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IFR Lost Communication Procedures Explained: What to Fly, Where to Go, and When to Descend

Lost communications—commonly called “lost comms”—is one of the most heavily tested and most misunderstood IFR topics. While modern radios are highly reliable, IFR pilots must always be prepared to continue a flight safely, legally, and predictably if two-way communication with ATC is lost.


The FAA has provided clear rules for these situations, but they only work if pilots understand the logic behind them, not just the acronyms.


This post explains exactly what to do during IFR lost communications, using real-world context and checkride-ready explanations.



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What Counts as Lost Communications?

Lost communications occur when:

  • You cannot transmit to ATC

  • You cannot receive from ATC

  • Or both


Before assuming lost comms, pilots should:

  • Check volume and audio panel settings

  • Try another radio

  • Switch frequencies

  • Use the standby radio

  • Try another ATC facility

  • Attempt relay through another aircraft


If communication cannot be restored, lost communication procedures apply immediately.


The Regulatory Basis

In the United States, IFR lost communication procedures are defined in 14 CFR §91.185.


The regulation answers three critical questions:

  1. What route should I fly?

  2. What altitude should I maintain?

  3. When should I descend and approach?


Route Selection: The AVEF Rule

If you lose communications under IFR, fly the route determined by AVEF, in priority order:

  • A – Assigned

    • The route last assigned by ATC

  • V – Vectored

    • If being radar vectored, fly the direct route from the point of failure to the fix, route, or airway specified in the vector clearance

  • E – Expected

    • The route ATC told you to expect in a future clearance

  • F – Filed

    • The route filed in your IFR flight plan


Use the first applicable option in this order.


Altitude Selection: The MEA Rule (Highest Wins)

For altitude, fly the highest of the following three options:

  • M – Minimum IFR Altitude

    • MEA, MOCA (if applicable), MCA, or OROCA

  • E – Expected

    • The altitude ATC advised you to expect

  • A – Assigned

    • The last altitude assigned by ATC


This ensures:

  • Obstacle clearance

  • Navigation signal reliability

  • Traffic separation


If in doubt, the highest altitude is always correct.


Timing and the Destination Airport

Lost comms procedures differ depending on whether the destination has an instrument approach.


Destination With an Instrument Approach

If your destination has a published approach:

  • Fly the route per AVEF

  • Maintain altitude per MEA

  • Proceed to the Initial Approach Fix (IAF) or approach fix

  • Begin descent and approach at the:

    • Estimated Time of Arrival (ETA) from your flight plan, or

    • Expected Further Clearance (EFC) time, if given


Destination Without an Instrument Approach

If no approach is available:

  • Proceed to the destination

  • Descend to a safe altitude

  • Land as soon as practicable


ATC expects predictable behavior, not improvisation.


Transponder and Visual Signals

During lost communications:

  • Squawk 7600 on the transponder

  • Continue to monitor frequencies

  • Watch for:

    • Light gun signals

    • ATC instructions via text or relay

    • Changes in traffic behavior


Radar facilities will attempt to protect airspace around you.


Lost Comms While Being Radar Vectored

This is a common checkride scenario.


If communications are lost while being vectored:

  • Fly the direct route to the fix, airway, or route specified in the clearance

  • Do not continue the vector indefinitely

  • Resume the cleared route structure


This is where the V in AVEF applies.


Lost Comms on a STAR or Approach

  • Continue flying the published procedure

  • Comply with all altitude and speed restrictions

  • Fly the approach as charted

  • Do not improvise or shortcut unless safety requires it


Predictability is critical—ATC will anticipate your actions.


Common Pilot Mistakes

  • Flying the lowest altitude instead of the highest

  • Ignoring expected altitudes

  • Starting the approach early

  • Deviating from the filed route

  • Forgetting to squawk 7600

  • Confusing AVEF order


These errors are frequent causes of checkride failures.


Checkride Tip: Explain the Logic

Examiners are less interested in rote memorization and more interested in why the rules work.


A strong answer explains:

  • AVEF ensures ATC predictability

  • Highest altitude ensures safety and separation

  • Timing prevents conflicts in the terminal area


Real-World Perspective

Lost communications procedures are designed to:

  • Keep aircraft separated without talking

  • Allow ATC to “think like you”

  • Protect terrain, obstacles, and traffic

  • Get you on the ground safely


They are not about perfection—they are about predictability.


Final Thoughts

IFR lost communications can be stressful, but they don’t have to be dangerous. The system works when pilots:

  • Fly predictable routes

  • Choose conservative altitudes

  • Follow published procedures

  • Resist the urge to improvise


If you remember just two things:

  • AVEF for route

  • Highest of MEA for altitude


You’ll always have a safe, legal plan—even in silence.



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