Definition
An airport, other than the original destination, that a pilot plans to fly to if landing at the intended destination becomes impractical or impossible due to weather, mechanical issues, traffic, or other operational factors. The alternate is selected before or during flight and must meet specific suitability requirements, including adequate weather minimums and sufficient fuel reserves to reach it after attempting the primary destination.
Plain English
A backup airport the pilot can fly to if the planned destination is no longer a safe or workable place to land.
Context Anchor
Seen during flight diversion planning, especially when weather, fuel, aircraft condition, or other changing conditions require a pilot to choose a new place to land.
Derivation
From the Latin alternatus, meaning 'every other' or 'one after another.' In aviation, the alternate is the next-in-line option — the place you go when the first choice is unavailable.
Why Pilots Care
Provides a pre-planned option that maintains fuel reserves and safety margins when conditions at the intended airport change.
Intuition Check
Do not assume an alternate destination always means the formal alternate airport listed on an IFR flight plan. In a flight diversion, it simply means the new place you choose to land instead of the original destination.
Example Sentence 1
With thunderstorms forming over the destination, the pilot diverted to the alternate destination filed on the IFR flight plan.
Example Sentence 2
With the alternate destination only thirty minutes away, the flight maintained the required fuel reserve.