Plain English Meaning

An airport you have picked out as a backup place to land if something goes wrong and you can't make it to where you were planning to go.

Full Definition

An airport identified before or during flight as a suitable landing site if the planned destination becomes unreachable due to an in-flight emergency, system failure, weather deterioration, or other unforeseen condition. The airport is selected based on factors such as runway length, available approaches, fuel and maintenance services, weather, and proximity to the route of flight.

Context Anchor

Seen in instrument procedure and chart discussions when planning what options exist if the flight cannot safely as planned.