Definition
Autopilot or flight-management modes that have been selected and are standing by, waiting for a specific condition to be met before they automatically engage and take control of a flight parameter.
Plain English
A function that has been set up in advance and will switch itself on when the right moment arrives, rather than working immediately.
Context Anchor
Seen when using cockpit automation such as an autopilot, flight director, navigation system, or altitude capture feature.
Derivation
From the military and mechanical sense of 'armed' — a system made ready to act, but holding until triggered. The same idea as arming a weapon, alarm, or ejection seat: prepared, but not yet active.
Why Pilots Care
Knowing which functions are armed helps the pilot anticipate what the automation will do next and avoid surprises during flight.
Analogy
It is like setting an alarm clock. The alarm is armed once you set it, but it does not ring until the set time arrives.
Intuition Check
Armed does not mean the function is already working. Here it means the function is selected, ready, and waiting to activate when the proper condition occurs.
Example Sentence 1
With the approach mode armed, the autopilot waited until the aircraft intercepted the localizer before automatically capturing the course.
Example Sentence 2
During the approach briefing, the crew confirmed that the approach mode functions were armed for the expected runway.