Instrument rating · ACS IR.VII.A
Loss of Communications
When the radios go quiet, you fly a predictable plan. This lesson covers getting comms back, and if you can’t, the route, altitude and approach timing in 91.185.
Why this one matters
Lost communications in cloud feels like an emergency, but the rules are designed so that ATC can predict what you will do and keep everyone else away. Knowing the 91.185 sequence cold turns a frightening silence into a planned flight, and recognizing a simple fix (a volume knob, a headset plug) often ends it in seconds.
Can’t miss
- •Squawk 7600 and try to re-establish contact: check the radio and headset, try the last frequency, the next one, Flight Service, 121.5, or a relay.(AIM 6-4-1, Two-way Radio Communications Failure)
- •If you’re in VFR conditions or get into them, stay VFR and land as soon as practicable.(14 CFR 91.185)
- •In IFR conditions, route AVEF: the Assigned route; if being radar vectored, direct from the point of radio failure to the fix, route or airway you were vectored toward; in the absence of an assigned route, the route ATC said to Expect; in the absence of that, as Filed.(14 CFR 91.185)
- •Altitude, for each segment, the highest of: the last assigned; the minimum altitude for IFR on that segment (the MEA, or a MOCA, MCA or 91.177 altitude where those apply); or the altitude ATC said to expect, once you reach the time or fix given for it. An expected lower altitude never authorizes a descent.(14 CFR 91.185)
- •If the clearance limit is where an approach begins, start the descent and approach as close as possible to the EFC, or with no EFC, to your ETA (departure time plus the filed or amended time en route). Arriving early, hold there until that time.(14 CFR 91.185)
- •If the clearance limit isn’t where an approach starts, leave it at the EFC (or on arrival if none), go to an approach fix, and start the descent and approach as close as possible to your ETA.(14 CFR 91.185)
What you should know
Recognize and try to fix it K1 · R1
- Causes: a radio or electrical failure, a stuck mic, the wrong frequency, volume or squelch, a headset problem, or flying out of range.(AIM 6-4-1, Two-way Radio Communications Failure)
- Aviate first: fly the airplane or engage the autopilot. Then the simple checks: volume, squelch, the audio panel, the headset jack, the other radio and the last frequency. Don't keep resetting a tripped circuit breaker.(AIM 6-4-1, Two-way Radio Communications Failure)
- Try Flight Service, 121.5, another aircraft to relay, or a phone if you have signal. Listen on a VOR frequency; ATC may transmit there.(AIM 6-4-1, Two-way Radio Communications Failure)
- Squawk 7600 so ATC knows.(AIM 6-4-1, Two-way Radio Communications Failure)
The 91.185 plan K1 · R2
- VFR conditions: continue VFR and land as soon as practicable. That doesn’t mean "at once"; it means the first sensible airport.(14 CFR 91.185)
- Route: the assigned route; if vectored, direct from the point of radio failure to the fix, route or airway you were vectored toward; in the absence of an assigned route, the route ATC said to expect; in the absence of that, the filed route.(14 CFR 91.185)
- Altitude, for each segment: the highest of the last assigned, the minimum IFR altitude for the segment, or the expected altitude once you reach the time or fix where it applies. Climb to a higher expected altitude only then; it doesn't apply before.(14 CFR 91.185)
- Approach timing: at an approach fix, begin descent and the approach as close as possible to the EFC, or if none, to the ETA from departure time plus the filed or amended time en route; hold if you get there early. At a clearance limit that isn't an approach fix, leave it at the EFC (or on arrival) and start the approach as close as possible to the ETA.(14 CFR 91.185)
- Follow 91.185 so ATC can predict you, unless an emergency requires you to deviate (91.3(b)). You decide whether the failure is an emergency, and use good judgment in situations the rule doesn't cover.(AIM 6-4-1, Two-way Radio Communications Failure; 14 CFR 91.3(b))
On the flight
ACS standards
- Recognize a simulated loss of communication, simulate actions to re-establish it, decide whether to continue or divert, and determine when to begin an approach.(Instrument Rating ACS (FAA-S-ACS-8C), IR.VII.A.S1-S4)
What your instructor is watching for
Your instructor watches for quick troubleshooting, 7600, a clear statement of route and altitude for each segment, and the right approach time.
Scenarios
Decide what you would do first, then see the worked answer.
You lose comms in IMC while being vectored to the final approach course.
What route do you fly? See the worked answer
Direct from the point of radio failure to the fix, route or airway I was being vectored toward, then the approach, at the highest of assigned and minimum IFR altitudes.
14 CFR 91.185
Silence for 5 minutes; then you notice the audio panel switched to COM 2.
What now? See the worked answer
Switch back, call ATC, apologize and confirm the clearance. A simple fix first.
AIM 6-4-1, Two-way Radio Communications Failure
You break out into clear VFR conditions halfway to your destination with no radio.
What do you do? See the worked answer
Stay VFR and land as soon as practicable.
14 CFR 91.185
Common mistakes
Panicking into a diversion.
ATC can’t predict you.
Instead: Follow 91.185 unless safety requires otherwise.
Using the wrong altitude.
Terrain or traffic.
Instead: Highest of assigned, MEA, expected, per segment.
Skipping simple checks.
Most "lost comms" is a switch or a plug.
Instead: Check volume, audio panel, headset first.
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 loss of communications out loud with our examiner.
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Go to the source (free)
Teaching this? The instructor lesson plan →
Sources
- 14 CFR: 91.185
- Aeronautical Information Manual (AIM): 6-4-1
- Instrument Rating ACS (FAA-S-ACS-8C): Area VII
Study aid, not FAA guidance. Regulations change; check the current text at eCFR and the ACS. Checked against current sources 2026-11-13.