PART 61KSNSGROUND SCHOOL
North Aero NORTH AERO

Phase 1 · Module 1-11

Communications and Light Gun Signals

The FAA publishes each frequency a pilot needs. The sectional chart and the Chart Supplement list the frequencies for an airport:

The AIM says the CTAF "is contained in the Chart Supplement U.S., Chart Supplement Alaska, Alaska Terminal Publication, Instrument Approach Procedure Charts, and Instrument Departure Procedure (DP) Charts" . A pilot reads the frequency from one of these sources and does not guess it.

What the CTAF is

The Common Traffic Advisory Frequency is one frequency per airport. Pilots use it for advisories when no tower is operating. The AIM: "The CTAF may be a UNICOM, MULTICOM, FSS, or tower frequency and is identified in appropriate aeronautical publications" . At an airport with a part-time tower, the tower frequency is the CTAF when the tower is closed. At an airport with no tower, the CTAF is the UNICOM frequency, or MULTICOM where there is no UNICOM. The Chart Supplement entry for the school's airport names its CTAF.

The self-announce call

A self-announce call has four parts, and the airport name opens and closes it. AC 90-66C defines the procedure: "pilots broadcast their aircraft call sign, position, altitude, and intended flight activity or ground operation on the designated CTAF." The call names the airplane type, not its color, and uses the runway number, not "active runway," and "the airport name should be spoken at the beginning and end of each self-announce transmission" . The parts are:

The position reports have the same form on each leg of the pattern. AC 90-66C gives them: "Entering left/right downwind for runway [XX];" "On the left/right downwind for runway [XX];" "On left/right base for runway [XX];" "On final for runway [XX]" . The last call reports the airplane clear of the runway. The AIM's table sets the inbound call at 10 miles out and the outbound calls before taxiing and before taxiing onto the runway .

What not to say

"Any traffic in the area, please advise" is not a call. AC 90-66C: "Pilots are reminded that the use of the phrase 'ANY TRAFFIC IN THE AREA, PLEASE ADVISE' is not a recognized self-announce position and/or intention phrase and should not be used under any condition. Any traffic that is present at the time of your self-announcement that is capable of radio communications should reply without being prompted to do so" . The phrase adds a transmission and carries no information. The AIM's standard for the frequency is one sentence: "Jargon, chatter, and 'CB' slang have no place in ATC communications" .

The first call to any controller has a fixed form. The AIM's format for initial contact is :

The AIM adds that including "your request, your position or altitude, and the phrase '(ATIS) Information Charlie received' in the initial contact helps decrease radio frequency congestion." AC 91-73B says the same for ground and tower: "state who you are (make and registration number), where you are on the airport, what you want, and what you know," with the example "Cessna N1234, at SeaBreeze FBO, VFR to taxi, with information Alpha" .

Phonetics and figures

A pilot speaks letters in the ICAO phonetic alphabet. The AIM: "Pilots should use the phonetic alphabet when identifying their aircraft during initial contact with air traffic control facilities," and controllers "may also request pilots to use phonetic letter equivalents when aircraft with similar sounding identifications are receiving communications on the same frequency" . A pilot speaks each digit of a number other than a round hundred or thousand: "All other numbers must be transmitted by pronouncing each digit," and a frequency's decimal point "is spoken as 'POINT'" . A frequency is "one one nine point five two five." A heading is "two seven zero." A misheard call sign or heading can start a runway incursion, and speaking each digit reduces that risk.

The standard responses

Five responses have fixed meanings in the Pilot/Controller Glossary :

STAND BY is never the answer to a hold-short instruction. The pilot reads back a hold-short instruction with the runway number and the call sign, or says UNABLE. The AIM's rule for each exchange: "It is essential, therefore, that pilots acknowledge each radio communication with ATC by using the appropriate aircraft call sign" .

A pilot always reads back three kinds of instruction in full. The AIM: "When taxi instructions are received from the controller, pilots should always read back: (a) The runway assignment. (b) Any clearance to enter a specific runway. (c) Any instruction to hold short of a specific runway or line up and wait" . AC 91-73B adds the takeoff and landing clearances and the form: "Ensure that you include the complete call sign and runway designator when reading back a clearance to enter a specific runway, hold short of a runway, or taxi to LUAW. Avoid using 'Roger' or 'Wilco' in these instances" . The readback is the controller's check that the right airplane received the instruction.

The AIM says the tower "will not use the word 'cleared' in conjunction with authorization for aircraft to taxi." A taxi instruction is an instruction. ATC reserves "Cleared" for the runway .

Line up and wait

"Line up and wait" puts the airplane on the runway and nothing more. The AIM: the instruction "is used to instruct a pilot to taxi onto the assigned departure runway, align the aircraft with the correct departure direction and await for further ATC instructions. LUAW is not an authorization to takeoff." The AIM's note records that "a significant number of pilots read back LUAW instructions correctly and departed without a takeoff clearance." The AIM also says: "If a takeoff clearance is not received within a reasonable amount of time after instructed to LUAW, ATC should be contacted" . AC 91-73B gives flight schools a number: after 90 seconds with no takeoff clearance, the pilot asks and watches the tower for a light . On the runway the pilot listens to the frequency and watches final.

The clearance is not a command to break a rule

An ATC clearance authorizes. The AIM defines it as "an authorization by ATC, for the purpose of preventing collision between known aircraft, for an aircraft to proceed under specified conditions within controlled airspace. IT IS NOT AUTHORIZATION FOR A PILOT TO DEVIATE FROM ANY RULE, REGULATION, OR MINIMUM ALTITUDE NOR TO CONDUCT UNSAFE OPERATION OF THE AIRCRAFT." When a clearance would require a deviation or an unsafe operation, "IT IS THE PILOT'S RESPONSIBILITY TO REQUEST AN AMENDED CLEARANCE." A pilot who prefers a different runway or a delay "IS EXPECTED TO INFORM ATC ACCORDINGLY" . The word is UNABLE.

Section 91.123 binds the pilot to an accepted clearance: "no pilot in command may deviate from that clearance unless an amended clearance is obtained, an emergency exists, or the deviation is in response to a traffic alert and collision avoidance system resolution advisory." The same section says "when a pilot is uncertain of an ATC clearance, that pilot shall immediately request clarification from ATC" .

The late runway change

A runway change on downwind or on final can cause a rushed configuration and a wrong-runway lineup. The pilot briefed one runway. The new runway has its own:

AC 91-73B writes its rule for a late turnoff instruction: "do not accept last-minute ATC turnoff instructions unless you clearly understand the instructions and are certain that you can safely comply" . The module applies the same rule to a late runway change. The defense has four steps:

A go-around and a second pattern cost two minutes.

The flight of N1285U

On August 16, 2015, at 11:03 in the morning, a Cessna 172 and a Sabreliner business jet collided at Brown Field, San Diego. The collision was on the right downwind for runway 26R, about a mile northeast of the airport. The Cessna's pilot was a 60-year-old private pilot with 277 hours, 9.7 of them in the last six months. He flew alone and practiced touch-and-goes. The Sabreliner, call sign Eagle1, was inbound from a Navy contract flight with two pilots and two mission specialists. All five died .

Brown Field has a tower and two parallel runways. The pattern for both was right traffic that morning. The tower had combined its two positions at one seat. A trainee controller worked there under a qualified controller. The Cessna's pilot called in at 10:49 for touch-and-goes. Over the next ten minutes the traffic grew until the report says the controller "was controlling nine aircraft." Among them were:

The trainee cleared the Cessna for a touch-and-go on 26R. The pilot went around, and the trainee told him to expect 26L on the next approach. He landed on 26L. He turned right across the departure path of 26R and entered a right downwind for 26R. Three minutes before the collision the qualified controller took the frequency back.

In the next two minutes the controller:

The Sabreliner's cockpit voice recorder recorded its pilot saying "wowww, he's like panicking." The Sabreliner reported midfield downwind with traffic in sight left and right. The airplane on its right, between it and the tower, 500 feet below, was the accident Cessna.

The controller thought the airplane on the Sabreliner's right was the other Cessna, N6ZP. He had already cleared N6ZP to leave, and it was two miles away, outbound. He told N6ZP to make a right 360 and rejoin the downwind. N6ZP's pilot read it back and began the turn, two miles from the airport. The accident Cessna had heard nothing addressed to it for almost six minutes. It continued along the downwind.

Ten seconds later the controller turned the Sabreliner onto base and cleared it to land. He looked up and saw the Cessna on downwind, still not turning. He called N6ZP again. N6ZP's pilot said he was in the turn. The Sabreliner's pilot said "I see the shadow but I don't see him."

At 11:03:04 the controller transmitted "November eight five uniform," the first call to the accident airplane in six minutes. Its pilot answered "eight five uniform." The controller asked whether he was still on the right downwind. The pilot did not answer. The two airplanes collided as the controller and the trainee watched.

The probable cause was the controller's "failure to properly identify the aircraft in the pattern and to ensure control instructions provided to the intended Cessna on downwind were being performed before turning Eagle1 into its path for landing." Contributing were his incomplete picture of the traffic after taking over, and "the inherent limitations of the see-and-avoid concept" .

Where a pilot could have prevented the accident

The accident started in the tower. Each decision below is listed with the PAVE category that applied to it and the call or action that would have prevented the collision.

E

Nine aircraft on one frequency, two runways, a trainee handing off to a controller mid-pattern. The controller told the NTSB his personal limit was seven.

The safe decision: listen to each call on the frequency and place each airplane. A frequency this busy, with corrected instructions and a wrong-runway clearance in two minutes, is itself information. The AIM asks pilots "to maintain vigilance in monitoring air traffic control radio communications frequencies for potential traffic conflicts with their aircraft."

P

The controller told N6ZP to make a right 360 and rejoin the downwind. N6ZP was two miles out, cleared to leave, and turned anyway.

The safe decision: an instruction that does not fit your airplane requires a question before compliance. A pilot cleared to depart who is told to rejoin the downwind says so: "N6ZP is departing to the northeast, confirm the 360 is for us." Section 91.123 says a pilot uncertain of a clearance "shall immediately request clarification." The NTSB wrote that the pilot "might have reminded the controller that he was departing the airspace or requested clarification."

P

The Cessna on downwind heard a jet report traffic in sight left and right, and heard a Cessna told to turn 360 over the airport. It heard nothing with its own call sign.

The safe decision: when no call on the frequency has included you, say where you are. "Brown Tower, Cessna one two eight five uniform, right downwind two six right, abeam the tower." One call would have told the controller which Cessna was where and told the Sabreliner what was below it. Six minutes of silence is not a clearance to keep flying.

A

The controller turned the Sabreliner onto base with the Cessna below and inside it. He then spent fourteen seconds verifying call signs. The NTSB wrote that his priority should have been a safety alert to the Sabreliner.

The safe decision: a controller can be wrong, and the see-and-avoid duty stays with the pilot. The Sabreliner's crew had "the guy on the right side" in sight half a minute earlier and then lost him against the ground. A pilot who loses sight of known traffic before a turn toward it says so. The pilot does not turn until the traffic is back in sight.

✕

11:03: "November eight five uniform." "Eight five uniform." "Are you still on the right downwind?" No answer. Five dead.

The first transmission between the controller and the Cessna came seconds before the collision, and it was a call sign. The Cessna's pilot answered it correctly.

A tower that cannot reach an airplane by radio uses a light. The AIM: the light gun procedures "are used by ATCTs in the control of aircraft, ground vehicles, equipment, and personnel not equipped with radio," and "to control aircraft, ground vehicles, equipment, and personnel equipped with radio if radio contact cannot be established." The light can only approve or disapprove the pilot's current action, and "pilots may not be looking at the control tower at the time a signal is directed toward their aircraft" . The table at 91.125 gives the meanings . Each signal has one meaning on the surface and one in flight.

Green

Steady green on the ground is "cleared for takeoff." Steady green in flight is "cleared to land." Flashing green on the ground is "cleared to taxi." Flashing green in flight is "return for landing (to be followed by steady green at proper time)" . A flashing green in flight is not a landing clearance. The pilot returns to the pattern and waits for the steady green.

Red

Steady red on the ground is "stop." Steady red in flight is "give way to other aircraft and continue circling." Flashing red on the ground is "taxi clear of runway in use." Flashing red in flight is "airport unsafe—do not land" . Steady red means keep circling. Flashing red means the airport is unsafe and the pilot must not land.

Flashing white has one meaning, on the surface only: "return to starting point on airport." In flight it is "not applicable" . Alternating red and green means "exercise extreme caution" on the surface and in flight . The AIM calls it the "General Warning Signal," and it "advises the pilot to be on the alert" . The alternating signal is the only one that carries information beyond approval or disapproval.

Getting the tower's attention, and answering

The pilot has no radio to answer with, so the pilot answers with the controls or the lights. The AIM: "During daylight hours, acknowledge tower transmissions or light signals by moving the ailerons or rudder. At night, acknowledge by blinking the landing or navigation lights." In flight by day, the pilot rocks the wings. To get the tower's attention at night, "turn on a landing light and taxi the aircraft into a position, clear of the active runway, so that light is visible to the tower" . A pilot whose radio fails after leaving the ramp watches the tower for lights. A pilot whose radio fails in flight squawks 7600 and flies the pattern while watching the tower.

The transponder answers radar with a code and an altitude. The VFR code is 1200. The AIM: "Unless otherwise instructed by an ATC facility, adjust transponder/ADS-B to reply on Mode 3/A Code 1200 regardless of altitude," and "pilots must always operate that equipment with altitude reporting enabled unless otherwise instructed by ATC" . The regulation requires the transponder on, with Mode C if installed, in all controlled airspace and in the airspace where one is required, replying "on the appropriate code or as assigned by ATC" . The AIM asks for altitude reporting "any time the aircraft is positioned on any portion of the airport movement area" . In the Warrior the pilot sets the switch to ALT before the airplane moves and leaves it there until the airplane is parked.

The emergency codes

Three codes are reserved:

For a lost radio, "the pilot should adjust the transponder to reply on Mode A/3, Code 7600" . For distress or urgency, the pilot "should squawk Mode 3/A, Code 7700/Emergency and Mode C altitude reporting and then immediately establish communications with the ATC facility." Code 7700 "normally triggers an alarm or special indicator at all control positions" .

Changing codes

A code change passes through other codes. The AIM: "When making routine code changes, pilots should avoid inadvertent selection of Codes 7500, 7600 or 7700 thereby causing momentary false alarms at automated ground facilities. For example, when switching from Code 2700 to Code 7200, switch first to 2200 then to 7200, NOT to 7700 and then 7200" . A momentary 7700 causes a false alarm at a ground facility.

VFR flight following is radar traffic information that ATC gives a VFR airplane on request. The AIM: "Pilots receiving this service are advised 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. This service is not intended to relieve the pilot of the responsibility for continual vigilance to see and avoid other aircraft." ATC gives it at the controller's discretion: "controller workload and communications frequency congestion, could prevent the controller from providing this service." ATC gives it to VFR flights "when requested by pilots of such flights" . The request is one transmission to approach or center:

What radar adds

A controller who has the airplane on radar can also warn the pilot. The AIM: "A safety alert will be issued to pilots of aircraft being controlled by ATC if the controller is aware the aircraft is at an altitude which, in the controller's judgment, places the aircraft in unsafe proximity to terrain, obstructions or other aircraft," and "once the alert is issued, it is solely the pilot's prerogative to determine what course of action, if any, to take" . A pilot can request vectors. The pilot requests flight following on each flight that leaves the pattern, because the help costs one call.

MAYDAY and PAN-PAN

A pilot in trouble "can obtain assistance simply by contacting the air traffic facility or other agency in whose area of responsibility the aircraft is operating, stating the nature of the difficulty, pilot's intentions and assistance desired." The formal signals come first in the call: "any subsequent transmissions by an aircraft in distress should begin with the signal MAYDAY, preferably repeated three times. The signal PAN-PAN should be used in the same manner for an urgency condition." Distress "commands radio silence on the frequency in use" . Plain words are also enough: "Warrior two two one delta is declaring an emergency." The AIM's message elements, in order, are :

The pilot gives as many as needed.

What it costs

Declaring an emergency costs nothing by rule. Section 91.3(b) lets the pilot in command "deviate from any rule of this part to the extent required to meet that emergency," and 91.3(c) says the pilot "shall, upon the request of the Administrator, send a written report of that deviation" . The pilot sends the report only if the Administrator asks for it. The hazard is delay. A pilot who waits to declare until the trouble is certain loses the time that an earlier declaration would have provided. The AIM asks the pilot in distress to "comply with advice and instructions received," and adds, "Do not hesitate to ask questions or clarify instructions when you do not understand or if you cannot comply" .

Runway status lights are red lights in the pavement that come on automatically. The AIM: "RWSL is a fully automated system that provides runway status information to pilots and surface vehicle operators to clearly indicate when it is unsafe to enter, cross, takeoff from, or land on a runway." The lights come on when "there is high speed traffic on the runway or there is an aircraft on final approach within the activation area." They are "an independent safety enhancement that does not substitute for or convey an ATC clearance" . Red means stop, with or without a clearance. When a clearance and the lights conflict, the pilot holds and asks.

The call that was not yours

Blocked and garbled calls are normal on a busy frequency. When two airplanes transmit at once, both transmissions are lost. A clearance heard through a block is not a clearance. AC 91-73B: "Be especially vigilant if another aircraft that has a similar call sign is on frequency. Care should be taken to avoid inadvertently executing a clearance or instruction for another aircraft," and "Pilots should not perform any nonessential tasks while communicating with ATC" .

The pilot acts only on a clearance heard whole, with the pilot's own call sign in it. The pilot reads it back with the call sign so that the controller can catch a mismatch. At Brown Field the controller's instruction went to the wrong Cessna, and the pilot of that Cessna read it back and flew it. AC 91-73B's flight-school rule covers final: a pilot who has not heard a landing clearance asks, "am I cleared to land?", and with no answer goes around .

Sources for this module

You are not asked to read these end to end. Have them, and know where in them this module lives. On the checkride you may open the handbook and you may not open this site. Each one links to where you get it. Reading a full chapter is worth it, and it is not required to pass this module.

Your study guide and quiz

The facts to remember are:

Study guide — Module 1-11 (PDF)

Write the quiz answers in full. On the checkride the examiner shows a flashing green light and asks what it means in flight. The answer is return for landing, and the steady green comes later.