Definition
An airport, runway, or landing site that a pilot identifies in advance as a usable place to land if the planned destination becomes unavailable or if an in-flight problem requires landing sooner than planned. In the context of closed indefinitely airports, it refers to using such a closed field only when no safer alternative exists and the situation justifies the risk.
Plain English
A backup place to land — either because plans changed (diversion) or because something has gone wrong and you need to get on the ground (emergency).
Context Anchor
Seen in instrument procedure discussions about airports that are closed indefinitely and should not be treated as normal planned destinations, but may still be considered only in an unplanned safety situation.
Derivation
‘Diversionary’ comes from the Latin divertere, meaning ‘to turn aside.’ A diversion is a turn away from the original plan. ‘Emergency’ comes from the Latin emergere, ‘to rise up’ — an unexpected situation that suddenly arises and demands action. Together the phrase covers both planned alternates and unplanned, urgent landings.
Why Pilots Care
Ensures continued safe flight and regulatory compliance when a destination becomes permanently unavailable.
Grounding Statement
This term means “not part of the normal plan, but possibly useful if the normal plan becomes unsafe.”
Intuition Check
Do not read “option” as meaning “freely available for normal use.” Here, it means a backup or last-resort choice for a diversion or emergency.
Example Sentence 1
Before crossing the mountains, the pilot identified two diversionary or emergency options along the route in case weather closed in.
Example Sentence 2
Reviewing the diversionary or emergency option before departure allowed quick action when the destination closed.