FAR Ninety-One Point One Eighty-Five, the Lost Communications Procedure Hiding Behind Every Tower Endorsement, and the AVEF Route Priority That Only Makes Sense When Someone Explains the Why

FAR 91.185 is the Federal Aviation Regulation governing in-flight radio communication failure. It covers two distinct scenarios - losing comms in VFR conditions and losing comms under IFR - and understanding the logic behind each procedure is what separates a pilot who can apply the rule under pressure from one who just memorized a mnemonic.

What Should You Do First When Your Radio Fails?

Squawk 7600. That is the transponder code for lost communications, and it should be your first action after confirming the failure.

7600 is not 7700 (general emergency) or 7500 (hijacking). Lost comms is an equipment problem, not an emergency declaration. When controllers see that squawk on radar, they shift into lost-comms mode and begin routing other traffic around your position.

Before assuming a full radio failure, spend thirty seconds checking the obvious: a loose headset plug, volume turned to zero, the wrong frequency, a stuck push-to-talk. Try COM 2 if available. The formal lost comms procedure applies once you’ve genuinely confirmed the radios are dead.

How Do You Handle Lost Communications in VFR Conditions?

The regulation requires you to continue VFR and land as soon as practicable. That phrase matters - it does not mean as soon as physically possible. It means use sound judgment about where and when to land.

If you’re twenty miles from your destination with no complications ahead, completing to your planned airport is reasonable. If you’re inbound to busy airspace with traffic building around you, diverting to a nearby uncontrolled field may be the smarter call. The key is making a decision and acting on it, not continuing to fly indefinitely.

Avoid actions that complicate the situation. Don’t hunt through frequencies while flying. Don’t climb into a cloud layer. Keep the flight simple, stay in visual conditions, and get the airplane on the ground.

One critical restriction: if you lose comms outside Class Bravo or Class Charlie airspace before receiving a clearance to enter, you cannot enter. Those airspace classes require established two-way communication before entry, and a comm failure does not waive that requirement. Squawk 7600, reroute around the airspace, and land elsewhere.

Class Delta is different. Once you’ve established two-way contact and then lose it inside the Delta, the tower knows you’re already there and the light gun procedure applies.

What Are the Light Gun Signals You Need to Know?

When voice communication fails at a towered airport, the controller uses a light gun - a directional device projecting colored beams - to continue communicating with you. The tower hasn’t lost you. They can still see you, and the conversation continues in light.

Signals for aircraft in flight:

• Steady green - Cleared to land
• Flashing green - Return for landing
• Steady red - Give way to other aircraft and continue circling
• Flashing red - Airport unsafe, do not land
• Flashing white - Return to starting point on the airport
• Alternating red and green - Exercise extreme caution

Signals for aircraft on the ground:

• Steady green - Cleared for takeoff
• Flashing green - Cleared to taxi
• Steady red - Stop
• Flashing red - Taxi clear of the runway in use
• Flashing white - Return to starting point on the airport

The air and ground signals differ for several colors. Oral examiners frequently ask about both sets in a single question - mixing them up is one of the most common checkride mistakes on this topic.

To acknowledge a light gun signal in flight, rock your wings in daylight or flash your landing lights at night. The controller watches for that acknowledgment.

How Do You Fly a Lost Comms Pattern at a Towered Airport?

Fly a completely normal pattern. If the radio fails on downwind, squawk 7600, maintain normal spacing, and continue downwind, base, and final exactly as you would any other circuit.

On final, look toward the tower cab. When the controller sees you established with proper spacing, they’ll put a steady green on you. Rock your wings to acknowledge. Land. Exit the runway.

After shutdown, call the tower by phone. This is not a confession - it’s closing the loop. Tell them what happened and what you did. It keeps the incident record accurate and is the professional standard.

What Route Do You Fly Under IFR Lost Communications? (AVEF)

Under IFR, the entire instrument system depends on aircraft being where their clearances say they are. A comm failure without a defined procedure would make you a hazard to other IFR traffic. FAR 91.185 establishes that procedure in advance so both pilots and controllers can act independently and still produce predictable, separated traffic.

The route priority order is AVEF: Assigned, Vectored, Expected, Filed.

• Assigned - Fly the route in your last ATC clearance. This is your first choice.
• Vectored - If you were being radar vectored at the time of the failure, fly direct to the fix or airway you were being pointed toward and join it.
• Expected - If ATC told you to anticipate a specific routing or approach, proceed as though you received that clearance.
• Filed - If none of the above apply, fly the route in your filed flight plan.

The order moves from most specific to least specific. Each level reflects a different degree of precision about your intended path, but all four options are predictable - and predictability is what allows controllers to separate other traffic from you without a single word being spoken.

What Altitude Do You Fly Under IFR Lost Communications?

Fly the highest of three altitudes:

1. Your last assigned altitude
2. The minimum IFR altitude (MEA or MOCA) for your current route segment
3. The altitude ATC told you to expect in a further clearance

If you were assigned 8,000 feet, the MEA is 6,000 feet, and ATC told you to expect 10,000 feet in thirty miles - you climb to 10,000 feet. That is the highest of the three.

The logic is separation. ATC constructs their traffic picture above the highest altitude a lost-comms aircraft could legally be at under this procedure. Flying lower than the regulation requires doesn’t make you safer - it makes you unpredictable. When every pilot in a lost-comms scenario climbs to their highest applicable altitude, controllers can route other traffic above that level with confidence.

When Do You Begin the Approach Under IFR Lost Communications?

Timing is how ATC sequences traffic, and it’s what makes the entire procedure functional rather than theoretical.

If your clearance limit is the destination airport, begin the approach at your expect-further-clearance (EFC) time if one was given. If no EFC was given, begin at your estimated time of arrival (ETA) as derived from your filed or amended flight plan.

If your clearance limit is an intermediate fix, leave that fix at the EFC time. If no EFC was given, leave at your ETA to that fix.

If you’ve been holding at your clearance limit and the EFC time arrives with still no comms - leave the hold. The EFC time exists precisely to give you an instruction for that moment. Do not hold indefinitely.

This is one reason filing realistic time estimates matters. Under IFR lost comms, your filed ETA is the specific number ATC uses to keep other airplanes away from you.

Key Takeaways

• Squawk 7600 immediately upon confirming a radio failure. It signals a comm failure, not an emergency.
• In VFR conditions, land as soon as practicable - this demands judgment, not just speed.
• Light gun signals differ between aircraft in the air and on the ground. Know both sets; examiners ask about both.
• IFR route priority follows AVEF: Assigned, Vectored, Expected, Filed - most specific to least specific.
• IFR altitude selection is always the highest of assigned, minimum IFR altitude, or expected - because predictability is what maintains separation.