Definition
A condition in unmanned aircraft operations in which the command-and-control radio link between the remote pilot's control station and the unmanned aircraft is interrupted or lost, preventing the pilot from issuing commands to or receiving data from the aircraft. When this occurs, the unmanned aircraft executes a pre-programmed lost link procedure, typically involving a defined route, altitude, and action intended to keep the aircraft predictable to ATC and other airspace users until the link is restored or the flight is terminated.
Plain English
The radio connection between the person flying the drone (or other unmanned aircraft) and the aircraft itself has been broken. The aircraft can no longer be controlled in real time, so it follows a pre-set plan until the connection comes back or the flight ends.
Context Anchor
Seen in unmanned aircraft procedures, air traffic control coordination, and planned emergency actions for aircraft controlled from a remote station.
Derivation
Lost' in its ordinary sense of broken or no longer present, applied to the 'link' — the radio data connection between the pilot's control station and the aircraft. The phrase came into use as unmanned aircraft entered controlled airspace and ATC needed a standard term for this specific failure mode.
Why Pilots Care
Pilots of unmanned aircraft must follow specific lost link procedures to ensure the aircraft does not create a hazard in the airspace.
Grounding Statement
Picture a remotely controlled aircraft continuing on its planned backup path after its controller loses the control connection.
Intuition Check
Lost Link does not mean the aircraft is physically lost or missing. It means the control connection to the unmanned aircraft has been lost.
Example Sentence 1
The remote pilot reported a lost link, and the unmanned aircraft began climbing to its pre-filed lost link altitude on its way to the recovery point.
Example Sentence 2
Lost link procedures require the aircraft to hold its last assigned altitude until the connection is restored or a timeout occurs.