Definition
A symbol shown on an instrument approach chart indicating that the airport may not be filed as an alternate destination on an IFR flight plan, typically because the airport lacks the weather reporting, navigation infrastructure, or approach minimums required to qualify it as an alternate.
Plain English
A note on the approach chart that tells you this airport cannot be listed as your backup airport on an IFR flight plan.
Context Anchor
Seen on instrument approach procedure charts and in IFR alternate planning.
Derivation
The letter 'A' refers to alternate, and 'N/A' is the common shorthand for 'not authorized' (sometimes read as 'not applicable'). The triangle symbol with the 'A' inside is the chart convention; 'N/A' next to it tells the pilot the alternate option is closed off for that airport.
Why Pilots Care
FAR 91.169 requires an alternate airport to be filed when weather conditions warrant. If a pilot picks an airport marked A N/A as their alternate, the flight plan does not meet legal requirements, and the flight cannot launch under IFR until a qualifying alternate is filed.
Intuition Check
Do not read N/A here as just not applicable or unimportant. In this chart context, it means the procedure is not authorized for alternate-airport planning.
Example Sentence 1
When planning the IFR flight, the pilot noticed A N/A on the approach plate and had to choose a different alternate.
Example Sentence 2
Pilots scanning the requirements column noted A N/A and proceeded without planning an alternate.