Commercial pilot · ACS CA.III.A
Communications, Light Signals, and Runway Lighting Systems
Clear communication keeps everyone at the airport working from the same picture: on the radio, by light gun when the radio fails, and through the lights on the runway itself.
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.
Can’t miss
- •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)
What you should know
Frequencies and phraseology K1 · K2 · R1 · R3
- 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 K4 · K7
- 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 K3 · K5 · K6
- 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 K9
- 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 R2 · K8
- 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)
Scenarios
Decide what you would do first, then see the worked answer.
Cleared for takeoff, you line up and see red lights in the runway pavement ahead.
What do you do? See the worked answer
Don't take off. Red Takeoff Hold Lights mean the runway isn't safe; tell the tower you're holding because of the lights.
AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids
Your alternator fails on a night flight; the radios are getting weak.
What do you do? See the worked answer
Shed non-essential loads, tell ATC early what you need, and land at the nearest suitable airport. Plan for losing radios and lights, including pilot-controlled lighting.
Risk Management Handbook (FAA-H-8083-2A)
In cruise, you smell smoke but see no fire.
Do you declare? See the worked answer
Yes: a possible fire is an emergency. Declare, squawk 7700, follow the POH checklist, and land as soon as possible. Declaring early costs nothing; waiting can cost options.
AIM, Chapter 6, Emergency Procedures
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.
Now train it
Say it out loud, hear it asked, and take the quick check in this lesson’s practice pack. It tracks your shaky spots.
Got it?
When it feels solid, practice communications, light signals, and runway lighting systems out loud with our examiner.
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.
Watch (free, from the source)
Opens on the publisher’s site. AOPA courses may ask you to sign in with a free account.
Go to the source (free)
Teaching this? The instructor lesson plan →
Sources
- Aeronautical Information Manual (AIM): Chapters 2, 4, 6 and 7; Pilot/Controller Glossary
- 14 CFR Part 91: 91.125, 91.129(d)
- 49 CFR Part 830: NTSB notification and reporting
- Chart Supplement: your airports' frequencies and lighting
- Commercial Pilot ACS (FAA-S-ACS-7B): Area III
Study aid, not FAA guidance. Regulations change; check the current text at eCFR and the ACS. Checked against current sources 2026-11-13.