Light Gun Signals: ATC Light Signals Chart and Quiz

Light gun signals are the colored light beams a control tower aims at an aircraft when it cannot talk to the pilot by radio. In flight, steady green means cleared to land, flashing green means return for landing, steady red means give way to other aircraft and continue circling, and flashing red means the airport is unsafe, do not land. On the ground, steady green means cleared for takeoff, flashing green cleared to taxi, steady red stop, flashing red taxi clear of the runway in use, and flashing white return to your starting point. Alternating red and green always means exercise extreme caution.

Light gun signals chart

The meanings come from 14 CFR 91.125 and the Aeronautical Information Manual, paragraph 4-3-13. Each signal means something different depending on whether you are on the ground or in the air, so learn them as pairs.

Two patterns make the chart easier to hold in your head. Green signals give permission: cleared for takeoff, cleared to land, cleared to taxi, or come back around to land. Red signals hold you back: stop on the ground, keep circling in the air, or do not land at all. Flashing white has a single meaning, return to your starting point on the airport, and it applies only on the ground. A flashing green in flight is not a landing clearance; the steady green that follows is.

Light gun signals quiz

Ten questions drawn at random from our light gun signals bank, each with the answer and the regulation or AIM paragraph behind it.

How the tower uses the light gun

The AIM describes the light gun as a directive traffic control signal that projects an intense, narrow beam of red, white or green light. Towers use it to control aircraft, vehicles, equipment and people that have no radio, and also radio-equipped aircraft when radio contact cannot be established.

The AIM is candid about its limits:

• You may not be looking at the tower when the signal is aimed at you.
• A light can only approve or disapprove your anticipated next action. It cannot give you a taxi route, a runway assignment or traffic information.
• The only extra information it can carry is the general warning signal.

Alternating red and green: the general warning signal

FAA Order JO 7110.65, the air traffic controllers’ handbook, calls alternating red and green the general warning signal. Controllers use it when aircraft are converging and a collision hazard exists, when there is mechanical trouble the pilot might not be aware of, and when other hazards call for extra alertness, such as obstructions, a soft field or ice on the runway. It is not a prohibitive signal and can be followed by any other light signal. Look around, check your airplane, and keep watching the tower.

The column for vehicles and people

The full FAA chart has a third column for vehicles, equipment and personnel moving on the airport: steady green means cleared to cross, proceed or go; steady red means stop; flashing red means clear the taxiway or runway; flashing white means return to the starting point on the airport; alternating red and green means exercise extreme caution; and flashing green does not apply.

How to acknowledge a light signal

If you can receive but not transmit, or you have no radio at all, you answer the tower with the airplane itself:

These come from AIM 4-2-13 and match the receiver-only acknowledgment procedure in JO 7110.65 (paragraph 3-2-3). At night on the ground, the AIM adds a way to get the tower’s attention in the first place: turn on a landing light and taxi to a position clear of the active runway where the tower can see the light, and leave it on until you receive a signal.

Radio failure at a towered airport: what to do

Under 14 CFR 91.129(d), you must maintain two-way radio communications with the ATC facility, normally the tower, while you operate in Class D airspace. If your radio fails in flight under VFR, you may still operate and land if three conditions are met: the weather is at or above basic VFR weather minimums, you maintain visual contact with the tower, and you receive a clearance to land. Without a radio, that clearance is a steady green light. Here is a sequence built on the AIM’s procedures:

1. Rule out the simple causes. Check the volume, the selected frequency, your headset plugs and the audio panel before deciding the radio has failed.
2. Squawk 7600. AIM 6-4-2 says to set your transponder to code 7600 when you lose two-way radio communications, understanding that you may not be in radar coverage.
3. Stay outside or above the Class D surface area until you have determined the direction and flow of traffic.
4. If only your receiver has failed, tell the tower your aircraft type, position, altitude and intention to land, and ask to be controlled with light signals. About 3 to 5 miles from the airport, report your position and join the traffic pattern, then watch the tower for light signals. If you fly a complete pattern, report your position on downwind and/or turning base.
5. If only your transmitter has failed, join the traffic pattern, monitor the primary tower frequency shown on the sectional chart for landing or traffic information, and look for a light signal addressed to you.
6. If both have failed, join the traffic pattern and keep the tower in sight so you can receive light signals.
7. Land only with a landing clearance: by radio if you can still hear the tower, otherwise a steady green light. Acknowledge each signal as shown above, then fly a normal approach and landing.

The Pilot’s Handbook of Aeronautical Knowledge adds two practical points: no-radio (NORDO) arrivals are not accepted at busy airports, and if your radio quits it may be prudent to land at a nontowered airport with lower traffic volume, if practical. If you are flying under IFR, the lost communication rules in 14 CFR 91.185 apply instead. Whether a radio failure is an emergency depends on the circumstances, and the AIM makes that your determination as pilot in command; under 14 CFR 91.3(b), in an in-flight emergency requiring immediate action you may deviate from any Part 91 rule to the extent required to meet that emergency.

Departing without a radio

If your radio fails before you leave the parking area, the AIM says to make every effort to have it repaired. If you cannot, call the tower by telephone and ask for authorization to depart without two-way radio communications. If the tower approves, you will be given departure information and asked to monitor the tower frequency or watch for light signals, as appropriate. If the radio fails after you have left the parking area, watch the tower for light signals or monitor the tower frequency.

Light signals on the checkride

The private pilot Airman Certification Standards (FAA-S-ACS-6C) list ATC light signal recognition (PA.III.A.K3) and lost communication procedures (PA.III.A.K5) as knowledge elements of the Communications, Light Signals, and Runway Lighting Systems task, and deciding if and when to declare an emergency (PA.III.A.R2) as a risk management element. The ACS says knowledge and risk management elements are evaluated primarily on the knowledge test, and your examiner must retest any element you missed there, so a weak spot on light signals follows you to the checkride. Drill the quiz above until the pairs are automatic, then review our oral exam and checkride guides. The phraseology you use when the radio does work is in towered airport communications.

Gear for towered airport work

What you'll need

A kneeboard to keep the light gun card in view, plus the references and study guide that cover these rules, all from PilotMall.com.

Battleboard Kneeboard Tech Edition

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ASA FAR/AIM

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ASA Private Pilot Oral Exam Guide

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FAA Chart Supplement SE

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Light signals are one part of reading a towered airport. The rest of the picture is in our guides to airport signs, runway markings, airport lighting and PAPI and VASI lights.

Frequently asked questions

What does a flashing green light gun signal mean?

On the ground, flashing green means cleared to taxi. In flight, it means return for landing, to be followed by a steady green at the proper time. It is not a clearance to land.

What does a steady red light from the tower mean?

In flight, steady red means give way to other aircraft and continue circling. On the ground, it means stop.

How do you acknowledge a light gun signal?

In daylight, rock your wings in flight or move the ailerons or rudder on the ground. At night, blink your landing or navigation lights.

What transponder code do I set if my radio fails?

Set 7600, the code for loss of two-way radio communications. The AIM notes that you may not be in radar coverage, so keep watching the tower for light signals as you approach.

Can I land at a towered airport without a radio?

If your radio fails in flight under VFR in Class D airspace, 14 CFR 91.129(d) lets you land if the weather is at or above basic VFR minimums, you keep visual contact with the tower, and you receive a clearance to land, which comes as a steady green light. The PHAK notes that no-radio arrivals are not accepted at busy airports.

What does alternating red and green mean?

It is the general warning signal, meaning exercise extreme caution. It applies on the ground, in flight and to vehicles, and the tower can follow it with any other light signal.

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