Definition
The release of air or gas from an inflatable component such as a tire, strut, life raft, life vest, or de-icer boot, causing it to lose pressure and collapse from its inflated shape.
Plain English
Letting the air out of something so it goes flat or slack.
Context Anchor
Seen during preflight inspections, tire servicing, and checks of any aircraft item that must stay inflated.
Derivation
From the Latin 'deflare', meaning 'to blow away'. The prefix 'de-' means 'away from' or 'down', and 'flare' means 'to blow'. So deflation literally means 'blowing the air out'.
Why Pilots Care
Correct deflation prevents tire damage, ensures proper operating pressures, and avoids handling problems or blowouts on takeoff or landing.
Intuition Check
Deflation does not mean a decrease in prices here. In aviation use, it means air or gas pressure is leaving an inflated aircraft part.
Example Sentence 1
The pilot noticed partial deflation of the nose tire during preflight and called maintenance before the flight.
Example Sentence 2
Maintenance required deflation of the main tires to the placarded pressure before the aircraft was returned to service.