Definition
An airport designated in the flight plan to which an aircraft can divert shortly after takeoff if a return to the departure airport is not possible due to weather below landing minimums or other operational reasons. Required under commercial operating rules when weather at the departure airport is below the authorized landing minimums for that airport.
Plain English
A backup airport listed for use right after takeoff, in case something goes wrong and the aircraft cannot land back at the airport it just left. It is needed when the weather at the departure airport is too poor to allow an immediate return.
Context Anchor
Seen in commercial flight planning and release paperwork, especially when the weather at the departure airport is too low to allow a return landing after takeoff.
Derivation
Alternate comes from a word meaning to take turns or take the place of another. In aviation, an alternate airport is not just another possible airport; it is a planned backup that can take the place of the original airport if needed.
Why Pilots Care
Ensures regulatory compliance and provides a safe option for immediate diversion, reducing risk in marginal departure conditions.
Grounding Statement
Picture departing into low weather: if something goes wrong just after takeoff, the takeoff alternate airport is the nearby landing plan already chosen before the wheels left the runway.
Intuition Check
Do not read this as any airport you might choose after takeoff. In this context, it means a specific planned backup airport that must meet required weather, distance, and suitability rules before departure.
Example Sentence 1
Because the visibility at the departure airport was below landing minimums, the dispatcher listed a takeoff alternate airport thirty miles to the south on the release.
Example Sentence 2
The dispatcher included the takeoff alternate airport in the flight release as required for Part 121 operations.