← Train

Commercial pilot · ACS CA.III.A · lesson pack

Communications, Light Signals, and Runway Lighting Systems

Watch (free, from the source)

Opens on the publisher’s site. AOPA courses may ask you to sign in with a free account.

Why this one matters

Misheard clearances, non-standard phrases and unannounced problems are behind many incursions and incidents. A commercial pilot is expected to sound and act like a professional on the radio, and to ask for help early, before a problem becomes an emergency.

1 · Know these cold

  • •Get frequencies from the Chart Supplement, the charts and ATIS, and have them set before you need them.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique))
  • •Standard phraseology from the Pilot/Controller Glossary; read back runway assignments, hold-short instructions, altitudes and headings.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique); Pilot/Controller Glossary (AIM))
  • •Light signals: steady green, cleared to land (air) or cleared for takeoff (ground); flashing green, return for landing, to be followed by a steady green at the proper time (air: not a landing clearance; land only on steady green) or cleared to taxi (ground: not a takeoff or runway-crossing clearance); steady red, give way and keep circling (air) or stop (ground); flashing red, airport unsafe, do not land (air) or taxi clear of the runway in use (ground); flashing white, return to starting point (ground); alternating red and green, exercise extreme caution.(14 CFR 91.125; AIM 4-3-13)
  • •Airport lighting: runway edge lights white (yellow for the last 2,000 feet or half the runway, whichever is less, on instrument runways); threshold lights green toward arriving aircraft, runway end lights red toward departing ones; centerline lights white, then alternating red and white from 3,000 to 1,000 feet remaining, then red. Taxiway edges blue, centerlines green. REIL: a synchronized flashing pair at the threshold. PAPI: two white and two red on glidepath.(AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids)
  • •Red runway status lights mean stop, even with a clearance: don't enter, cross or take off; contact the tower.(AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids)
  • •Declare an emergency early ("Mayday" for distress, "Pan-pan" for urgency, squawk 7700); you get priority and ATC's full help.(AIM, Chapter 6, Emergency Procedures)
  • •Notify the NTSB immediately after an accident or listed serious incident; file the written report within 10 days of an accident.(49 CFR 830.5, 830.15)

2 · The lesson

Frequencies and phraseology
  • Frequencies come from the Chart Supplement, sectional and terminal charts, and ATIS. Load and label them on the ground.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique))
  • On first contact, say the ATIS you have ("with information Bravo"). Read back with your call sign every hold-short instruction, takeoff and landing clearance, runway assignment, and assigned altitude and heading. If you didn't hear it, say "say again"; never read back a guess.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique); AIM 4-4-7)
  • Listen first, think, then transmit briefly: who you're calling, who you are, where you are, what you want.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique))
  • Use the Pilot/Controller Glossary words ("unable", "say again", "wilco"). Non-standard phrases, like "with you" or "taking the active", are how misunderstandings start.(Pilot/Controller Glossary (AIM))
  • If a clearance is unclear or you can't comply, say so ("unable") and ask; never guess.(AIM, Chapter 4, Section 2 (radio communications phraseology and technique))
Transponder and radar assistance
  • Run the transponder with altitude reporting whenever you fly; it is required in Class A, B and C, within 30 nm of a Class B primary airport from the surface to 10,000 MSL, above Class B and C within their lateral limits up to 10,000 MSL, and at and above 10,000 MSL except at or below 2,500 AGL (91.215); ADS-B Out has a similar list (91.225). 1200 for VFR unless assigned; IDENT only when asked. Special codes: 7500 hijack, 7600 lost comms, 7700 emergency.(AIM, Chapter 4 (air traffic control: services, airport operations); 14 CFR 91.215, 91.225)
  • Radar services include traffic advisories, safety alerts, and vectors when lost or in trouble. Ask for flight following on cross-countries; it doesn't replace see-and-avoid.(AIM, Chapter 4 (air traffic control: services, airport operations))
When the radio quits
  • Check the simple causes: volume, squelch, frequency, audio panel, headset jacks, a stuck mic, the avionics master, and the electrical system (a failed alternator drains the battery).(AIM, Chapter 4, Section 2 (radio communications phraseology and technique))
  • VFR conditions: squawk 7600, stay VFR, land as soon as practicable. At a towered airport, stay outside or above the Class D until you know the traffic flow, then join the pattern keeping the tower in sight and watching for light signals. Land only with basic VFR weather, visual contact with the tower, and a steady green.(AIM 4-2-13 and 6-4-1; 14 CFR 91.129(d)(2))
  • Partial failures: if only the receiver is out, transmit your intentions in the blind and ask for light signals; if only the transmitter is out, listen and follow the tower's instructions, acknowledging as below.(AIM 4-2-13)
  • In IFR conditions, 91.185 applies instead: route as assigned (or direct to where you were vectored), else expected, else filed; altitude the highest of last assigned, the minimum IFR altitude for the segment, or the expected altitude; and time the approach from the EFC or your ETA.(14 CFR 91.185)
  • Acknowledge light signals: in flight, rock the wings by day or flash the landing or navigation lights at night (never rock the wings on final); on the ground, move the ailerons or rudder by day, or flash the landing or taxi lights at night.(AIM 4-3-13)
  • Know the light gun signals cold, in the air and on the ground.(14 CFR 91.125)
Runway status lights
  • Runway Entrance Lights glow red at a taxiway when the runway isn't safe to enter or cross; Takeoff Hold Lights glow red on the runway when it isn't safe to take off. Stop and contact the tower even with a clearance.(AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids)
  • Runway Intersection Lights glow red on a runway at an intersection when it's unsafe to cross the other runway. FAROS flashes the PAPI to warn an arriving pilot the runway is occupied: tell the tower and be ready to go around.(AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids)
  • The lights work automatically from surveillance data; they add a check, they never replace a clearance.(AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids)
  • Pilot-controlled lighting at many nontowered airports: key the mic on the published frequency (usually the CTAF) 7 times within 5 seconds for highest intensity, 5 for medium, 3 for lowest. Start with 7. The lights stay on 15 minutes from the last activation, so key them again before final.(AIM 2-1-8; Chart Supplement)
Emergencies and NTSB reporting
  • Declare when you are, or think you may be, in distress or urgency. Declaring early gives you priority and options; there's no penalty for asking for help you needed.(AIM, Chapter 6, Emergency Procedures)
  • An accident happens between the time anyone boards with the intention of flight and everyone has got off, and involves death, serious injury or substantial damage (both defined in 830.2, with their inclusions and exclusions). The operator must notify the nearest NTSB office immediately, by the fastest means, after an accident, a listed serious incident (such as a flight control failure, an in-flight fire or a midair collision), or an overdue aircraft believed to be in an accident.(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 an incident, 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 red light from the tower mean in the air, and on the ground?”

  2. Understand Explain why

    “Why is non-standard phraseology a risk?”

  3. Apply Use it on a flight

    “Your radios fail eight miles from a towered airport in VFR conditions, with passengers aboard. What do you do?”

4 · Common mistakes

  • Waiting to declare until there's no doubt.

    By then the options are fewer.

    Instead: Declare as soon as you think you might need priority; cancel later if it resolves.

  • Using non-standard phrases.

    They create misunderstandings.

    Instead: Use Pilot/Controller Glossary terms.

  • Forgetting the light gun signals.

    They're the only link with the tower when the radio fails.

    Instead: Review them before flights to towered airports.

5 · Quick check

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

  1. 1. What does a steady green light mean on the ground?

  2. 2. What transponder code indicates lost communications?

  3. 3. What do red Runway Entrance Lights mean?

  4. 4. When is the written NTSB report due after an accident?

  5. 5. Name three serious incidents that require immediate NTSB notification.

  6. Scenario6. You're NORDO in the pattern at a towered airport and get a flashing green on downwind. What does it mean?

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

Start a practice oral on this task

Your progress is saved in this browser. Create a free account to keep it on every device, with your shaky spots and mock oral results in one place.

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 arrive at 2300, after the tower has closed. The runway lights are off.

How do you communicate, light the runway and join the pattern? Decide, then see the worked answer

Check the Chart Supplement first: with the tower closed, the airspace usually reverts to Class E or G, you self-announce on the CTAF, and it gives the pilot-controlled lighting frequency. Start announcing about 10 miles out, then on downwind, base and final, and when you leave the runway. Work out the runway in use before you join: the AWOS or ASOS wind, what traffic is saying on the CTAF, and the windsock. Light the runway: on the published frequency, 7 clicks within 5 seconds for the highest intensity available, 5 for medium or lower, 3 for the lowest. Some systems have only one or two steps, so always key 7 first, then step down. The lights stay on for 15 minutes from the most recent activation, so key them again before final so they don't time out on short final. Be at pattern altitude, normally 1,000 feet AGL for propeller airplanes, before you enter. Enter on a 45° to the downwind, abeam the runway's midpoint, with left turns unless right traffic is published, and look hard for unlit traffic.

AIM 2-1-8 (Table 2-1-3), 4-1-9, 4-3-3; AC 90-66C; Chart Supplement

Brings together: Communications, Light Signals, and Runway Lighting Systems · 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; Commercial Pilot ACS (FAA-S-ACS-7B). Checked against current sources 2026-11-13.