Plain English Meaning
Choosing to land somewhere other than where you originally planned, because something has changed and the new airport is the safer or smarter choice.
Full Definition
A change of flight plan to a destination other than the originally intended airport, made in response to a condition that makes continuing to the planned destination unsafe or impractical — such as an inadvertent icing encounter, deteriorating weather, a mechanical issue, or a medical emergency.
Context Anchor
In an inadvertent icing encounter, a pilot may need a flight diversion to leave icing conditions or land at a safer airport.
Derivation
From the Latin divertere, meaning 'to turn aside.' A diversion is literally turning the flight aside from its planned path to a different airport.
Why Pilots Care
A diversion requires recalculating fuel, updating ATC, and ensuring the alternate airport can be reached safely, directly impacting flight safety in icing conditions.
Intuition Check
A flight diversion is not a failure to complete the flight. It is a deliberate change of plan to keep the flight safe.
Example Sentence 1
After picking up unexpected ice in the clouds, the pilot requested a flight diversion to the nearest suitable airport.
Example Sentence 2
In the event of an inadvertent icing encounter, air traffic control may suggest a flight diversion to an alternate with better weather.