Light Gun Signals – The Complete Guide to ATC Lights

Your radio dies five miles out. You can see the tower, and they can see you, but the frequency that should be crackling with instructions has gone silent.

So how do you land?

You look to the tower for a light gun signal. Light gun signals are beams of colored light — green, red, or white — that air traffic control shines at an aircraft to send clearances and instructions when two-way radio contact isn’t possible. When your radio fails, or you’re flying an aircraft without one, controllers switch to these signals — steady, flashing, or alternating — and each one’s meaning depends on whether you’re in the air or on the ground.

Below, we’ll walk through every light gun signal, what each one means both in flight and on the ground, and exactly how to respond.

Free Private Pilot Study Sheet

Grab a printable PDF that highlights must-know PPL topics for the written test and checkride.

• Airspace at-a-glance.
• Key regs & V-speeds.
• Weather quick cues.
• Pattern and radio calls.

Get the Free Study Sheet

Key Takeaways

• Light gun signals are a visual means of delivering instructions without radio.
• Three colors, in steady or flashing modes, create 10 distinct messages.
• Signal meanings change based on whether you’re airborne or on the ground.
• The ways to acknowledge signals will vary by aircraft type and time of day.

What Are Light Gun Signals?

In aviation, light gun signals are a backup communication system that air traffic control (ATC) uses when radio contact isn’t possible. 

They’re directed beams of colored light that ATC controllers shine from the tower using a handheld device.

Controllers point this device directly at your aircraft from the tower window. From the air, you’ll see a clear visual code that should tell you what to do next. 

But when will you even use these light gun signals, realistically? 

If you run into complete radio failure during flight, or when your aircraft isn’t equipped with a radio at all, you’ll need to know what those colored lights from the tower mean.

And they’re not just for aircraft, either. ATC can also use them for ground vehicles, equipment, and personnel operating on the airport surface without radio capability. 

The rules in 14 CFR 91.125 will tell you the exact meanings of each signal. Meanwhile, you’ll find the proper procedures in AIM 4-3-13 (Traffic Control Light Signals).

What Colors Can a Light Gun Emit?

The light gun can emit three distinct colors: red, white, and green. Just three, because the information needs to be simple and unambiguous. 

These colors are all in contrast with each other and should be easily identifiable. It’s also why your color vision gets tested on your medical exam.

Each of these three colors can be displayed in two ways: steady or flashing. A steady beam holds constant, while a flashing beam blinks on and off. 

What’s interesting, though, is that the same signal can mean different things depending on the context. 

What’s meant for aircraft on the ground doesn’t always apply to aircraft in the air and to personnel on the ground. That makes for ten distinct meaningful patterns!

Where Do I Look for Light Gun Signals?

So, where should you direct your attention? The signal comes from a handheld directional lamp that the ATC operates. Your eyes should go straight to the control tower cab windows. 

ATC signal light guns are typically specified with a center beam brightness of 180,000 to 200,000 candela. It should be visible for roughly 4 miles in clear daylight conditions. 

You’ll see the signal as a bright, focused beam of colored light coming from the tower windows. 

It won’t flood your cockpit like a searchlight. But when the controller has you locked in, the colored beam should be clearly visible against the tower’s background. 

During daylight operations, watch the tower carefully when you’re expecting a signal. The beam stands out best when you’re actively looking for it. 

It’ll be easier to spot if you know which window the controller typically uses for light gun operations.

At night, the signal becomes significantly more visible. Just keep an eye on the tower to catch it when it’s first transmitted.

That sounds impressive, but don’t get too complacent. The beam is highly directional, meaning the controller must point it precisely at you for you to see it. If you don’t know where to look, you’re definitely going to miss it. 

Do you know where the tower is? To save yourself precious time, commit the airport diagram to memory before every flight. 

Why Do I Need to Know Light Gun Signals?

You might find yourself in a situation where knowing your light gun signals becomes imperative, and maybe even life-saving.

You may fly an aircraft without radio equipment installed at all. But perhaps (and more crucially) your radio or the tower’s radio could fail in the middle of your flight.

You Don’t Have a Radio in Your Aircraft

Can you legally fly without a radio? Yes, but there are (as expected) very tight restrictions that you’ll need to consider. 

You can operate in Class E and Class G airspace without radio equipment, and a NORDO flight could even be practical for certain operations.

Some airfields will still need to relay key information to the pilot, so you’ll need to know and remember your light gun signals. 

If you need to use a towered airport, you’ll rely entirely on light gun signals for clearances and instructions.

Keep in mind that all of these would be true only if you have permission from ATC.

The Tower or Aircraft Has Suffered a Radio Failure

And while it’s exceptionally rare, two-way radio communication failure does happen from time to time. Your radio might fail, or in very rare cases, the tower’s radio equipment might malfunction. 

When this happens, you should adjust the transponder to reply on Mode A/3, Code 7600. Hopefully, your transmitter still works, and that’ll alert controllers about your communication failure. 

You’ll find the detailed procedures in AIM Section 6-4. But just remember, when you’re approaching the airport, safety might come down to how well you understand the tower’s light gun signals.

Do Light Gun Signals Only Apply to Aircraft?

Nope. The FAA uses light gun signals to control everything moving around an airport without radio communication. That includes those operating a ground vehicle. 

Airport maintenance trucks, fuel vehicles, and ground crews all watch for the same colored lights without radio communication.

But do the signals mean the same thing for ground vehicles and aircraft? Mostly, yes. 

A steady red light means stop, for both taxiing aircraft and trucks on the ground. Steady green means proceed. 

A flashing white light tells you to return to your starting point. Both ground vehicles and aircraft follow that instruction in the same way.

There’s just one difference: flashing green has no meaning for ground vehicles, only for aircraft.

All Light Gun Signals Explained

That brings us to the heart of our discussion. So, what do these colored signals mean for you, in your aircraft?

Steady Green

A steady green light is a constant, unblinking beam of green. This is your primary clearance signal in both environments. 

On the Ground

On the ground, it means you’re cleared for takeoff. You’re authorized to enter the runway and depart when ready. 

In Flight

Steady green means cleared to land when you’re in the air. The runway is yours, though you should still verify it’s actually clear before touching down.

Flashing Green

A flashing green light blinks on and off repeatedly. This signal has quite a distinct meaning between ground and flight operations. 

On the Ground

Flashing green means cleared to taxi. You can start moving, but you’re not cleared for takeoff yet. 

In Flight

In the air, flashing green means return for landing. Then, wait for steady green at the proper time. Come back to the pattern and watch for that steady green clearance. 

Steady Red

A steady red light is a constant red beam. This is your stop signal with slightly different applications. 

On the Ground

Steady red means STOP. Hold your position immediately and don’t move until you receive a different signal. 

In Flight

A steady red in the air means you should give way to other aircraft and continue circling. You’re not cleared to land, so keep flying the pattern and watch for traffic. 

Flashing Red

A flashing red light blinks rapidly. This is your safety warning signal with urgent meanings in either context. 

On the Ground

Flashing red means taxi clear of the runway in use. Get off the active runway now. 

In Flight

For aircraft in flight, it means the airport is unsafe; do not land. Something is wrong with the airport surface, so do not attempt to land. 

Flashing White

A flashing white light blinks repeatedly. This signal only applies on the ground. It means you should return to your starting point at the airport. The controller wants you back where you began. 

Alternating Red and Green

If you see a signal alternating between red and green, it means you should exercise extreme caution. 

This is the only light gun signal with universal meaning. On the ground or in the air, the message is the same. 

Something unusual is happening, and you need to be extremely careful. It’s the general warning signal that advises the pilot to be on alert.

What situations could call for this signal? You might be on a collision course with another aircraft. Or, there could be mechanical trouble present that you’re not aware of.

These conditions might include obstructions on the field, soft ground that could affect your movement, ice on the runway, or similar hazards that make your normal operations riskier than usual. 

The alternating lights are your signal to proceed carefully. Then, stay ready for whatever signal comes next.

How to Respond to Light Gun Signals

Okay, message received. You’ve won half the battle. Now, how do you tell the controller that you saw it and understood? 

With a receiver solely working, you can only show, instead of tell. And your way of doing so will differ by the time of day and aircraft type.

Be ready to follow these instructions from the tower, according to FAA Order 7110.65BB Section 3-2-3.

Between Sunrise and Sunset

During daylight hours, fixed-wing aircraft acknowledge tower transmissions or light signals by moving the ailerons or rudder when on the ground.

While in flight, stay out of or above Class D airspace until you’ve determined the traffic flow. Then, acknowledge by rocking your wings.

You can also do this without a working radio entirely. Per AIM 4-3-13(e), if you see the light gun signals, move your ailerons or rudder.

The controller will see your control surfaces deflect or your wings waggle. That’s their confirmation that you received the message.

For helicopters hovering during daylight hours, turn in the direction of the controlling facility. Then, flash the landing light or rock the tip path plane. 

In flight, helicopters should make shallow banks in opposite directions. Then, either flash the landing light or rock the tip path plane.

Between Sunset and Sunrise

At night, fixed-wing aircraft acknowledge by blinking the landing or navigation lights. The same goes even if your receiver isn’t onboard or is inoperative.

Your control surfaces are nearly invisible in darkness, so lights become your primary means of communication. A few quick flashes tell the controller everything they need to know.

Helicopters at night should acknowledge by flashing either the landing or the search light. Either one works, so use whichever you have available and is most visible to the tower.

Light Gun Signals Cheat Sheet (Printable)

Here’s a clear and simple light gun signal cheat sheet for aircraft. You never know when it’ll come in handy, but you don’t want to wish you’d printed it out when you had the chance.

Print out this table and keep it in your pocket or flight bag.

Memory Tricks for the Written Test

Struggling to keep all these signals straight? They’ll start to make sense when you imagine them as traffic lights for aircraft. 

Green means go, and red means stop. Everything else is a variation on that.

As mentioned, steady green means a full go. You have complete clearance for what you’re trying to do.

In the air, you’re cleared to land. On the ground, you’re cleared for takeoff.

A flashing green is your precursor to go. You’re getting close, but you’re not there yet. 

When you’re in the air, it means return for landing and watch for that steady green when you’re actually cleared. 

On the ground, you’re cleared to taxi. It’s movement, but not departure.

A steady red means a firm “no.” In the air, continue circling and give way to other aircraft. You’re not cleared to land yet, so keep flying the pattern. 

On the ground, it means exactly what you’d expect. Stop moving and hold your position.

A flashing red light is your warning signal. It flashes to immediately grab your attention, and it conveys urgency.

In the air, there are hazards at the airport, and you should land somewhere else. On the ground, you should taxi clear of the runway immediately.

Flashing white only applies to aircraft on the ground. When you see it, taxi back to your original starting point. The controller wants you back where you began, possibly the apron if that’s where you started.

Alternating red and green has the same meaning wherever your aircraft is. There are dangers you may or may not know about. 

It’s your reminder to stay alert, assess your situation, and exercise extreme caution.

Frequently Asked Questions

What Does a Steady Red Light from the Control Tower Mean?

A steady red light has different meanings depending on where you are. 

On the ground, it means stop immediately and hold your position. In the air, it means give way to other aircraft and continue circling until your next instruction.

What Does Alternating Red and Green from the Control Tower Mean?

Alternating red and green is the only light gun signal with universal meaning, and that’s to exercise extreme caution. 

This general warning signal tells you something unusual is happening, on the ground or in the air. It advises you to be on alert for potential hazards.

What Does a Flashing White Light Signal Mean to an Aircraft on the Ground?

Flashing white means return to your starting point at the airport. The controller wants you back where you began. 

This signal only applies to aircraft on the ground and has no meaning for aircraft in flight.

Can You Fly Without a Radio at a Towered Airport?

Yes, but you need prior coordination. If your radio fails before you leave the parking area, call the tower by telephone. Request authorization to depart without two-way radio communications. 

If the tower gives you authorization, you’ll receive departure information. Keep watch for light signals.

Do Light Gun Signals Apply to Drones?

Light gun signals don’t apply to your Part 107 operations. Instead, you’ll use digital authorization systems like LAANC and DroneZone.

And if you’re flying in Class B, Class C, Class D airspace, or within the lateral boundaries of the surface area of Class E airspace designated for an airport, you’ll need clearance from ATC. 

The system is meant for manned aircraft with pilots who can see and acknowledge tower lights. It’s a model that doesn’t work for remote pilots controlling drones from the ground.

Conclusion

That radio failure five miles out probably won’t happen to you. But if it does, you don’t want to get caught fumbling through your ATC light gun signals while you’re trying to fly.

Keep a reference card in your flight bag where you can actually find it when every second counts. Also, don’t forget to review the light gun signals before your next flight review or checkride.