Plain English Meaning
A short mental check a pilot runs on themselves before flying, to make sure they are healthy, clear-headed, and rested enough to fly safely. If any of the six items is a problem, the pilot doesn't go.
Full Definition
A personal preflight self-assessment used by pilots to evaluate their fitness to fly. The pilot checks themselves against six factors -- Illness, Medication, Stress, Alcohol, Fatigue, and Emotion -- and only flies if none of them are impairing their ability to operate the aircraft safely.
Context Anchor
Used during preflight planning and in the “Pilot” part of the PAVE checklist to judge the pilot’s own readiness before a flight.
Derivation
IMSAFE is a memory aid built from the first letters of the six items it covers. It is designed to be easy to recall in the cockpit or at the planning desk, where a longer checklist might be skipped.
Why Pilots Care
Helps prevent accidents caused by pilot impairment that could affect judgment or aircraft control.
Grounding Statement
The IMSAFE checklist is a quick pause before flight to check whether the pilot is personally fit to act as pilot in command.
Intuition Check
Do not treat “IMSAFE” as a guarantee that everything is safe. It is a reminder to honestly check your own condition before deciding to fly.
Example Sentence 1
Before her early morning flight, she ran through the IMSAFE checklist and decided to delay departure because she had only slept four hours.
Example Sentence 2
Even on short flights, instructors remind students to run the IMSAFE checklist first.