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Private pilot · ACS PA.III.A · lesson pack

Communications, Light Signals, and Runway Lighting Systems

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Why this one matters

Runway incursions and near collisions often start with a misunderstood or unchecked radio call: a hold-short instruction heard as a clearance, a call sign confused with another, a frequency nobody was listening on. Clear, standard phraseology and a known plan for when the radio fails keep everyone sharing the same picture of the airport.

1 · Know these cold

  • •Find frequencies in the Chart Supplement, on the sectional and from ATIS; set them up before you need them.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique))
  • •Who you’re calling, who you are, where you are, what you want. Listen before you talk, and read back runway assignments and every hold-short instruction.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique))
  • •Light signals: steady green, cleared to land (in the air) or take off (on the ground); flashing green, return for landing (to be followed by a steady green at the proper time; it isn't a landing clearance) or cleared to taxi; steady red, give way and keep circling or stop; flashing red, airport unsafe or taxi clear of the runway; flashing white, return to your starting point (ground); alternating red and green, extreme caution.(14 CFR 91.125)
  • •Lost communications in VFR conditions: squawk 7600, stay VFR and land as soon as practicable. At a towered airport, watch for light signals and acknowledge them.(AIM 4-2-13 and 6-4-1; 14 CFR 91.129(d)(2))
  • •Red runway status lights mean stop: don't enter, cross or take off while they're on, and call the tower. They are an independent advisory system: they never give, replace or cancel a clearance, and their going out is not a clearance.(AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids)
  • •Declare an emergency early: "Mayday" for distress, "Pan-pan" for urgency, and squawk 7700.(AIM, Chapter 6, Emergency Procedures)
  • •Accidents and certain serious incidents must be reported to the NTSB immediately; a written report follows within 10 days of an accident.(49 CFR 830.5; 830.15)

2 · The lesson

Frequencies and phraseology
  • Frequencies come from the Chart Supplement, the sectional chart (tower, CTAF, ATIS, approach) and the ATIS broadcast. Load and label them before you need them.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique))
  • Listen before transmitting so you don’t step on someone. Think about what you’ll say, then say it briefly: facility, your call sign, position, request. At a towered airport, read back runway assignments, hold-short and LAHSO instructions, taxi routes, altitudes and headings, with your call sign.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique))
  • At a nontowered airport: self-announce on the CTAF with the airport name, your call sign, position and intentions, on each leg of the pattern and on the ground, and listen for everyone else.(AIM 4-1-9; AC 90-66)
  • Use the standard words from the Pilot/Controller Glossary: "unable", "say again", "wilco", "roger". Non-standard phrases are how misunderstandings start.(Pilot/Controller Glossary (AIM))
  • Read back runway assignments, hold-short instructions, altitudes and headings. If you’re unsure, ask; never guess.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique))
  • Student pilots may say so on first contact, and controllers will adjust. That’s good airmanship, not a weakness.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique))
Transponder and radar help
  • An altitude-reporting transponder is required in the airspace listed in 91.215(b), and in all controlled airspace it must be on (your assigned code, or 1200 for VFR) unless ATC says otherwise; in uncontrolled airspace the AIM asks you to operate it whenever practicable. Press IDENT only when ATC asks.(14 CFR 91.215(b)-(c); AIM 4-1-20)
  • Special codes: 7500 hijacking, 7600 lost communications, 7700 emergency.(AIM, Chapter 4 (air traffic control: services, airport operations))
  • Radar services for VFR pilots include traffic advisories (flight following), safety alerts and help when lost. Ask for it; it doesn’t replace see-and-avoid.(AIM, Chapter 4 (air traffic control: services, airport operations))
When the radio quits
  • Check the simple things first: volume, squelch, the right frequency, the audio panel selection, headset plugs, a stuck mic, the avionics master. A failing alternator can drain the battery and take the radios with it.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique))
  • In VFR conditions with no radio, squawk 7600, stay VFR, and land as soon as practicable. In Class D, stay clear until you know the traffic flow, then join it; you may land without two-way radio only with the weather at or above basic VFR minimums, visual contact with the tower maintained, and a clearance to land by light gun (a steady green).(AIM 4-2-13 and 6-4-1; 14 CFR 91.129(d)(2))
  • Don't confuse this with 91.185: that is the IFR lost-communications rule (route and altitude to fly when you lose the radio on an IFR flight plan).(14 CFR 91.185)
  • Know which part failed. Transmitter dead, receiver working: listen, comply, and acknowledge by rocking the wings (day) or blinking lights (night). Receiver dead, transmitter working: transmit your position, altitude and intentions in the blind, say you'll be controlled by light signals, report joining the pattern, and watch the tower. Both dead: squawk 7600, stay clear until you know the flow, join it, and rely entirely on light signals.(AIM 4-2-13)
  • Acknowledging light signals: in flight, rock the wings by day, blink the landing or navigation lights at night; on the ground, move the ailerons or rudder by day, blink the landing or navigation lights at night.(AIM 4-3-13)
  • Know the light gun signals cold: the meaning is different in the air and on the ground.(14 CFR 91.125)
Airport and runway lighting
  • Runway Status Lights work automatically from surveillance data, independently of ATC: red Runway Entrance Lights at a taxiway mean don’t enter or cross; red Takeoff Hold Lights on the runway mean don’t take off; Runway Intersection Lights mean don't enter or cross an intersecting runway. Stop and contact the tower. They never give, replace or cancel a clearance, and lights going out isn't a clearance. If they come on when you're already on the runway or can't safely stop, use your best judgment and call ATC at the first chance.(AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids)
  • PAPI (four lights): 4 white high, 3 white and 1 red slightly high, 2 and 2 on the glidepath, 1 white and 3 red slightly low, 4 red low; a two-light PAPI shows 1 white and 1 red on path. VASI: red over white on the glidepath, white over white high, red over red low.(AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids)
  • Runway lights: edge lights white, turning yellow for the last 2,000 feet or half the runway, whichever is less; threshold lights green from the approach end; runway end lights red; REIL, flashing white lights at the threshold. Taxiway edge lights are blue and centerline lights green.(AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids)
  • The rotating beacon flashes white and green at a lighted land airport, white and yellow at a water airport, green, yellow and white at a heliport, and two quick white flashes between greens at a military airport. In daylight, a beacon on in a Class B, C, D or E surface area often means the ceiling is below 1,000 feet or visibility below 3 miles, but nothing requires it, so check the actual weather.(AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids)
  • Pilot-controlled lighting, on the frequency in the Chart Supplement: key the mic 7 times in 5 seconds for the highest intensity available, 5 for medium or lower (or to turn the REIL lower or off), 3 for the lowest; what you get depends on the installed system. Always key 7 first, then step down. The lights stay on for 15 minutes from the last activation.(AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids)
Emergencies and reporting
  • Declare an emergency when you are in distress or urgency, or when you think you might be. You get priority; there is no penalty for asking for help you needed.(AIM, Chapter 6, Emergency Procedures)
  • An accident involves death, serious injury or substantial damage. Notify the NTSB immediately after an accident, and after listed serious incidents such as a flight control failure, an in-flight fire or a midair collision.(49 CFR 830.2; 830.5)
  • File the written report within 10 days of an accident, or 7 days after an aircraft is still missing. For incidents, only if the NTSB asks.(49 CFR 830.15)

Want it all on one page, with scenarios? Read the full lesson.

3 · Say it out loud

Answer each one out loud, then check yourself and mark how it went.

  1. Remember Recall it

    “What does a flashing green light from the tower mean on the ground, and in the air?”

  2. Understand Explain why

    “Why must you read back a hold-short instruction?”

  3. Apply Use it on a flight

    “Your radio fails five miles from a towered airport in good weather. What do you do?”

4 · Common mistakes

  • Rehearsing nothing before keying the mic.

    Long, hesitant calls block the frequency and invite mistakes.

    Instead: Think "who, who, where, what", then key the mic.

  • Reading back with only a call sign.

    A controller can’t catch a misunderstanding you didn’t say back.

    Instead: Read back runway assignments, hold-short instructions, altitudes and headings in full.

  • Forgetting the light gun signals.

    They’re the only way the tower can talk to you when the radio fails.

    Instead: Keep a card on your kneeboard and review it before flights to towered airports.

5 · Quick check

Answer, then reveal. Flag anything you want to see again.

  1. 1. What does a steady red light mean on the ground, and in the air?

  2. 2. What does a flashing red light mean in the air?

  3. 3. What transponder code do you squawk for lost communications?

  4. 4. What instructions must you read back?

  5. 5. What do red Takeoff Hold Lights mean?

  6. 6. Within how many days is the written NTSB report due after an accident?

  7. Scenario7. You’re NORDO in the pattern at a towered airport and get a steady green light on final. What do you do?

Trained it? Now prove it: practice communications, light signals, and runway lighting systems out loud with our examiner.

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Connect it

One situation that runs across this lesson and its neighbors in the same ACS area. Decide first, then check.

Connect it · Airport Operations

You're inbound to a towered Class D airport and were told to enter a left downwind for Runway 24. Then your radio stops working.

How do you join the pattern and get a landing clearance with no radio? Decide, then see the worked answer

First troubleshoot: volume and squelch, the frequency, the headset and audio panel, and the second radio if you have one. If it's still dead, squawk 7600 and work out which case you have. Receiver out (you can still transmit): stay outside or above the Class D until you know the direction and flow of traffic, tell the tower your type, position, altitude and that you intend to land, ask to be controlled with light signals, and report again 3 to 5 miles out as you join. Transmitter out (you can still hear): stay outside or above until you know the flow, monitor the tower frequency, then join the pattern and keep the tower in sight for light signals. Both out: the same as transmitter out. To land without a radio in Class D, 14 CFR 91.129(d)(2) needs all three: basic VFR weather, visual contact with the tower, and a clearance to land, here by light signal. In the air: steady green, cleared to land; flashing green, return for landing, to be followed by a steady green before you land; steady red, give way to other aircraft and continue circling; flashing red, airport unsafe, do not land; alternating red and green, exercise extreme caution. Acknowledge in flight by rocking your wings in daylight, or blinking the landing or navigation lights at night; on the ground in daylight, by moving the ailerons or rudder. After touchdown: flashing red, taxi clear of the runway in use; flashing green, cleared to taxi; steady red, stop. Taxi clear and park, then call the tower by phone.

AIM 4-2-13, 4-3-13; 14 CFR 91.125, 91.129(d)

Brings together: Communications and Light Signals · Traffic Patterns

Teaching this? The instructor lesson plan →

Study aid, not FAA guidance. Sources: Aeronautical Information Manual (AIM); 14 CFR Part 91; 49 CFR Part 830; Chart Supplement; Private Pilot ACS (FAA-S-ACS-6C). Checked against current sources 2026-11-12.