Code 7400 may be displayed 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
a. Determine the lost link procedure, as outlined in the Special Airworthiness Certificate or Certificate of Waiver or Authorization (COA).
b. Coordinate, as required, to allow UAS to
execute the lost link procedure.
c. Advise Front Line Manager (FLM), when
feasible, so the event can be documented.
d. 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 J0 7110.65 Chapter 10, Section 1,Para 10−1−1(c).
Consider an auto-acquired aircraft as identified
when the data block is displayed and is visible to you, and one of the following conditions exist:
1. The radar or beacon identification procedures
have been used to confirm the identity of the tagged target.
2. The aircraft is being handed off using a NAS
automated system and one of the following does not appear in the data block: "CST", "NAT", "NT", "AMB", "OLD", "NB", "TU", "AM", "OL", or
b. Use the data block to maintain target identity
unless it is in a coast status or displaced from the
c. A displaced data block must be updated at all
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