Definition
A three-letter day-of-week code used in NOTAMs, flight planning documents, and aeronautical publications to indicate Sunday.
Plain English
SUN is short for Sunday when written in flight planning notes and notices to pilots.
Context Anchor
Seen in airport notices, runway or service schedules, and other time-based aviation information.
Why Pilots Care
Some airport services, control towers, and restricted areas operate only on certain days. Reading 'SUN' correctly tells the pilot whether a runway, fuel service, or airspace restriction applies on the day of the flight.
Intuition Check
SUN does not mean the sun in the sky here. In this aviation schedule context, it means Sunday.
Example Sentence 1
The NOTAM stated the tower was closed SUN, so the pilot planned to use the CTAF frequency for arrival.
Example Sentence 2
Check the schedule to confirm the briefing is available every SUN morning.