Lost Comms IFR – Procedures and Regulations

Understanding Lost Comes in IFR Flights

Losing two-way radio communication during an Instrument Flight Rules (IFR) flight—a “lost comes” event—is a serious situation that requires a clear, standardized response.

Once a communication failure is confirmed, the pilot’s first actions are to squawk 7600 on the transponder to alert ATC and immediately begin troubleshooting.

FAR 91.185 – Regulations for Communication Failure

Federal Aviation Regulation (FAR) 91.185 provides the official procedure for pilots during an IFR communication failure.

The regulation outlines a clear hierarchy for route selection, often remembered by the mnemonic AVE F :

• Assigned: Continue on the route last assigned by ATC.

• Vectored: If you were being radar vectored, fly direct to the fix, route, or airway specified in the vector clearance.

• Expected: In the absence of an assigned route or vector, fly the route ATC advised you to expect in a further clearance.

• Filed: If none of the above apply, follow the route filed in your flight plan.

Similarly, FAR 91.185 dictates the altitude to fly, a rule summarized by the mnemonic MEA. You must maintain the highest of the following three altitudes for the segment being flown:

• Minimum: The Minimum IFR Altitude (MEA) for the route.

• Expected: The altitude ATC advised you to expect at a certain time or fix.

• Assigned: The last altitude assigned by ATC.

An important exception to these rules applies in Visual Meteorological Conditions (VMC). If the failure occurs in VMC, or if VMC is encountered after the failure, the pilot must continue the flight under VFR and land as soon as practicable.

Transponder Code 7600 – What It Means

Squawking code 7600 is the universal, non-verbal method for declaring a two-way radio communication failure, a signal that immediately flags the aircraft’s data block on ATC radar screens.

This action informs ATC that the pilot will now proceed according to the strict procedures of FAR 91.185.

Procedures to Follow During Lost Comes

AVE FAME Principle Explained

To simplify these procedures in the cockpit, pilots often use the mnemonic AVE FAME, which merges the route hierarchy (AVE F) with the altitude hierarchy (AME) into a single, practical memory aid.

For example, if assigned 8,000 feet with a Minimum IFR Altitude (MEA) of 9,000 feet, you must climb to 9,000. If ATC also advised you to “expect 12,000 feet in ten minutes,” you would maintain 9,000 feet and then climb to 12,000 feet at the appropriate time.

Navigational Aids and Backup Communication

Successfully handling a lost comes event depends on using backup systems and navigational aids effectively. They are essential for maintaining situational awareness and following the route and altitude rules of FAR 91.185.

Once it’s clear that communication is lost, your focus shifts entirely to navigation. Following the route determined by the AVE F mnemonic now depends completely on your navigational equipment.

• *VOR (VHF Omnidirectional Range):* A reliable ground-based system for navigating along designated airways or to a specific fix.

• *GPS (Global Positioning System):* Provides superior situational awareness and simplifies direct-to-fix navigation or following a complex flight plan route.

Using these tools effectively ensures you can fly the required route with precision and predictability, allowing ATC to keep other aircraft safely out of your way.

Real-World Scenarios of Lost Comes

A real-world scenario illustrates how a pilot can manage a lost communications event with discipline and precision.

Imagine an IFR flight at 9,000 feet, recently vectored to 090 degrees to intercept an airway. Suddenly, the radio goes silent. After confirming the failure, the pilot’s first action is to squawk 7600.

Following the AVE F rule, the pilot flies the 090-degree vector to intercept the airway and then continues on the last assigned route. For altitude (AME), the pilot maintains 9,000 feet, as it is the highest of the minimum, expected, or assigned altitudes for that segment.

This predictable course of action allows ATC to anticipate the flight path and safely vector other aircraft, highlighting how FAR 91.185 creates a vital safety net built on predictability and pilot discipline.

Handling Lost Comes in VFR Conditions

While operating under VFR, the pilot must keep the transponder on code 7600. This maintains ATC’s awareness of the communication failure, allowing them to provide traffic advisories to other IFR aircraft.