Definition
A specific ATC service provided at select towered airports without continuous radar coverage, in which the tower controller monitors the published tower frequency for distress calls or emergency transmissions from aircraft on final approach, even when the aircraft is not in direct two-way communication with the tower.
Plain English
An extra listening watch the tower keeps on its frequency so that a pilot on final approach who calls for help will be heard, even if they have not been talking to the tower.
Context Anchor
Seen in ATC and AIM glossary discussions of services provided while an aircraft is established on final approach.
Derivation
The term is built from plain English. 'Final' refers to the final approach segment of the landing pattern, and 'guard' has long been used in aviation and military radio practice to mean keeping a continuous listening watch on a frequency (as in 'guard frequency'). Together, the phrase describes a frequency watch focused on aircraft on final approach.
Why Pilots Care
Gives pilots an extra layer of safety by ensuring someone is monitoring their frequency during the critical landing phase and can initiate search-and-rescue or relay instructions if the pilot becomes lost or incapacitated.
Intuition Check
Do not read “guard” as a security person or a guarantee of protection. In this FAA use, it means ATC is monitoring the final approach and may issue a warning or instruction if needed.
Example Sentence 1
Because the field offers Final Guard Service, the tower controller heard the inbound pilot's mayday call even though the aircraft had not yet checked in.
Example Sentence 2
When the aircraft failed to report after the last handoff, the FSS activated Final Guard Service on 121.5 MHz to attempt contact and confirm the pilot’s status.