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Unmanned Aircraft Systems (UAS) Lost Link

JO 7110.65BB, Change 3, effective July 9, 2026 · Official text on faa.gov

Code 7400 may be transmitted by unmanned aircraft systems (UAS) when the control link between the aircraft and the pilot is lost. Lost link procedures are programmed into the flight management system and associated with the flight plan being flown.

When you observe a Code 7400 display, do the following:

Determine the lost link procedure, as outlined in the Special Airworthiness Certificate or Certificate of Waiver or Authorization (COA).
Coordinate, as required, to allow UAS to execute the lost link procedure.
Advise the OS/CIC, when feasible, so the event can be documented.
If you observe or are informed by the PIC that the UAS is deviating from the programmed Lost Link procedure, or is encountering another anomaly, treat the situation in accordance with FAA Order JO 7110.65 Chapter 10, Section 1, paragraph 10-1-1c.
Note
1. The available lost link procedure should, at a minimum, include lost link route of flight, lost link orbit points, lost link altitudes, communications procedures and preplanned flight termination points if the event recovery of the UAS is deemed unfeasible.
2. Each lost link procedure may differ and is dependent upon airframe and operation. These items are contained in the flight's Certificate of Authorization or Waiver (COA) and must be made available to ATC personnel in their simplest form at positions responsible for Unmanned Aircraft (UAs).
3. Some UA airframes (Global Hawk) will not be programmed upon the NAS Automation roll out to squawk
4. These airframes will continue to squawk
5. should a lost link occur. The ATC Specialist must apply the same procedures described above.