IFR Lost Communications

All instrument pilots learn the rules (14 CFR §91.185) that apply if you lose two-way radio communications while operating under IFR. But most discussions of that regulation overlook three key paragraphs in the AIM and their practical implications.

Note: This original text for this post first appeared in the February 2018 issue of the American Bonanza Society magazine.

First, to review the basics, see 14 CFR §91.185 and the Instrument Flying Handbook (FAA H-8083-15B), which describes the details of the regulation in “Communication/Navigation System Malfunction” (p. 11-8).

To simplify matters, most of us employ a mnemonic such as Avenue F MEA to aid recall of the key details of the route and altitude to fly (assuming you are not flying in VMC, do not encounter VMC after losing two-way communications, and that you cannot hear or respond to ATC via voice over a navaid, squawking IDENT, turning to headings, or other means).

Avenue F (Route)

• Assigned: Last assigned heading, or—
• Vectored: Fly the last vector to the ATC-specified fix or route, or—
• Expected: Fly the route ATC last told you to expect (e.g., join an airway, feeder route, localizer, etc.), or—
• Filed: If you haven’t received an updated clearance or route from ATC, fly the route that you filed.

MEA (Altitude)

• The minimum en-route altitude for the segment of the route you’re flying, or—
• The expected altitude ATC told you to anticipate, or—
• The assigned altitude that ATC included in your original clearance

To the route and altitude, add timing, so that you arrive at your intended destination when ATC is expecting you, per the details in the regulation and the AIM.

To these guidelines, I add the specific lost communications procedures that are typically included as notes for published IFR departure procedures. For example, see the chart for the YELM THREE departure at the Olympia, WA (KOLM) airport.

Practical Advice from the AIM

Instructors and DPEs enjoy posing lost-communications scenarios that require careful parsing of 14 CFR §91.185 and scrutiny of IFR charts.

But in focusing on the regulation itself, we often overlook what is arguably the most important practical guidance for such situations, found in AIM 6−4−1: Two-way Radio Communications Failure.

The first three paragraphs of that section note that:

a. It is virtually impossible to provide regulations and procedures applicable to all possible situations associated with two-way radio communications failure. During two-way radio communications failure, when confronted by a situation not covered in the regulation, pilots are expected to exercise good judgment in whatever action they elect to take. Should the situation so dictate they should not be reluctant to use the emergency action contained in 14 CFR Section 91.3(b).

b. Whether two-way communications failure constitutes an emergency depends on the circumstances, and in any event, it is a determination made by the pilot. 14 CFR Section 91.3(b) authorizes a pilot to deviate from any rule in Subparts A and B to the extent required to meet an emergency.

c. In the event of two-way radio communications failure, ATC service will be provided on the basis that the pilot is operating in accordance with 14 CFR Section 91.185. A pilot experiencing two-way communications failure should (unless emergency authority is exercised) comply with 14 CFR Section 91.185….

Note also that the Instrument Rating ACS places lost communications procedures in section VII Emergency Operations. The standards for Task A in that section state that you must understand and demonstrate the:

Procedures to be followed in the event of lost communication during various phases of flight, including techniques for reestablishing communications, when it is acceptable to deviate from an IFR clearance, and when to begin an approach at the destination.

The AIM text recognizes and implicitly suggests several issues that you must consider if you lose two-way communications while operating IFR in IMC. For example:

• What caused the communications failure? Just broken radios? A fault somewhere in the electrical system?
• Will proceeding according to the regulation require you to continue the flight–perhaps for an extended time–over potentially hazardous terrain or through challenging weather?
• Are you currently operating within or near busy airspace, such as Class B? Will your cleared IFR route take you near or into such airspace?

Suppose, for example, that you lose communications after you level off westbound following a departure from Spokane International Airport (KGEG) in Washington state en route to Boeing Field (KBFI) in Seattle.

Your clearance will take you via V2 across the Cascade Mountains to Boeing Field (KBFI) in Seattle. You are not on fire or aware of any other issue with the airplane that demands an immediate precautionary landing. Weather at airports along or near your route is IMC but at or above published minimums for the approaches available to you.

Adhering to the letter of 14 CFR §91.185 would require you to continue along your last cleared route at the appropriate altitudes to arrive as close as possible to your ETA at KBFI.

But the introductory paragraphs to AIM 6-4-1 give you broad support to exercise your emergency authority as PIC.

For example, diverting to an airport such as Moses Lake (KMWH) and flying one of its many available approaches would be far more reasonable than continuing across the mountains and then descending into the congested airspace that surrounds Seattle—and perhaps holding near KBFI to arrive near your ETA.

Whether or not you continue strictly according to the regulations, ATC will clear the airspace around you until your intentions are clear and they’re able track you or confirm that you’re on the ground. Assuming that they can still observe you—even if only as a primary target on their traffic displays—they will be happy to watch you descend into a relatively quiet airport like KMWH rather than, like members of a curling team, furiously sweep the path in front you all the way to your filed and cleared destination.