IFR Lost Comms – Procedures and Regulations to Follow

FAR 91.185 – Regulations for Radio Failure

Should you experience a two-way radio failure during an IFR flight, Federal Aviation Regulation (FAR) 91.185 becomes your primary guide. It lays out a standardized set of procedures designed to keep your flight predictable and safe—both for you and for Air Traffic Control (ATC). This framework removes guesswork by defining clear actions for your route, altitude, and approach timing.

Beyond codifying the AEF route selection protocol, FAR 91.185 also dictates your altitude, mandating that you fly the highest of the following:

• The altitude assigned in your last ATC clearance.

• The minimum IFR altitude (MEA) for your route segment.

• The altitude ATC advised you to expect in a further clearance.

Upon reaching your clearance limit, timing the approach becomes critical. If the clearance limit is a fix where an approach begins, you must start your descent as close as possible to your Expected Further Clearance (EFC) time. If no EFC was provided, you must instead proceed based on the estimated time of arrival (ETA) from your filed flight plan.

While navigating under these rules, two actions are essential. First, immediately set your transponder to code 7600 to visually alert ATC of your situation. Second, continue trying to re-establish contact: cycle through your last assigned frequency, the emergency guard frequency of 121.5 MHz, or even attempt a relay through another aircraft.

The AEF acronym provides a clear, hierarchical checklist for determining your route of flight.

A — Assigned

Your primary obligation is to follow the route Assigned in your last ATC clearance. For example, if ATC cleared you “direct to the XYZ VOR, then via V123,” that is precisely the route you must fly.

V — Vectored

If you were being radar Vectored at the moment of communication loss, you must proceed directly to the fix, route, or airway specified in that clearance. For instance, if your last instruction was “fly heading 090 to intercept Victor 45,” you must fly that heading to the intercept and then continue along the V45 airway.

E — Expected

If you have neither an assigned route nor a vector, you must fly the route ATC advised you to Expect in a further clearance. A common example is hearing, “expect direct to the ABC VOR in ten miles.” Should you lose communications before that clearance is issued, this expected route becomes your active flight plan?

F — Filed

As a final resort, if none of the above conditions apply, you must revert to the route you Filed in your flight plan. This ensures a predictable, mutually understood flight path remains, even in the complete absence of recent ATC instructions.

Troubleshooting Lost Comes – Initial Steps

Before resorting to formal dot-coms procedures, always perform basic troubleshooting. Many communication failures stem from simple errors, and a calm, methodical approach can often resolve the issue and prevent an emergency.

Start with these simple physical checks, which resolve most communication issues:

• Check Frequency and Volume: Verify the correct frequency is selected, and the volume is up.

• Secure Connections: Ensure microphone and headset plugs are firmly seated.

• Switch Radios: If available, switch to a backup radio.

If the hardware appears functional, your next step is to re-establish contact.

Re-establishing Radio Contact

If initial troubleshooting fails, your immediate priority is to alert Air Traffic Control. Set your transponder to code 7600. This sends a clear, non-verbal signal that illuminates your radar target, instantly flagging your aircraft as having a radio failure and indicating you will follow dot-coms procedures.

However, squawking 7600 does not mean you should stop trying to communicate. Continue attempting contact on your last assigned frequency, as the problem could be intermittent. Periodically, switch to the emergency guard frequency (121.5 MHz) and broadcast your intentions “in the blind.” This means transmitting your position, altitude, and next actions, even without expecting a reply. Remember, you might still be able to receive; listen carefully for any instructions from ATC or other aircraft.

If contact cannot be restored, you must execute the formal procedures in FAR 91.185. Since your 7600 squawk has alerted ATC, your sole responsibility is now to fly a predictable route and altitude. This allows controllers to anticipate your actions and safely separate other traffic.

Lost Comes in VFR Conditions – What to Do

The complex IFR lost communication procedures simplify dramatically if you encounter Visual Flight Rules (VFR) weather conditions. Per FAR 91.185, whether the failure occurs in VFR or you encounter VFR after the failure, your course of action is clear: continue the flight under VFR and land as soon as practicable. This rule relies on the safety of “see and avoid,” freeing you from a rigid IFR route when you can visually navigate and maintain separation.

Even while proceeding visually, you must continue to squawk 7600 to keep ATC informed. The phrase “land as soon as practicable” does not imply an emergency; rather, it means you should select a suitable airport and land without undue delay. You are not obligated to continue to your filed destination if a closer, more appropriate airport is available. Your judgment as Pilot in Command is critical in selecting an airport, considering factors like weather, runway length, and available services.

As you navigate visually, continue your attempts to re-establish communication. Try the tower frequency of your destination airport or attempt to relay your intentions through another aircraft on 121.5 MHz. After landing safely, your final responsibility is to notify ATC of your arrival by the quickest means available, such as a phone call. This action officially concludes the dot-coms event and confirms you are safely on the ground.

Managing Approach Procedures During Lost Comes

After navigating to your destination or clearance limit using the AEF and MEA protocols, the final and most critical phase begins: the approach and landing. Your actions must remain completely predictable to ATC, which will be clearing airspace based on your expected flight path. To ensure this predictability, specific rules govern the timing of your approach from the holding fix.

FAR 91.185 is explicit on timing. If you have an Expected Further Clearance (EFC) time, you must begin your descent and approach as close as possible to that time. Should you arrive at the clearance limit fix early, you are required to hold until your EFC time. Without an EFC, you must commence the approach based on your filed Estimated Time of Arrival (ETA). This strict adherence to timing is what allows ATC to safely sequence other aircraft around your arrival.

After commencing the approach at the correct time, you must execute the published instrument approach procedure precisely as charted. There is no room for deviation. Fly the specified altitudes, headings, and courses to ensure you remain clear of obstacles and follow a known flight path. As you near the airport, be vigilant for visual signals from the control tower, such as light gun signals for landing clearance—a steady green light means you are cleared to land. Your 7600 squawk, combined with this by-the-book execution, gives ATC the certainty required to manage the airspace and guide you to a safe landing.

Conclusion – Key Takeaways for Pilots

An IFR dot-coms scenario is a significant challenge, but the procedures in FAR 91.185 turn a potential crisis into a manageable event. The entire regulation is built on one principle: making your actions predictable to ATC. Mastering these rules isn’t just a regulatory requirement—it’s a fundamental skill for safe instrument flying.

To ensure you are prepared, here are the key points to remember:

• Squawk 7600: Your first and most important action after troubleshooting fails. This immediately alerts ATC to your situation.

• Follow the AEF Route Protocol: Fly your route in this specific order of priority: the last Assigned route, then any radar Vectored route, followed by the Expected route, and finally, the route as Filed in your flight plan.

• Adhere to the MEA Altitude Rule: Maintain the highest of three possible altitudes: the Minimum IFR altitude for your route segment, the Expected altitude, or the last Assigned altitude.

• Time Your Approach Correctly: Upon reaching your clearance limit, begin your approach as close as possible to your Expected Further Clearance (EFC) time. If no EFC was issued, use your flight plan’s Estimated Time of Arrival (ETA).

• Attempt to Re-establish Contact: Continuously try to restore communication. Cycle through your last assigned frequency, the emergency guard frequency (121.5 MHz), and even consider asking another aircraft to relay a message.

• Execute the Published Procedure: Once you begin the approach, fly it exactly as charted. Remain vigilant for visual cues, such as light gun signals from the tower, to receive landing clearance.

Ultimately, adhering to these standardized procedures provides the critical predictability ATC needs to ensure a safe outcome. By following the regulations precisely, you create a clear flight path that allows the entire air traffic system to support you, even when you’re flying silent.