Dealing With Lost Communications on an IFR Flight Plan

John Peltier

A communications failure can be a scary thing – even on a beautiful VFR day. But throw in some clouds, limited visibility, and mountainous terrain, and suddenly this can be absolutely terrifying! As a pilot, maintaining a cool head and knowing your procedures will ensure this situation doesn’t get any worse.


ATC has cleared you to RYANN via radar vectors as filed on your flight plan. Your last assigned altitude was 8,000 feet. On the way to RYANN, you determine that your radio will neither transmit nor receive. You are in visual meteorological conditions (VMC). Panicked? What do you do?

If you’re VMC, it’s actually not that complicated. Set your transponder to 7600 and proceed VFR, landing as soon as practicable. But what if you have your instrument rating, and you’re in instrument meteorological conditions (IMC)? You can’t just descend down through the clouds on your own, so what do you do now?

IFR chart for creating an IFR flight plan

There are three major things to take into consideration after setting your transponder to 7600. The three things you need to determine are you routing, altitude, and clearance limit.


Take a stroll down Avenue F. This is your mnemonic device – AVE F. Your routing priorities are, in order:

Assigned – your last assigned clearance by ATC

Vectored – your last assigned vector by ATC

Expected – your last expected clearance given by ATC

Filed – your IFR flight plan as filed with ATC

So, if you received radar vectors to a fix where you would then pick up the rest of your IFR flight plan, you proceed on that vector to that point and then pick up your routing as filed. In the case of this scenario, you would continue to RYANN and then to your next point as filed.


What’s that important altitude between fixes on IFR charts? The minimum enroute altitude, or MEA? This is your next mnemonic device – MEA. Your minimum altitude to maintain is the highest of:

Minimum enroute altitude – the MEA listed on the chart

Expected altitude – the altitude ATC said for you to expect in a further clearance

Assigned – the altitude last assigned by ATC in your last clearance

So in our scenario, ATC last assigned an altitude of 8,000 feet. But looking at our IFR chart we see that the MEA for our routing (if we were flying northwest) is actually 10,000 feet. We must fly the higher of these, so we’d have to initiate a climb to 10,000 feet.

Clearance Limit

You’re going to have to continue the flight and eventually land. So where and when are you going to do this? We need to figure out our clearance limit. Fortunately, our IFR flight plan has a final fix and an ETA to help us with this.

First, we need to know if ATC gave us an expected further clearance. This is something we receive if we’re holding due to ATC or other delays. If we’re holding at an Initial Approach Fix (IAF) then we commence our approach once we get to the time ATC gave us in the EFC. If we’re not at an IAF, then we leave our holding fix at the EFC, proceed to the IAF, and hold as necessary to commence the approach as close to our ETA as possible.

If we don’t have an EFC, proceed to an IAF if not there already and start the approach as close as possible to our ETA.

  • We have an EFC
    • Fix is an IAF: Commence approach at EFC
    • Fix is NOT an IAF: Proceed to an IAF at EFC and commence the approach at ETA
  • We don’t have an EFC
    • Fix is an IAF: Commence approach at ETA
    • Fix is NOT an IAF: Proceed to an IAF and commence the approach at ETA
In Conclusion

Enroute communications failures on an IFR flight plan isn’t as scary as it may seem as long as we know what to do. Just remember the three major ingredients we need to safely carry out our flight plan.



Clearance Limit

We go down AVE F for our routing, fly the MEA for our altitude, and go to an IAF for the approach at either our EFC or ETA. It’s really as simple as that.

You can check out FAR Part 91.185 for the actual regulations concerning communications failures on an IFR flight plan.

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