Lost comms are high on the pilot stressful-scenario scale, but not because there’s anything inherently dangerous about not having radios.

Instead, it’s the complex set of rules to follow should you lose radio contact with ATC that keeps pilots up at night. 

Facing a radio communications failure is an excellent test of airmanship.

That is to say, it’s a situation where you must apply not only what you’ve learned from the books but also some common sense and problem-solving skills — aeronautical decision making.

It requires you to know the finer points of your equipment, troubleshoot, and develop the safest plan of action given your present conditions and what is legally required. 

Here are the steps to follow, including some common-sense things and the FARs. But remember, this scenario requires a pilot ready to think clearly, act carefully, and solve problems.  

If You Suspect Your Radio Has Failed, Troubleshoot First!

If you suspect you’ve lost contact with ATC, your first step must be to troubleshoot the problem. 

Many references will tell you to “immediately” do something, like change your transponder code, course, or altitude.

There’s no reason to assume that a loss or possible loss of radios is an emergency.

Pilots must fight this urge because nearly all radio failures are simple problems that can easily be fixed if you stop and think about them. 

The radio stacks in most aircraft are pretty complex.

Chief Engineer Montgomery Scott once said of the newest starships, “The more they overthink the plumbing, the easier it is to stop up the drain.”

Most avionics stacks include two radios, an audio panel, and an intercom system that all must be set correctly to transmit and receive. 

So, your first step needs to be checking all your settings. 

Check Your Audio Settings First

Can you hear anything in your headset?

Check that both plugs are still firmly in the panel.

Can you hear your passengers?

Check your headset’s volume. Try activating the overhead speaker and see if you can hear that.

Can you hear other transmissions on the same radio? Check the radio’s volume and squelch.

Check which radio is selected on the intercom panel. Has the problem occurred after a frequency change or hand-off? Try the last working frequency again. 

Confirm if You Can Transmit or Receive

Can others hear your transmissions?

Some radios have an indicator to show that they are transmitting; does that come on when you press the push-to-talk (PTT) button?

PTT buttons fail frequently; try pressing harder.

Can you use a hand mic to bypass the PTT button and headset? If you have two radios, try the other one. 

You haven’t lost communications if you’ve discovered that you can receive but not transmit.

ATC will try to contact you, and if you don’t answer, one of their first instructions will be, “If you can hear this transmission, squawk ident.”

If you’re in sight of the tower, they may ask you to rock your wings or flash your lights. These actions will allow you to acknowledge their instructions, so you don’t have a complete communications failure after all.

The opposite could also be true — maybe you’re transmitting just fine but can’t hear their replies.

If you think your unit is actually transmitting, continue stating your intentions. It’s called “transmitting in the blind” and lets ATC know what to expect from you.

Use common sense in busy airspace, as you might be stepping on other pilots every time you transmit. 

Not to beat a dead horse, but before you give up completely, check all those volume knobs one last time, okay?

If you can get nothing from your radios or you’ve had a complete electrical failure, what alternative communications devices could you employ?

Does anyone on board have a handheld aviation VHF radio in their bag? How about a cell phone? Call the tower and let them know your situation. 

Radio Failures While VFR (Or IFR in Visual Conditions)

If you followed that outline of troubleshooting, you probably solved your no radio situation. (Admit it, it was the volume knob, wasn’t it?)

But if you didn’t, you’ll have to start considering the regulations and best practices from the AIM.  

A good starting point is to use the only tool left to communicate what’s happening with you to the outside world. By putting 7600 in your transponder, you will be labeled “NO RADIO” on any radar scope that sees you. 

Evaluate Your Flight Conditions

You must evaluate your situation, whether you are flying IFR vs VFR, and the actual weather conditions.

The best situation, and one that you would ideally hope to occur no matter where you are or where you are going, is to have a communication failure while in VMC.

If so, you should keep the plane in VMC and continue flying VFR.

This even applies if you’re IFR but later encounter VFR conditions. If you’re in VFR, stay there and land as soon as practicable. This includes if you had the failure in Class A airspace.

Divert to Uncontrolled Airspace

If you can divert to an uncontrolled field, you will not have to deal with getting clearance to land via lightgun signals.

Remember that using a CTAF frequency is voluntary, so you don’t legally need a radio to operate at an uncontrolled field.

This would be the least stressful and likely safest for many pilots, especially considering how busy many towered fields are. Once you’re safely on the ground at an uncontrolled field, you can find someone to help you fix the radios.

Or, you could call your destination airport’s tower on the phone to make arrangements to arrive without radios. At least they’ll be expecting you that way.

Landing at a Towered Airport

If you proceed to a towered airport, diverting to the least busy, easiest-to-approach field makes sense. You might also consider how likely it is to get the problem fixed there.

You can signal your intent to land by entering a rectangular traffic pattern 500 feet above the highest pattern at the airport. If the airport has 1,000 AGL for light aircraft and 1,500 AGL for jets, you should enter a pattern at 2,000 AGL. 

Once inbound, watch the tower for light gun signals aimed in your direction. You can find the tower light gun signals in the AIM, Section 4-3-13. 

Color & Tyoe	When TAXIING	When in FLIGHT
Steady Green —-	Cleared for takeoff	Cleared to land
Flashing Green – – – –	Cleared to taxi	Return for landing (should be followed by steady green)
Steady Red  —-	STOP	Give way to other aircraft; continue circling
Flashing Red – – – –	Taxi clear of runway	Airport unsafe; do not land
Flashing White – – – –	Return to your starting point	Not used
Alternating Red/Green – – – –	Use caution	Use caution

FAA Light Gun Signal color graphic

Radio Failures When IFR in IMC (Instrument Flight in Instrument Conditions)

Radio failures while flying IFR in IMC require a detailed understanding of the regulations. You must do what is safe for the flight and what the controllers expect you to do next. 

To continue, you must plan what to do with your route and your altitude.

For the route, you must remember “AVE F” — an acronym to help you consider that you must fly the known route in this order:

• A – Assigned route (what you have been cleared for)
• V – Vectors (if you’re on radar vectors, proceed direct to that fix)
• E – Expected (if you were told to expect something)
• F – Filed (Lacking a clearance or expected clearance, proceed as filed on your flight plan)

For your altitude, you must remember “MEA.” Get immediately to the highest of your:

• M – Minimum enroute altitude (MEA) or appropriate off-route clearance altitude for the route you are flying
• E – Expected altitude
• A – Assigned altitude

These lost radio procedures are taken from the FAA AIM 6-4-1 and FAR Part 91.185