving an MH of 21°" 43. Easterly variation is subtracted when converting from true to magnetic. Westerly variation is added.

The heading chain has four steps. The handbook gives the sequence: after the true course is measured and the wind correction is applied to give a true heading, "the sequence TH ± variation (V) = magnetic heading (MH) ± deviation (D) = compass heading (CH) is followed to arrive at compass heading" 43. Deviation comes from the compass correction card in the airplane. The example ends with 2 degrees added for deviation and a compass heading of 23 degrees.

The wind correction angle is the middle step. The handbook explains the geometry: "if the wind is from the left, the correction is made by pointing the aircraft to the left a certain number of degrees, therefore correcting for wind drift" 43. The angle is expressed in degrees right or left of the true course. The pilot turns the nose into the wind by the amount that keeps the ground track on the course line.

Contour lines and shaded relief show the terrain on a sectional. The Chart Users' Guide gives the intervals and the reading: "Widely spaced contours represent gentle slopes, while closely spaced contours represent steep slopes" 44. Basic contours are spaced at 500 feet on a sectional, with intermediate contours typically at 250 feet in gentler country. Shadows are drawn as if the light comes from the northwest.

The pilot chooses a checkpoint for what he can confirm at 140 miles an hour. The handbook names the kinds: "large towns, large lakes and rivers, or combinations of recognizable points, such as towns with an airport, towns with a network of highways, and railroads entering and departing" 45. It also names what to avoid: "Normally, choose only towns indicated by splashes of yellow on the chart. Do not choose towns represented by a small circle—these may turn out to be only a half-dozen houses." The pilot confirms a checkpoint on or near the course line without leaving the course.

Line features have two uses. A river, highway or railroad that crosses the course marks a time check, because the airplane passes it at a computed minute. A line feature running parallel to the course bounds the drift. The handbook describes the second use: "select features that make useful boundaries or brackets on each side of the course, such as highways, rivers, railroads, and mountains. A pilot can keep from drifting too far off course by referring to and not crossing the selected brackets" 46. It adds one rule for a missed checkpoint: "If confused, hold the heading."

True course is measured against a meridian near the midpoint of the leg. The handbook gives the reason: "Because meridians converge toward the poles, course measurement should be taken at a meridian near the midpoint of the course rather than at the point of departure" 47. The angle is read clockwise from true north with a plotter. The result is the true course, the first number in the heading chain.

True airspeed is calibrated airspeed corrected for density altitude. The handbook gives an approximation: "Simply add 2 percent to the CAS for each 1,000 feet of altitude", and states that "The TAS is the speed that is used for flight planning and is used when filing a flight plan" 48. The approximation is for a mental check. The planning number comes from the chart.

The Warrior's cruise performance chart gives true airspeed against density altitude for three power settings. Its title block reads "CRUISE PERFORMANCE - TRUE AIRSPEED. GROSS WEIGHT 2325 LBS. BEST POWER. MIXTURE—LEAN PER LYCOMING INSTRUCTIONS. WHEEL FAIRINGS ON", with curves for 55, 65 and 75 percent power and full throttle 49. A note subtracts 2 mph if the wheel fairings are not installed. The pilot enters the chart at the cruise density altitude and the chosen power setting, and reads the speed off the curve.

The wind side of the flight computer turns three inputs into two outputs. The handbook calls the method vector analysis: "A wind triangle, the pilot's version of vector analysis, is the basis of dead reckoning", and states that "The WCA can be determined by using a manual or electronic flight computer" 50. The three inputs are the forecast wind, the true airspeed, and the true course. The two outputs are the wind correction angle and the groundspeed.

Cruise power selection trades speed against fuel flow. The Warrior's range chart carries all three rates on one page: 9.2 gallons per hour at 75 percent power, 8.0 at 65 percent, and 6.7 at 55 percent, leaned per Lycoming instructions 23. The same chart plots range in statute miles against density altitude, with one line for no reserve and one for a 45-minute reserve. A higher power setting shortens the time en route and reduces the range.

The pilot measures the actual groundspeed in flight. The distance between two checkpoints divided by the time between them gives the current groundspeed of the airplane. The handbook's arithmetic works in that direction as well as the planning direction: 220 nautical miles divided by 88 knots gives 2.5 hours 20. Two checkpoints and a watch give the groundspeed that the wind forecast only predicted.

A groundspeed slower than planned changes the fuel required before it changes the arrival time. The handbook states the relation: "Since the rate of fuel consumption remains relatively constant at a given TAS, you must use GS to calculate fuel consumption when wind is present" 24. A groundspeed 10 percent below plan adds about 11 percent to the time and about 11 percent to the fuel. The pilot recomputes the fuel to the destination first and the arrival time second.

The pilot makes an off-course correction in two steps. The handbook warns against the one-step version: "Just turning toward the needle will cause overshooting the radial and flying an S turn to the left and right of course" 51. In the first step the pilot returns the airplane to the course line. In the second step the pilot holds a revised heading that keeps the airplane on the line, with a new wind correction angle.

A VOR broadcasts 360 radials referenced to magnetic north. The handbook defines one: "a radial is defined as a line of magnetic bearing extending outward from the VOR station", numbered from 001 through 360 52. A compass rose printed at the station on the chart shows their orientation. A radial always points away from the station, so an airplane on the 090 radial is east of the VOR whichever way it is flying.

The pilot identifies a VOR before using it. The AIM states that "The only positive method of identifying a VOR is by its Morse Code identification or by the recorded automatic voice identification which is always indicated by use of the word 'VOR' following the range's name" 53. A facility under maintenance "may radiate a T−E−S−T code or the code may be removed". No identifier means the facility is unusable, whatever the needle does.

The course selector and the flag give two different indications. The handbook describes the pair: the azimuth dial "can be rotated to select a desired radial or to determine the radial over which the aircraft is flying", and "the magnetic course 'TO' or 'FROM' the station can be determined" 54. The needle shows displacement from the selected course. The flag shows whether flying that course takes the airplane to the station or away from it.

Sensing depends on agreement between the selected course and the direction of flight. The handbook gives the rule: "When flying 'TO' a station, always fly the selected course with a 'TO' indication. When flying 'FROM' a station, always fly the selected course with a 'FROM' indication. If this is not done, the action of the course deviation needle is reversed" 51. Under reverse sensing a drift to the right moves the needle to the right. A pilot gets reverse sensing by flying the reciprocal of the selected course.

One VOR gives a line of position. Center the needle with a FROM indication, and the course window reads the radial the airplane is on 54. Two VORs give a point. The handbook lists the method among the lost procedures: "If the aircraft has a navigational radio, such as a VOR or ADF receiver, it can be possible to determine position by plotting an azimuth from two or more navigational facilities" 55. A two-station cross fix needs no landmark at all.

VOR reception is line of sight. The handbook gives the numbers: "its range varies in direct proportion to the altitude of receiving equipment. Generally, the reception range of the signals at an altitude of 1,000 feet above ground level (AGL) is about 40 to 45 miles. This distance increases with altitude" 52. Terrain between the airplane and the station blocks the signal. A VOR signal that is strong at 6,500 feet can be lost in a descent into a valley.

A GPS position comes from satellite ranging. The AIM gives the count: "The 24 satellite constellation is designed to ensure at least five satellites are always visible to a user worldwide. A minimum of four satellites is necessary for receivers to establish an accurate three−dimensional position" 56. Satellite status reaches pilots through the NOTAM system, which makes a GPS outage another item the preflight NOTAM check finds.

Receiver autonomous integrity monitoring is the receiver checking itself. The AIM defines it as "the capability of a GPS receiver to perform integrity monitoring on itself by ensuring available satellite signals meet the integrity requirements for a given phase of flight", and then states the consequence: "Without RAIM, the pilot has no assurance of the GPS position integrity" 57. Detection takes five satellites, or four with barometric aiding. Excluding a failed satellite takes six, or five with barometric aiding.

Two RAIM messages mean two different things. The AIM separates them: the first "indicates that there are not enough satellites available to provide RAIM integrity monitoring. The GPS navigation solution may be acceptable, but the integrity of the solution cannot be determined." The second "indicates that the RAIM integrity monitor has detected a potential error" 57. Either message means the position on the screen is unverified. The response is a cross-check against pilotage, dead reckoning or a VOR.

No regulation requires a current database for VFR. The AIM states it: "Databases must be updated for IFR operations and should be updated for all other operations. However, there is no requirement for databases to be updated for VFR navigation" 58. The handbook names what goes wrong anyway: an outdated moving map "may be outdated and offer erroneous information to VFR pilots wishing to fly around critical airspace areas, such as a Restricted Area or a Class B airspace segment. Numerous pilots have ventured into airspace they were trying to avoid by using an outdated database" 59. The pilot cross-checks an old database against a current chart, or disregards the moving map for critical navigation decisions.

Handheld and tablet receivers are aids, not primary navigation. The AIM states that "VFR GPS panel mount receivers and hand−held units have no RAIM alerting capability", that "No design standard of accuracy or integrity is used for a VFR GPS receiver", and it directs pilots, "Do not solely rely on GPS for VFR navigation" 58. The failure modes belong to the device. A battery discharges, a signal drops with no warning, and a hot cabin shuts the tablet off.

Flight following gives traffic advisories when workload permits. The AIM describes what a pilot receives: advice of "any radar target observed on the radar display which may be in such proximity to the position of their aircraft or its intended route of flight that it warrants their attention", and states that traffic information "may be provided to flights not operating on IFR flight plans when requested by pilots of such flights" 37. The request goes to approach control or to center with position, altitude and destination.

A controller gives the position of traffic as a clock position. The AIM lists four parts of an advisory 60:

• azimuth "in terms of the 12 hour clock"
• distance in nautical miles
• the direction the target is proceeding
• the type and altitude if known. The clock position refers to the ground track, not to the heading. The AIM's figure gives an example: "traffic information would be issued to the pilot of aircraft 'A' as 12 o'clock. The actual position of the traffic as seen by the pilot of aircraft 'A' would be 2 o'clock." A large wind correction angle moves the search sector by the same number of degrees.

A controller states the termination of radar service. The Pilot/Controller Glossary defines the phrase: "RADAR SERVICE TERMINATED− Used by ATC to inform a pilot that he/she will no longer be provided any of the services that could be received while in radar contact" 61. No handoff follows it. Navigation, terrain and traffic return to the pilot in command at that moment. The AIM also directs the pilot to advise the controller before leaving the frequency and then to set 1200 60.

A transponder has three modes. 14 CFR 91.215(b) describes each one:

• Mode A 4096 code capability replies "to Mode A interrogations with the code specified by ATC"
• Mode S adds replies to Mode S interrogations under TSO-C112
• Mode C is "automatic pressure altitude reporting equipment ... that automatically replies to Mode C interrogations by transmitting pressure altitude information in 100-foot increments" 62.

Mode A is the code. Mode C is the altitude. Mode S is the selective reply and the data link.

The code 1200 is VFR. Three codes are reserved: 7500 for hijack, 7600 for lost communications, and 7700 for emergency. The AIM gives the method for changing codes without transmitting a reserved code: "when switching from Code 2700 to Code 7200, switch first to 2200 then to 7200, NOT to 7700 and then 7200" 63. The same section notes that the encoder reports pressure altitude at the standard setting and the ground facility applies the local correction.

ADS-B Out broadcasts a satellite-derived position. The AIM describes the transmission: onboard avionics "determine the position of the aircraft by using the GNSS and transmit its position along with additional information about the aircraft to ground stations for use by ATC and other ADS−B services. This information is transmitted at a rate of approximately once per second" 64. It reaches the ground stations and the equipped airplanes around you.

ADS-B In is optional and it does not show everything. The AIM states the limit on traffic information service broadcast: "Only transponder−equipped targets (i.e., Mode A/C or Mode S transponders) are transmitted through the ATC ground system architecture", and "If there is no radar coverage in a given area, then there will be no TIS−B coverage in that area" 65. An airplane with no transponder is invisible to that service. A display with no targets does not mean there is no traffic.

An installed transponder must be turned on. 14 CFR 91.215(c) requires that in the airspace listed in paragraph (b) "or in all controlled airspace, each person operating an aircraft equipped with an operable ATC transponder maintained in accordance with § 91.413 shall operate the transponder, including Mode C equipment if installed, and shall reply on the appropriate code or as assigned by ATC" 66. The rule turns on the equipment installed and on being in controlled airspace, not on which class of controlled airspace it is. In Class E, a pilot with a working transponder operates it with altitude reporting.

The pilot programs the navigator before takeoff. The handbook states the rule and the error it prevents: "If navigating to user-defined waypoints, enter them prior to flight, not on the fly. Verify the planned flight against a current source, such as a current sectional chart. There have been cases in which one pilot used waypoints created by another pilot that were not where the pilot flying was expecting. This generally resulted in a navigation error" 67. A flight plan entered wrong and flown accurately takes the airplane off the intended route.

The pilot budgets head-down time. The handbook puts it two ways, once as "Minimize head-down time in the aircraft and maintain a sharp lookout for traffic, terrain, and obstacles", and once as "Just a few minutes of preparation and planning on the ground makes a great difference in the air" 67. Programming in flight takes attention away from flying the airplane and from looking outside. The order is to fly first and navigate second. The pilot chooses when to look down.

Each navigation source has a named limitation. A VOR is line of sight. A VFR GPS has no integrity alert. An electronic flight bag has a battery and a temperature limit. The handbook states the principle: "VFR pilots should never rely solely on one system of navigation. GPS navigation must be integrated with other forms of electronic navigation, as well as pilotage and dead reckoning" 68. The pilot names the limitation during planning, not after the display fails.

A lost signal has one first response. The handbook warns VFR pilots to "be prepared for intermittent loss of navigation signal, possibly with no RAIM warning to the pilot" 67. Say the loss out loud, so the next action is deliberate. Hold the last cross-checked heading. Rebuild the position from the nav log, the clock and the chart. That method is dead reckoning and pilotage.

The five Cs order the lost procedure: climb, communicate, confess, comply, conserve. The handbook supplies the steps, and the mnemonic is the school's ordering of them 55. The pilot flies the airplane first, before the first C. The pilot sets altitude and power and looks outside before the first radio call.

Climb is the first step for two reasons. The handbook gives both: "If a town or city cannot be seen, the first thing to do is climb, being mindful of traffic and weather conditions. An increase in altitude increases radio and navigation reception range and also increases radar coverage" 55. From a higher altitude the pilot sees more ground. A VOR, a controller, and a radar antenna that were below the horizon also come within range.

The pilot rebuilds the position from the last known fix. The time flown since that fix, multiplied by the groundspeed, gives the radius of the circle the airplane is inside. The pilot then matches large features inside that circle to the chart. The handbook adds a close-in method for a town: "If flying near a town or city, it may be possible to read the name of the town on a water tower" 55.

Two electronic methods need no landmark. The handbook names them: plotting an azimuth from two or more navigational facilities, and, "If GPS is installed, or a pilot has a portable aviation GPS on board", using it "to determine the position and the location of the nearest airport" 55. A two-VOR cross fix and a nearest-airport page both give the position by different means.

Any radar facility can find you. The AIM states the service: "Radar equipped ATC facilities can provide radar assistance and navigation service (vectors) to VFR aircraft in difficulty when the pilot can talk with the controller, and the aircraft is within radar coverage" 69. The handbook adds the frequencies and the fallback: communicate on a frequency shown on the sectional, and "If the situation becomes threatening, transmit the situation on the emergency frequency 121.5 MHz and set the transponder to 7700" 55. The AIM also states that the guidance is advisory and "the responsibility for flying the aircraft safely remains with the pilot" 69.

PA.VI.D.R3 names recording times over waypoints as a risk item. A nav log with actual times on it lets the pilot rebuild a position later. The handbook states the method: the computed heading and groundspeed "is constantly monitored and corrected by pilotage as observed from checkpoints" 40. A log filled in at each checkpoint gives a known fix and a known clock time. A blank log gives neither.

Doubt about position, fuel endurance or weather is already an urgency condition. The AIM sets the threshold: "An aircraft is in at least an urgency condition the moment the pilot becomes doubtful about position, fuel endurance, weather, or any other condition that could adversely affect flight safety. This is the time to ask for help, not after the situation has developed into a distress condition" 70. Fuel below plan, darkness approaching, or weather lowering each meet the definition on their own. The AIM adds the reason for speed: "Delay has caused accidents and cost lives."

A pilot who is lost flies the airplane first. The AIM tells pilots who become apprehensive to "request assistance immediately" rather than work the problem alone 70. The pilot sets a safe altitude and a cruise power setting, and keeps looking outside. An airplane circling a landmark flies an unpredictable track at low altitude. A pilot who reads a chart does not look for traffic.

The fuel log shows unplanned fuel consumption. A headwind stronger than forecast, a mixture left rich, and a deviation around weather each burn fuel the plan did not allocate. The handbook names the stopping rule: "You should always plan to be on the surface before ... Your flight time exceeds the amount of flight time you calculated for the consumption of your preflight fuel amount" 24. The checkpoint fuel log shows the overrun while fuel remains. The pilot then applies the fuel decision point set before takeoff.

Class A extends from 18,000 feet MSL up to and including flight level 600. The AIM defines it as "that airspace from 18,000 feet MSL up to and including FL 600, including the airspace overlying the waters within 12 nautical miles off the coast of the 48 contiguous States and Alaska" 71. The handbook gives the same limits 72. The airspace is not charted, because it is everywhere above 18,000 feet.

Class A is IFR only. 14 CFR 91.135 requires that "each person operating an aircraft in Class A airspace must conduct that operation under instrument flight rules (IFR)", with "Operations may be conducted only under an ATC clearance received prior to entering the airspace" 73. There is no VFR in Class A. A private pilot without an instrument rating cannot enter Class A.

The equipment rule comes from the same section. 14 CFR 91.135(c) requires the airplane to carry "the applicable equipment specified in § 91.215, and after January 1, 2020, § 91.225" 73. That equipment is a transponder with Mode C and ADS-B Out. Class A is the first of three airspace classes that require both.

Class B surrounds the busiest airports. The AIM describes it as "that airspace from the surface to 10,000 feet MSL surrounding the nation's busiest airports in terms of IFR operations or passenger enplanements", tailored individually, and built from "a surface area and two or more layers (some Class B airspace areas resemble upside-down wedding cakes)" 74. It is charted on the sectional, the terminal area chart, and the IFR en route low altitude chart.

Entry requires an ATC clearance. 14 CFR 91.131(a)(1) requires that "The operator must receive an ATC clearance from the ATC facility having jurisdiction for that area before operating an aircraft in that area" 75. The AIM repeats it and adds the weather: "Regardless of weather conditions, an ATC clearance is required prior to operating within Class B airspace" 76. Good weather changes nothing.

The clearance uses specific words. Two-way radio contact establishes entry into Class C and Class D. It does not establish entry into Class B. The words are "cleared into Class Bravo", and a controller who reads back your callsign and gives you a transponder code has not said them. An airplane that enters on a callsign alone has entered without a clearance.

The pilot requirement is a certificate. 14 CFR 91.131(b)(1) states that no person can take off or land at an airport within Class B, or operate within Class B, unless "The pilot in command holds at least a private pilot certificate". The rule lists three further alternatives, and the one a student uses is an airplane "operated by a student pilot who has met the requirements of § 61.94 or § 61.95 of this chapter, as applicable" 75. The rule then removes that exception at the busiest airports: at the airports listed in section 4 of appendix D, the PIC must hold at least a private pilot certificate.

The student endorsement under 61.95 carries three requirements. The rule requires ground and flight training from an authorized instructor "on that Class B airspace area", flight training received "in the specific Class B airspace area for which solo flight is authorized", and a logbook endorsement "dated within the 90-day period preceding the date of the flight in that Class B airspace area" 77. The endorsement names that airspace and no other. It expires after 90 days.

Class B equipment is three items. 14 CFR 91.131(c)(2) requires, for all operations, "An operable two-way radio capable of communications with ATC on appropriate frequencies for that Class B airspace area" 78. Paragraph (d) adds the transponder with automatic altitude reporting of 91.215 and the ADS-B Out of 91.225 75. Radio, Mode C transponder, ADS-B Out.

14 CFR 91.215(b) lists the airspace where an airplane must carry an operable transponder with altitude reporting:

• "In Class A, Class B, and Class C airspace areas"
• in all airspace above the ceiling and within the lateral boundaries of a Class B or Class C area up to 10,000 feet MSL
• "In all airspace of the 48 contiguous states and the District of Columbia at and above 10,000 feet MSL, excluding the airspace at and below 2,500 feet above the surface" 79.

14 CFR 91.225(d) requires ADS-B Out over nearly the same ground. It names Class B and Class C airspace areas, the 30-nautical-mile veil, the airspace above a Class B or Class C ceiling to 10,000 feet MSL, Class E at and above 10,000 feet MSL excluding the airspace at and below 2,500 feet above the surface, and Class E at and above 3,000 feet MSL over the Gulf of Mexico out to 12 nautical miles 80. The 10,000-foot item is Class E rather than all airspace, which is where the two rules differ.

The 10,000-foot requirement has an exception. High terrain can put the ground within 2,500 feet of an airplane at 11,000 feet MSL. The rule excludes that airspace, so a flight low over a 9,000-foot plateau needs no transponder from this paragraph. The exception depends on height above the ground, not on MSL altitude.

The Mode C veil is a 30-mile cylinder. The rule places it "In all airspace within 30 nautical miles of an airport listed in appendix D, section 1 of this part from the surface upward to 10,000 feet MSL" 79. The AIM repeats it and names the equipment: "aircraft operating within this airspace must be equipped with an operable radar beacon transponder with automatic altitude reporting capability and operable ADS−B Out equipment" 76. The veil has the same radius at all altitudes, so it covers the ground under each shelf and the gaps between them.

Flying beneath a Class B shelf needs no clearance. The shelf has a floor, and the airspace below that floor is not Class B. The veil still applies, because the veil is drawn from the primary airport and not from the shelves. An airplane with no transponder cannot legally fly under a Class B shelf inside 30 nautical miles of the primary airport.

Class C surrounds airports with a tower and a radar approach control. The AIM adds the third condition, "a certain number of IFR operations or passenger enplanements", and gives the usual shape: "a 5 NM radius core surface area that extends from the surface up to 4,000 feet above the airport elevation, and a 10 NM radius shelf area that extends no lower than 1,200 feet up to 4,000 feet above the airport elevation" 81. The handbook gives the same dimensions 82. The altitudes are charted in MSL even though the definition is in feet above the airport.

Entry requires established two-way radio communications. 14 CFR 91.130(c)(1) requires each person to "establish two-way radio communications with the ATC facility ... providing air traffic services prior to entering that airspace and thereafter maintain those communications while within that airspace" 83. Class D uses the same test. A controller who answers with your callsign has established communications. A controller who answers a call with aircraft calling, stand by, has not.

The Class C rule requires equipment that Class D does not. 14 CFR 91.130(d) requires the equipment of 91.215 and, after January 1, 2020, 91.225 83. The AIM lists the set: "Two-way radio; and ... an operable radar beacon transponder with automatic altitude reporting capability and operable ADS−B Out equipment" 84.

No certificate is required for Class C or Class D. The AIM states it for Class C: "No specific certification required" 84. It says the same for Class D 85. A student pilot on a solo cross-country can enter either one after establishing communications, with the instructor's general solo endorsements and no airspace-specific endorsement.

Class D surrounds an airport with an operating control tower. The AIM defines it as airspace that "extends upward from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower" 86. The handbook gives the same definition 87. Each area is tailored, and it normally contains the published instrument procedures.

The sectional shows the Class D ceiling in a dashed box. The figure reads in hundreds of feet MSL, so a box reading 27 means 2,700 feet MSL. The number is the top of the Class D, and it is an MSL number even though the airspace is defined above the airport. An airport at 200 feet with a 2,500-foot Class D carries a box reading 27.

Entry requires two-way radio communications established before the boundary. 14 CFR 91.129(c)(1) requires each person to "establish two-way radio communications with the ATC facility ... prior to entering that airspace and thereafter maintain those communications while within that airspace" 88. The pilot establishes communications before the boundary and maintains them inside. The pilot makes the call far enough out to receive the answer before the airplane reaches the boundary.

Class D requires only a radio. The AIM states the equipment: "Unless otherwise authorized by ATC, an operable two−way radio is required" 85. The Class D rule requires no transponder and no ADS-B Out. A pilot with an installed transponder still operates it, because 91.215(c) applies in all controlled airspace.

Class D exists only during the tower's hours of operation. The AIM states that a part-time Class D surface area "may revert to either a Class E surface area ... or Class G airspace", and that "The airport listing in the Chart Supplement will state the part-time surface area status (for example, 'other times CLASS E' or 'other times CLASS G')" 86. An arrival after the tower closes is an arrival into different airspace with different minimums. The Chart Supplement names the airspace that applies.

Class E is the controlled airspace that is not A, B, C or D. The AIM describes it as "controlled airspace that is designated to serve a variety of terminal or en route purposes" 89. Where nothing lower is designated, it begins at 14,500 feet MSL. Around airports and along airways it is designated much lower, and the chart shows where.

Class E stops below 18,000 feet MSL. The AIM's vertical limits paragraph gives the airspace "extending upward from 14,500 feet MSL to, but not including, 18,000 feet MSL" 89. At 18,000 feet the airspace is Class A. The AIM adds that the airspace above FL 600 is Class E again.

VFR flight in Class E requires no clearance and no certificate. The AIM states three requirements: "Pilot Certification. No specific certification required", "Arrival or Through Flight Entry Requirements. No specific requirements", and "Separation for VFR Aircraft. No separation services are provided to VFR aircraft" 90. ATC control in Class E applies to IFR traffic. 14 CFR 91.127(a) applies the Class G airport rules of 91.126 to a VFR airplane at a Class E airport 91.

A Victor airway is a Class E corridor. The AIM states that "Federal airways and low-altitude RNAV routes are Class E airspace areas and, unless otherwise specified, extend upward from 1,200 feet AGL to, but not including, 18,000 feet MSL", with VOR federal airways identified by a V prefix 92. The width taught for an airway is 4 nautical miles each side of the centerline. The Instrument Procedures Handbook gives that figure as the primary obstacle clearance area, "a protected width of 8 NM with 4 NM on each side of the centerline" 93. The area widens beyond about 51 nautical miles from the navigation aid.

Class G is uncontrolled airspace. The AIM defines it: "Class G airspace (uncontrolled) is that portion of airspace that has not been designated as Class A, Class B, Class C, Class D, or Class E airspace" 94. The handbook adds the vertical limit: "Class G airspace extends from the surface to the base of the overlying Class E airspace" 95. At most airports the layer is 700 or 1,200 feet thick. In the mountain West it can reach 14,500 feet.

ATC exercises no control over VFR traffic in Class G. The handbook states the position and its limit: "Although ATC has no authority or responsibility to control air traffic, pilots should remember there are visual flight rules (VFR) minimums that apply to Class G airspace" 95. No clearance is required and no instruction is issued. The VFR minimums, the right-of-way rules and the rest of part 91 still apply.

Self-announcing is a procedure, not a requirement for entry. The AIM describes the common traffic advisory frequency and what pilots do on it: "Pilots of inbound traffic should monitor and communicate as appropriate on the designated CTAF from 10 miles to landing. Pilots of departing aircraft should monitor/communicate on the appropriate frequency from start-up, during taxi, and until 10 miles from the airport" 96. The self-announce points are 10 miles out, entering downwind, base, final, and leaving the runway. No regulation makes the call a condition of entry, and an airplane with no radio is legal there.

14 CFR 91.117 caps indicated airspeed in three places. Paragraph (a) states that "no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.)" 97. The cap is indicated airspeed and the altitude is MSL. A Warrior never reaches 250 knots. An evaluator asks for the limit anyway, because it is part of the airspace rules.

Paragraph (b) sets a lower cap near a Class C or Class D primary airport. It applies "at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of a Class C or Class D airspace area", and the limit is 200 knots 97. The paragraph then excludes Class B: "This paragraph (b) does not apply to any operations within a Class B airspace area. Such operations shall comply with paragraph (a) of this section." Inside Class B the cap is 250 knots.

Paragraph (c) sets 200 knots under a Class B shelf. It applies "in the airspace underlying a Class B airspace area designated for an airport or in a VFR corridor designated through such a Class B airspace area" 97. The airspace inside Class B allows 250 knots, and the airspace below it allows 200 knots.

The sectional shows Class B with solid blue lines. The Chart Users' Guide gives the convention: "The MSL ceiling and floor altitudes of each sector are shown in solid blue figures with the last two zeros omitted" 98. A sector labeled 100 over 40 extends from 4,000 feet MSL to 10,000 feet MSL. Class C uses the same convention in solid magenta. Class D appears as a blue dashed line with its ceiling in a dashed blue box.

The shelf numbers are MSL. A shelf floor of 4,000 feet over ground at 3,000 feet leaves 1,000 feet of usable air. The same floor over sea level leaves 4,000 feet. The pilot does the conversion on the ground with the chart's terrain elevations. A pilot who plans to fly under a shelf computes the height of the floor above the ground along that route leg.

Class E surface areas appear as a dashed magenta line. The guide states it: "Class E Surface (SFC) Airspace is symbolized with a magenta dashed line" 99. The AIM says what such an area is for: a surface area "designated for an airport where a control tower is not in operation", extending from the surface to a designated altitude and "configured to contain all instrument procedures" 100.

The vignettes give the Class E floor. The AIM states that "Class E transition areas extend upward from either 700 feet AGL (shown as magenta vignette on sectional charts) or 1,200 feet AGL (blue vignette)" 101. It adds that both "remain in effect continuously, regardless of airport operating hours or surface area status". The Chart Users' Guide describes the same shading and gives the default: "Class E Airspace exists at 1200' AGL unless designated otherwise" 99.

Airport color on the sectional shows whether a control tower operates there. The guide states it: "Airports with Control Towers (CT) and their related data are shown in blue. All other airports and their related data are shown in magenta" 102. Blue means a tower operates there. Magenta means no tower.

14 CFR 91.155(a) sets the basic VFR weather minimums in a table. Class C, Class D, and Class E below 10,000 feet MSL carry identical values 103. That row is 3 statute miles of flight visibility, with 500 feet below, 1,000 feet above and 2,000 feet horizontal from clouds. The school calls that pattern the 3-152s. It is the row an evaluator expects first, because it covers most of the airspace a private pilot flies in.

Class B requires 3 statute miles and clear of clouds. The table gives no distances at all for Class B 103. Each airplane inside Class B holds an ATC clearance and receives separation. ATC keeps the airplanes apart, so the table sets no cloud clearance distance. The visibility stays at 3 miles.

Class G by day at or below 1,200 feet above the surface requires 1 statute mile and clear of clouds 103. The row is the lowest set of minimums in the table. It applies regardless of MSL altitude, because the measure is height above the surface.

Class G at night requires the standard set, with one exception. The same row reads 3 statute miles with 500 feet below, 1,000 feet above and 2,000 feet horizontal 103. Darkness removes the low-visibility allowance en route. An en route flight that is legal at 1 mile at sunset is not legal at 1 mile 40 minutes later. The exception is 91.155(b)(2), which allows an airplane clear of clouds in Class G below 1,200 feet above the surface "If the visibility is less than 3 statute miles but not less than 1 statute mile during night hours and you are operating in an airport traffic pattern within 1/2 mile of the runway" 104.

The Class E floor is a minimums boundary. Below the vignette the airplane is in Class G, and the Class G minimums apply. Climbing through 700 feet AGL inside a magenta vignette puts the airplane in Class E. Inside a blue vignette the boundary is 1,200 feet AGL. The 3-152s apply from that moment 103. The airplane has not moved laterally and the rule has changed.

Class G above 1,200 feet above the surface and below 10,000 feet MSL requires 1 statute mile by day 105. The cloud clearances are 500 feet below, 1,000 feet above and 2,000 feet horizontal. The visibility stays at 1 mile, which is the Class G allowance. The cloud clearances apply, because the airplane is now high enough for an IFR airplane to descend through the same air.

The same row at night requires 3 statute miles with the same three distances 105. Class G above 1,200 feet and at or above 10,000 feet MSL requires 5 statute miles. The cloud clearances are 1,000 feet below, 1,000 feet above and 1 statute mile horizontal. Class E at and above 10,000 feet MSL uses the same set.

The reason for the change at 10,000 feet is closing speed. Below 10,000 feet MSL, 14 CFR 91.117(a) caps airplanes at 250 knots. Above it there is no cap, so the larger distances give the same time at a higher speed. An applicant who names that reason answers the evaluator's follow-up question.

14 CFR 91.155(c) closes a surface area under a low ceiling. It states that "no person may operate an aircraft beneath the ceiling under VFR within the lateral boundaries of controlled airspace designated to the surface for an airport when the ceiling is less than 1,000 feet" 106. The rule applies inside the surface area of Class B, Class C, Class D, or a Class E surface area. It says nothing about a ceiling anywhere else, and there is no general VFR ceiling minimum in part 91.

14 CFR 91.155(d) sets the visibility for takeoff, landing and the pattern. No person can take off, land, or enter the traffic pattern under VFR inside such a surface area "(1) Unless ground visibility at that airport is at least 3 statute miles; or (2) If ground visibility is not reported at that airport, unless flight visibility during landing or takeoff, or while operating in the traffic pattern is at least 3 statute miles" 106. Ground visibility governs where it is reported. Flight visibility substitutes only where no ground value exists.

Both paragraphs begin with "Except as provided in § 91.157" 106. That section is Special VFR, and it is the only exception to either restriction.

The preflight use of the pair is a go or no-go test. The destination METAR gives a ceiling and a visibility, and the TAF gives them for the arrival hour. A ceiling of 900 feet at a towered airport closes it to VFR arrivals. A ground visibility of 2 miles closes it to VFR landings. The pair of numbers is 1,000 feet of ceiling and 3 statute miles of visibility. The pilot checks both before the flight, not on the approach.

Special VFR replaces the 91.155 minimums inside a surface area. 14 CFR 91.157(a) places it "below 10,000 feet MSL within the airspace contained by the upward extension of the lateral boundaries of the controlled airspace designated to the surface for an airport" 107. It is available in Class B, Class C, Class D, and Class E surface areas. It does not exist en route, and the AIM states that "ATC does not provide separation after an aircraft leaves the Class B, Class C, Class D, or Class E surface area on a special VFR clearance" 108.

The pilot asks for it. The AIM states that "A VFR pilot may request and be given a clearance to enter, leave, or operate within most Class D and Class E surface areas and some Class B and Class C surface areas in special VFR conditions, traffic permitting, and providing such flight will not delay IFR operations" 108. A controller does not offer it. The request goes to the tower where one operates, and to the nearest tower, Flight Service station, or center in a Class E surface area.

The minimums are two items. 14 CFR 91.157(b) permits special VFR only "(1) With an ATC clearance; (2) Clear of clouds; (3) Except for helicopters, when flight visibility is at least 1 statute mile" 107. One mile of flight visibility and clear of clouds. There is no cloud clearance distance at all.

Taking off or landing adds a ground visibility test. 14 CFR 91.157(c) states that no person can take off or land under special VFR "(1) Unless ground visibility is at least 1 statute mile; or (2) If ground visibility is not reported, unless flight visibility is at least 1 statute mile" 109. The pattern matches 91.155(d) with the number changed from 3 to 1.

Night special VFR requires an instrument rating. 14 CFR 91.157(b)(4) restricts it to the hours "between sunrise and sunset" unless "The person being granted the ATC clearance meets the applicable requirements for instrument flight under part 61" and "The aircraft is equipped as required in § 91.205(d)" 107. A private pilot with no instrument rating has no access to special VFR at night. Some Class B and Class C surface areas prohibit special VFR for airplanes at any hour. Part 91 appendix D section 3 lists those areas, and the sectional marks them 108.

The sectional shows special use airspace with hatched borders and a letter prefix. The Chart Users' Guide describes the chart-edge tabulation: prohibited, restricted and warning areas "are presented in blue and listed numerically", alert areas and military operations areas appear "in magenta", and "All are supplemented with altitude, time of use and the controlling agency/ contact facility, and its frequency when available" 110. The guide adds a warning for the times: "a NOTAM addressing activation will NOT be issued to announce permanently listed times of use."

A prohibited area bans flight. The AIM defines it as airspace "within which the flight of aircraft is prohibited", established "for security or other reasons associated with the national welfare" 111. Prohibited areas carry a P number, are published in the Federal Register, and are drawn on the charts.

A restricted area contains a hazard that is often invisible. The AIM names them: "unusual, often invisible, hazards to aircraft such as artillery firing, aerial gunnery, or guided missiles", and warns that "Penetration of restricted areas without authorization from the using or controlling agency may be extremely hazardous to the aircraft and its occupants" 112. Restricted areas carry an R number and are designated under 14 CFR part 73. When an area is not active and has been released to the FAA, ATC allows flight through it without a specific clearance.

A warning area is special use airspace over water. The AIM defines it as "airspace of defined dimensions, extending from three nautical miles outward from the coast of the U.S., that contains activity that may be hazardous to nonparticipating aircraft" 113. Warning areas carry a W number. The AIM adds that "A warning area may be located over domestic or international waters or both". The purpose is to warn nonparticipating pilots of the danger rather than to prohibit flight.

A military operations area separates military training from IFR traffic. The AIM gives the purpose and the activities: "air combat tactics, air intercepts, aerobatics, formation training, and low−altitude tactics" 114. A VFR flight can enter. The AIM's instruction is to "exercise extreme caution while flying within a MOA when military activity is being conducted", to contact a Flight Service station within 100 miles for the hours, and to contact the controlling agency for advisories before entering an active one.

An alert area warns of traffic volume rather than of a hazard. The AIM describes areas that "may contain a high volume of pilot training or an unusual type of aerial activity", and states the responsibility: "pilots of participating aircraft as well as pilots transiting the area must be equally responsible for collision avoidance" 115. No clearance is needed. All activity inside is conducted under the regulations without waiver.

A controlled firing area is not charted, and the AIM explains why: "its activities are suspended immediately when spotter aircraft, radar, or ground lookout positions indicate an aircraft might be approaching the area. There is no need to chart CFAs since they do not cause a nonparticipating aircraft to change its flight path" 116. The activity stops, and the airplane continues on its flight path.

Current status comes from three sources. The AIM lists them: the using or controlling agency, whose frequency is "tabulated in the margins of the applicable IFR and VFR charts", the center's airspace NOTAMs, and the FAA special use airspace website for preflight scheduling data 117. The chart margin gives the published times and altitudes. Those three sources give the activity for today.

The FAA issues a temporary flight restriction by NOTAM. 14 CFR 91.137(a) states that "The Administrator will issue a Notice to Airmen (NOTAM) designating an area within which temporary flight restrictions apply and specifying the hazard or condition requiring their imposition" 118. A TFR never appears on a printed sectional. The chart was printed before the restriction existed.

The AIM puts the duty on the pilot. It states that "Pilots are responsible to comply with 14 CFR sections 91.137, 91.138, 91.141 and 91.143 when conducting flight in an area where a temporary flight restrictions area is in effect, and should check appropriate NOTAMs during flight planning" 119. The NOTAM check at planning is therefore an airspace check. An electronic flight bag overlay helps and can lag the NOTAM.

A 91.137 restriction protects three things 118:

• persons and property on the surface or in the air, from a hazard associated with an incident on the surface
• the operation of disaster relief aircraft
• the airspace above an incident or event that can generate a high degree of public interest, against an unsafe congestion of sightseeing aircraft.

Large sporting events carry a standing security restriction of their own. The FAA issues it as a special security instruction under 14 CFR 99.7, which requires compliance with "special security instructions issued by the Administrator in the interest of national security" 120. The restriction over a major stadium event is commonly 3 nautical miles and 3,000 feet above the ground. Those figures are not in a regulation. They are in the current FDC NOTAM, and the NOTAM is what a pilot reads before the flight.

Presidential and VIP restrictions move with the person. 14 CFR 91.141 states that "No person may operate an aircraft over or in the vicinity of any area to be visited or traveled by the President, the Vice President, or other public figures contrary to the restrictions established by the Administrator and published in a Notice to Airmen (NOTAM)" 121. The area is where the person is, not where an airport is. An airplane inside one is intercepted.

The TFR check is part of the preflight action 14 CFR 91.103 requires 7. Two sources cover it: the briefing output from Flight Service or an equivalent service, and the FAA's temporary flight restriction site at tfr.faa.gov.

An air defense identification zone requires a flight plan. 14 CFR 99.11(a) states that "No person may operate an aircraft into, within, or from a departure point within an ADIZ, unless the person files, activates, and closes a flight plan with the appropriate aeronautical facility, or is otherwise authorized by air traffic control", and paragraph (c) adds that "The pilot shall designate a flight plan for VFR flight as a DVFR flight plan" 122. Filed, activated and closed. A VFR flight files DVFR.

The ADIZ also requires a radio and a transponder. 14 CFR 99.9(a) requires "a functioning two-way radio", and requires the pilot to "maintain a continuous listening watch on the appropriate aeronautical facility's frequency" 123. The same section requires the DVFR plan to carry the time and point of penetration, and requires departure within five minutes of the estimate. In the contiguous United States ADIZ, 14 CFR 99.13(c) requires the airplane to carry "a coded radar beacon transponder and automatic pressure altitude reporting equipment having altitude reporting capability that automatically replies to interrogations by transmitting pressure altitude information in 100-foot increments" 124.

Washington has a training requirement. 14 CFR 91.161(a) states that no person can serve as pilot in command or second in command "while flying within a 60-nautical mile radius of the DCA VOR/DME, under VFR, unless that pilot has completed Special Awareness Training and holds a certificate of training completion" 125. The training "is available on the FAA's Web site" and is free. The radius is 60 nautical miles, which is larger than the flight restricted zone inside it.

A special flight rules area carries its own rules in part 93. The AIM describes the family: airspace "within which the flight of aircraft is subject to the rules set forth in 14 CFR part 93, unless otherwise authorized by air traffic control", with each person required to "adhere to the special air traffic rules set forth in 14 CFR part 93, as applicable" 126. Washington and the Grand Canyon are two. The sectional shows the areas, and the pilot reads the rules before a flight goes near one.

A terminal radar service area is not an airspace class. The AIM states: "TRSAs were never controlled airspace from a regulatory standpoint ... consequently, TRSAs are not contained in 14 CFR part 71 nor are there any TRSA operating rules in 14 CFR part 91" 127. Participation is voluntary, the service is radar service, and the area is drawn "with a solid black line and altitudes for each segment". A pilot can decline it and stay legal.

The cloud clearances give a VFR pilot time to react. The handbook states the duty that goes with the airspace rules: pilots "comply with very strict FAA general operating and flight rules as outlined in the CFR, including the FAA's important 'see and avoid' mandate. These regulations provide the historical foundation of the FAA regulations governing the aviation system and the individual classes of airspace" 128. An IFR airplane can come out of a cloud at any moment. The 500, 1,000 and 2,000 feet give a VFR pilot time to see it and turn away.

Airspace risk is a position problem. A ring on a chart changes nothing until an airplane enters it and the pilot does not know the boundary is there. The handbook's method is to fix the boundaries before the flight: "The course and areas on either side of the planned route should be checked to determine if there is any type of airspace with which the pilot should be concerned or which has special operational requirements" 12. The pilot marks the boundaries against landmarks and on the moving map before takeoff.

On August 31, 1986, a Piper PA-28-181 flying VFR from Torrance to Big Bear "entered the Los Angeles Terminal Control Area (TCA) without receiving clearance from ATC as required", and collided with a DC-9 at about 6,560 feet over Cerritos, California 129. Sixty-seven people died in the two airplanes and 15 died on the ground. The report records the pilot's preparation. He asked another pilot how to stay out of the TCA, and a Los Angeles terminal area chart "was found opened in the cockpit wreckage". The Safety Board concluded "that the pilot intended to avoid the TCA but that he probably misidentified his navigational checkpoints and entered the TCA inadvertently".

The riskiest airspace is the airspace a pilot did not know was there. 14 CFR 91.103 requires familiarity with "all available information concerning that flight" 7. The pilot checks the whole route and the airspace a diversion would enter. A pilot flies a diversion at short notice to an airport off the course line. The airspace around that airport was never part of the plan.

On May 3, 2022, a private pilot took off from Calhoun County Airport in Altha, Florida, with three passengers in a Cessna 172. The airplane lifted off, stopped climbing, turned left, and struck the ground east of the runway. The pilot and one passenger died. Two passengers were seriously injured. The airplane weighed 2,424 pounds at takeoff against a maximum allowable gross weight of 2,200 pounds, and nobody computed that number 130.

The flight was a personal flight under part 91. The pilot was 56 years old. He held a private pilot certificate with a single-engine land rating and a helicopter rating, no instrument rating, and a second-class medical certificate issued in January 2021. He reported 575 hours of total flight experience on that medical application. His logbook was not found after the accident.

The airplane was a 1957 Cessna 172 with a Continental O-300-B engine rated at 145 horsepower. Its certified maximum gross weight was 2,200 pounds. It had four seats. The last annual inspection was in December 2021, and the airframe had 2,757 hours at that inspection.

The airport manager reported that the airplane departed runway 36 with full fuel tanks. The pilot sat in the left seat. The airplane owner, who held no pilot certificate, sat in the right seat. Two more passengers were on board.

Visual meteorological conditions existed at the field. The nearest reporting station, 21 nautical miles away, gave 10 miles of visibility, a clear sky, a temperature of 31 degrees Celsius, an altimeter setting of 30.00 inches of mercury, and wind from 260 degrees at 9 knots. A witness at the field said the windsock showed wind from the west at 10 to 15 knots. The runway in use was runway 36. The airport elevation is 121 feet and runway 36 is 3,729 feet of dry asphalt.

The takeoff is on video. The NTSB describes what the surveillance camera and the witnesses recorded: "the airplane took off to the north and immediately entered a nose-high attitude at slow speed while not climbing. The pilot then began a left 270° turn and crossed the departure end of the runway on an easterly heading" 130. The airplane then descended behind a hangar and hit the ground near the airport perimeter fence. A post-crash fire followed.

The engine was running the whole time. The investigation confirmed flight control continuity, found compression and valve action at all cylinders, found the carburetor inlet screen clean, and found "no evidence of a pre-existing mechanical malfunction or failure that would have precluded normal operation" 130. The flap handle was at 10 degrees and the elevator trim was neutral. Toxicology on the pilot was negative.

The weight came from the medical examiner and the hospital. The report states the method and the result: "Pilot and passenger weights were obtained from autopsy and hospital records. The airplane's weight was estimated to be 2,424 pounds, which was 224 pounds above the maximum allowable gross weight of 2,200 pounds. The center of gravity was not within the allowable operating envelope at this gross weight" 130. A surviving passenger told investigators that the pilot did not ask him how much he weighed, and that he saw no weight and balance calculation before the flight.

The NTSB determined the probable cause to be "The pilot's failure to perform a preflight weight and balance calculation and his operation of the flight at an excessive takeoff weight, resulting in an exceedance of the airplane's critical angle of attack after liftoff and an aerodynamic stall from which the pilot was unable to recover" 130.

The accident was four decisions, and each one was made on the ground. They are listed below with the Task each one belongs to and the action that would have ended the sequence safely.

One. The pilot never collected the weights. The pilot asked the passenger in the right seat to fly along and did not ask what he weighed. PA.I.F.S1 requires the applicant to "Compute the weight and balance, correct out-of-CG loading errors and determine if the weight and balance remains within limits during all phases of flight" 3. Collecting four weights takes one question each. Action: ask, write the numbers down, and run the computation.

Two. The airplane went out with full tanks and four people aboard. The airplane departed with full tanks and four people on board 130. Useful load is the maximum weight minus the basic empty weight. The crew, the passengers, the baggage and the usable fuel all come out of that one number. Avgas weighs 6 pounds per gallon. A decision to fill the tanks sets how many pounds of people the airplane can still carry. Action: compute the useful load first, subtract the people, and then decide how much fuel goes in.

Three. The pilot treated a 10 percent overload as no overload. The airplane was 224 pounds over, which the NTSB called "nearly 10% more than the maximum allowable gross weight" 130. The handbook gives the effect of 10 percent: "a 10 percent increase in takeoff gross weight would cause: • A 5 percent increase in takeoff velocity • At least a 9 percent decrease in rate of acceleration • At least a 21 percent increase in takeoff distance" 131. The higher liftoff speed and the lower climb rate are exactly what the video shows. Action: read the chart, which gives the takeoff distance and the climb rate at the actual weight.

Four. The pilot did not add the day's conditions to the load. The temperature was 31 degrees Celsius and the altimeter setting was 30.00 inches of mercury at a field 121 feet above sea level. The standard atmosphere is 15 degrees Celsius and 29.92 inches of mercury 132, so the density altitude was near 2,000 feet on a 121-foot field. The pamphlet states the principle: "if an airport whose elevation is 500 MSL has a reported density altitude of 5,000 feet, aircraft operating to and from that airport will perform as if the airport elevation were 5,000 feet", and adds that "Even at lower elevations, aircraft performance can become marginal and it may be necessary to reduce aircraft gross weight for safe operations" 133. The reported wind was 100 degrees off runway 36, so the runway component was about 1.5 knots of tailwind and about 9 knots was crosswind. Action: enter the takeoff chart at the density altitude and the actual weight, and compare the answer to the 3,729 feet available and to the climb the departure needs.

Each of the four decisions is a number that the airplane's own charts produce in a few minutes, at a table, before the engine starts. PA.I.F.R1, PA.I.F.R2 and PA.I.F.R3 are the three risk elements of Task F, and they name the use of the charts, the airplane's limitations, and the gap between calculated and actual performance 3. The Altha pilot met none of the three, and the evaluator on a checkride asks about all three.

Performance numbers come from the charts in the flight manual, entered with the actual weight, wind, temperature and altitude. The handbook describes where the numbers came from: "Information the manufacturer provides on these charts has been gathered from test flights conducted in a new aircraft, under normal operating conditions while using average piloting skills, and with the aircraft and engine in good working order" 134. The charts give runway length, fuel and time. The pilot computes all three for each flight.

The pilot interpolates conditions between the rows. The handbook gives both the method and the shortcut: "Interpolating information means that by taking the known information, a pilot can compute intermediate information. However, pilots sometimes round off values from charts to a more conservative figure. Using values that reflect slightly more adverse conditions provides a reasonable estimate of performance information and gives a slight margin of safety" 135. Round the temperature up, the altitude up and the weight up, and the chart gives a distance longer than the actual distance.

The chart's conditions are part of the data. The Warrior's takeoff chart states them in its title block: "TAKEOFF PERFORMANCE. PAVED LEVEL DRY RUNWAY. GROSS WEIGHT 2325 LBS. NO WIND. FULL POWER BEFORE BRAKE RELEASE. EXTRAPOLATION OF CHART ABOVE 7000 FT. IS INVALID", with the flap setting and the rotation speed named for each curve 136. A rolling takeoff at partial power on wet grass does not match the conditions in the title block. The number applies only under the conditions printed above it.

The 50-foot obstacle column gives a different number from the ground roll column. The handbook describes the pair: "A pilot can also compute distances for a no flap takeoff over a 50 foot obstacle scenario, as well as with flaps over a 50 foot obstacle" 137. The ground roll ends at liftoff. The obstacle column includes the air distance to 50 feet. Use that column when trees, wires or a road lie off the end of the runway.

The pilot checks the charts for each flight. Excess weight raises the takeoff speed, lengthens the takeoff run, reduces the rate and angle of climb, and lengthens the landing roll 138. Each of those numbers moves when the weight moves. A new field elevation, a new temperature, or a new passenger resets each number the charts produce.

The chart numbers came from test flights in a new airplane, flown with average piloting skills and an engine in good working order. The handbook names the limit on the data: "It is important to remember that the data from the charts will not be accurate if the aircraft is not in good working order or when operating under adverse conditions" 134. A trainer with 4,000 hours, a worn engine and a student at the controls does not match the chart conditions. The pilot adds a margin to the chart number before the flight.

An abort point is a point on the runway where the airplane must already be airborne. The Airplane Flying Handbook gives the procedure: "Prior to takeoff, the pilot should identify a point along the runway at which the airplane should be airborne. If that point is reached and the airplane is not airborne, immediate action should be taken to discontinue the takeoff. In the event a takeoff is rejected, the power is reduced to idle and maximum braking applied while maintaining directional control" 139. The pilot chooses the point before the takeoff roll starts. The pilot decides in advance what to do there, and at that point acts without deciding again.

Pressure altitude is the altimeter reading with 29.92 set. The handbook defines it as "the height above the standard datum plane", and gives three ways to find it: set 29.92 and read the indicated altitude, apply a correction factor to the indicated altitude from the reported altimeter setting, or use a flight computer 140. The pilot enters most performance charts with pressure altitude.

Density altitude is pressure altitude corrected for nonstandard temperature. The handbook defines it and then says what it means for the airplane: "Regardless of the actual altitude at which the aircraft is operating, it will perform as though it were operating at an altitude equal to the existing density altitude" 141. The worked example starts at a pressure altitude of 5,000 feet, 20 degrees above standard. The density altitude is above 7,000 feet. The 790-foot ground run becomes about 1,000 feet.

The standard atmosphere is the reference condition for both altitudes. The handbook gives it: "The standard atmosphere at sea level has a surface temperature of 59 degrees Fahrenheit (°F) or 15 degrees Celsius (°C) and a surface pressure of 29.92 inches of mercury ("Hg) or 1013.2 millibars (mb)" 132. The standard temperature lapse rate is about 2 degrees Celsius per thousand feet. The standard pressure lapse rate is about 1 inch of mercury per thousand feet up to 10,000 feet.

Any one of these conditions raises density altitude. The handbook lists the causes: "high elevations, low atmospheric pressures, high temperatures, high humidity, or some combination of these factors" 141. A hot day at a low field is enough on its own. The FAA pamphlet states the consequence for such a field: "Even at lower elevations, aircraft performance can become marginal and it may be necessary to reduce aircraft gross weight for safe operations" 133.

High density altitude reduces performance in three places at once. The wing makes less lift in thinner air, the propeller makes less thrust, and a normally aspirated engine makes less power. The pamphlet lists what a pilot sees: "Increased takeoff distance. • Reduced rate of climb. • Increased TAS (but same IAS) on approach and landing. • Increased landing roll distance" 133. The Koch chart gives an example. At 100 degrees Fahrenheit and a pressure altitude of 6,000 feet, a 1,000-foot takeoff distance becomes 3,300 feet. The 500-foot-per-minute climb becomes 120 feet per minute 142.

Only the wind components enter the performance charts. The handbook describes the tool: "The crosswind and headwind component chart allows for figuring the headwind and crosswind component for any given wind direction and velocity" 143. A 20-knot wind 60 degrees off the runway is 10 knots of headwind and 17 knots of crosswind. The headwind component enters the takeoff chart. The pilot compares the crosswind component against the demonstrated value in the flight manual.

A tailwind adds more distance than a headwind removes. The handbook gives both figures: "A headwind that is 10 percent of the takeoff airspeed reduces the takeoff distance approximately 19 percent. However, a tailwind that is 10 percent of the takeoff airspeed increases the takeoff distance approximately 21 percent" 131. The same paragraph adds that "The effect of wind on landing distance is identical to its effect on takeoff distance." A downwind departure from a short runway lengthens the ground roll and reduces the climb angle.

Published short-field performance assumes the manufacturer's technique exactly. The Airplane Flying Handbook describes it: the takeoff starts "from the very beginning of the takeoff area", the recommended flaps are extended before the roll, and the climb is held "at VX until all obstacles have been cleared, or if no obstacles are present, until reaching an altitude of at least 50 feet above the takeoff surface" 144. It also names the common error: "an attempt to pull the airplane off the ground prematurely, or to climb too steeply, may cause the airplane to settle back to the runway or make contact with obstacles." A rotation 5 miles per hour fast adds distance that no chart shows.

Flaps change both the ground roll and the climb. The Warrior's takeoff chart carries separate curves for flaps 25 degrees and flaps 0 degrees, with different rotation speeds and different distances over 50 feet 136. The general rule is that takeoff flaps shorten the ground roll and reduce the climb angle that follows, and that landing flaps steepen the approach and lower the touchdown speed. This airplane is the exception, and its manual says so in the Short Field, No Obstacle procedure: "Use of partial flaps does not decrease minimum ground roll, therefore, leave the flaps up or lower the flaps to 25° as desired" 145. Twenty-five degrees of flap in a Warrior buys the distance over a 50-foot obstacle, not the roll. The evaluator asks the general rule and then asks what your airplane's manual says, and the two answers are different here.

The runway surface is part of the calculation. The handbook states the assumption and the effect of a different surface: "Typically, performance chart information assumes paved, level, smooth, and dry runway surfaces", and "Any surface that is not hard and smooth increases the ground roll during takeoff. This is due to the inability of the tires to roll smoothly along the runway" 146. Where the flight manual gives a correction factor for grass, the pilot applies the factor. Where it gives none, the pilot adds a margin.

Slope changes the takeoff distance and the landing distance. The handbook gives the pairs: "An upsloping runway impedes acceleration and results in a longer ground run during takeoff. However, landing on an upsloping runway typically reduces the landing roll. A downsloping runway aids in acceleration on takeoff resulting in shorter takeoff distances. The opposite is true when landing" 146. An upslope lengthens the takeoff. A downslope lengthens the landing.

The airplane has two climb speeds with two different purposes. The Warrior's manual gives both: "The best rate of climb at gross weight will be obtained at 87 miles per hour. The best angle of climb is at 76 miles per hour" 147. Best rate gives the most altitude per minute. Best angle gives the most altitude per foot of ground covered. Obstacle clearance planning uses the best angle speed, because the obstacle is at a distance rather than at a time.

Climb rate falls as the airplane goes up. The handbook defines the two ceilings: "the absolute ceiling of an aircraft produces zero ROC. The service ceiling is the altitude at which the aircraft is unable to climb at a rate greater than 100 feet per minute (fpm)" 148. The service ceiling is the published number. The last thousand feet below it take a long time.

The cruise performance table links four quantities. The Warrior's range chart gives percent power against fuel flow, at 9.2, 8.0 and 6.7 gallons per hour for 75, 65 and 55 percent 23, and the true airspeed chart gives the speed for the same settings against density altitude 49. The same two pages feed the fuel plan of Task D and the true airspeed of the nav log. One power setting fixes the fuel flow, the true airspeed, the time and the fuel required.

Ground effect reduces induced drag within about a wingspan of the surface. The handbook gives the numbers: a reduction of 1.4 percent at a height equal to the span, 23.5 percent at a quarter of the span, and 47.6 percent at a tenth of the span 149. It then names the condition: "In extreme conditions, such as high gross weight, high density altitude, and high temperature, a deficiency of airspeed during takeoff may permit the aircraft to become airborne but be incapable of sustaining flight out of ground effect. In this case, the aircraft may become airborne initially with a deficiency of speed and then settle back to the runway." That paragraph describes the Altha takeoff. The handbook was printed years before the accident.

Stall speed rises with the square root of load factor. The handbook gives the bank angles and the arithmetic: "The load factor for any aircraft in a coordinated level turn at 60° bank is 2 Gs. The load factor in an 80° bank is 5.76 Gs" 150. The same chapter states that stalling speed increases in proportion to the square root of the load factor, and gives the example: "an aircraft with a normal unaccelerated stalling speed of 50 knots can be stalled at 100 knots by inducing a load factor of 4 Gs" 150. Two g raises the stall speed by about 41 percent.

Stall speed also rises with weight, and each table is keyed to a weight. The Warrior's manual states its own: "Stall speed at a gross weight of 2325 pounds with power off and full flaps is 58 miles per hour. With flaps up, this speed is increased. The stall speed chart is at gross weight. Stall speeds at lower weights will be correspondingly less" 147. Above gross weight the stall speed is higher than the chart shows, and the chart no longer applies.

A forward center of gravity is stable and nose-heavy. The handbook describes the effect: "Loading in a nose-heavy condition causes problems in controlling and raising the nose, especially during takeoff and landing", and exceeding the forward limit "may result in excessive loads on the nosewheel, a tendency to nose over on tailwheel type airplanes, decreased performance, higher stalling speeds, and higher control forces" 151. The flare takes more force.

An aft center of gravity is less stable. The handbook states the effect: "Loading in a tail heavy condition has a serious effect upon longitudinal stability, and reduces the capability to recover from stalls and spins. Tail heavy loading also produces very light control forces, another undesirable characteristic. This makes it easy for the pilot to inadvertently overstress an aircraft" 151. As the center of gravity moves aft, the airplane returns to level flight more slowly after a maneuver or a gust.

Aft of the approved limit, spin recovery can become impossible. The Warrior's manual says so directly: "If the C.G. is too far aft, the airplane may rotate prematurely on takeoff or try to pitch up during climb. Longitudinal stability will be reduced. This can lead to inadvertent stalls and even spins; and spin recovery becomes more difficult as the center of gravity moves aft of the approved limit" 152. The same section states a loading limit: "you cannot fill the airplane with the maximum number of adult passengers, full fuel tanks and maximum baggage."

Weight times arm equals moment. The handbook gives the sequence: "Enter the moment for each item listed. Remember 'weight x arm = moment.' 3. Find the total weight and total moment. 4. To determine the CG, divide the total moment by the total weight" 153. Moments are expressed in pound-inches. The center of gravity comes out in inches from the datum.

The datum is a line the manufacturer draws. The handbook defines it as "an imaginary vertical plane or line from which all measurements of arm are taken. The datum is established by the manufacturer" 154. An arm measured aft of the datum is positive and an arm measured forward of it is negative. Each station in the airplane is measured from that one line. Two airplanes with different datums give different arms for the same seat.

Fuel and oil have standard weights. The handbook lists gasoline at 6 pounds per US gallon and oil at 7.5 pounds per US gallon, with a caution: "These weights should not be used if actual weights are available" 154. Forty-eight usable gallons of avgas is 288 pounds. That figure is part of the useful load, and it changes with the amount of fuel loaded.

Moving weight changes the center of gravity in proportion. The handbook describes the direction and the proportion: "When weight is moved forward, the total moments decrease; when weight is moved aft, total moments increase. The moment change is proportional to the amount of weight moved" 155. The formula follows from that proportion: weight moved times distance moved equals total weight times the change in center of gravity. The formula gives the change in inches when a bag moves from the baggage bay to the back seat.

Basic empty weight is more than the airframe. The handbook defines standard empty weight as the weight of "the airframe, engines, and all items of operating equipment that have fixed locations and are permanently installed in the aircraft, including fixed ballast, hydraulic fluid, unusable fuel, and full engine oil", and defines basic empty weight as that figure "plus the weight of optional and special equipment that have been installed" 154. The Warrior's manual uses the same convention: "Basic weight consists of the empty weight of the aircraft plus the unusable fuel and full oil capacity" 152. Confirm what the figure includes before subtracting it.

The airplane's own weighing record is the legal source. The Warrior's revision sheet carries the numbers for one airframe: "CURRENT EMPTY AIRPLANE 1436.7, 86.6, 124430.8. USEFUL LOAD 2325-1437 = 888" 156. An avionics change moved that airplane's empty weight by 5.4 pounds and its arm by 0.2 inches. The manual's own instruction is that "The current values should always be used", and that a mechanic who adds equipment computes a new basic weight and writes it in the logbook 152. The sample problem printed in the book gives the numbers for no actual airplane.

Useful load is what is left. The handbook defines it as "the weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil. It is the basic empty weight subtracted from the maximum allowable gross weight" 154. One number covers the people, the bags and the fuel. Full tanks account for part of that number before anybody boards.

The envelope chart shows whether the loaded airplane is within limits. The Warrior's chart plots weight in pounds against the center of gravity in inches from the datum, with a solid line for the normal category and a dashed line for the utility category 157. The normal category line runs from 83.0 inches at 1,950 pounds up to 87.0 inches at 2,325 pounds, flat across to 93.0 inches, and back down the 93.0-inch line. The loaded point must fall inside the line. A point outside the line means the airplane must not fly, whatever the arithmetic looked like.

Fuel burn moves both the weight and the center of gravity. The handbook gives the general rule and the usual case: "Fuel burn can also affect the CG based on the location of the fuel tanks. For example, most small aircraft carry fuel in the wings very near the CG and burning off fuel has little effect on the loaded CG" 151. Little is not none, and the weight always falls. PA.I.F.S1 asks the applicant to "determine if the weight and balance remains within limits during all phases of flight" 3, so the pilot plots both the takeoff point and the landing point.

An overloaded airplane performs worse in eleven ways. The handbook lists them 138:

• higher takeoff speed
• longer takeoff run
• reduced rate and angle of climb
• lower maximum altitude
• shorter range
• reduced cruising speed
• reduced maneuverability
• higher stalling speed
• higher approach and landing speed
• longer landing roll
• excessive weight on the nose wheel or tail wheel. The structural margin falls as well, because the limit load factor is defined at the certificated weight. Above gross weight the performance charts stop describing the airplane.

The baggage placard is a structural limit. The Warrior carries one on the inside of the baggage compartment door: "BAGGAGE MAXIMUM 200 LBS", beside a placard restricting utility category operation to no baggage and no aft passengers 158. The floor and the tie-downs are certified to the placarded weight. A bag inside the weight and balance envelope can still exceed the placard, and the placard is the binding limit.

Operating limitations bind wherever they are written. 14 CFR 91.9(a) states that "no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual, markings, and placards" 159. Three places carry the same legal force: the flight manual, the instrument markings, and the placards. An airspeed limit marked on the dial is binding under 91.9(a).

The airspeed limits appear on the dial and in the manual. The Warrior's flight manual gives them: "NEVER EXCEED 176 MPH. MAXIMUM STRUCTURAL CRUISE 140 MPH. MANEUVERING 124 MPH. ... FLAPS EXTENDED (Ser. nos. 7615001 and up) 115 MPH" 160. The red radial line is the never-exceed speed. The top of the green arc is the maximum structural cruising speed, and the yellow arc above it is for smooth air only. The top of the white arc is the maximum flaps-extended speed. Maneuvering speed appears on no arc, so the pilot reads it from the manual or the placard.

Runway selection is a computed decision made before taxi. One NTSB report describes a takeoff planned without performance calculations. An airline transport pilot with 9,429 hours and 22 hours in a Cherokee 140 took off from Panguitch, Utah. The takeoff was at 7 in the evening in August with three people aboard. He "calculated the airplane's weight with passengers and fuel, and determined it to be about 20 pounds under the maximum gross weight", and "did not conduct preflight performance calculations prior to takeoff" 161.

The chart did not cover the day's density altitude. The report notes that the manual's takeoff distance chart "states 'extrapolation of chart above 7,000 ft. [density altitude] is invalid", and that "The calculated density altitude at the time of the accident was 9,000 ft mean sea level" 161. The airplane climbed to about 100 feet, began descending, and landed in the terrain ahead. The pilot told investigators "that if he took more time in preflight preparations, he would have noticed that the density altitude was too high to takeoff". Nobody was hurt.

Four inputs go into the runway decision:

• performance and limitations for this airplane at this weight
• the distance available
• the surface
• the wind.

The pilot weighs each input against what he can fly today. A weight within limits is a different question from a density altitude within the chart. A weight 20 pounds under the limit gives no information about a density altitude beyond the chart's last row.

The go-around is part of the same decision. Density altitude affects the flight after liftoff as well. A go-around at a high-density-altitude field climbs at the same reduced rate the takeoff did, and the Koch chart's example turns a 500-foot-per-minute climb into 120 feet per minute 142. The obstacles on the go-around path are therefore part of the runway choice, made at the table with the chart.