Definition
The standardized 28-day interval on which navigation databases used by airborne avionics (such as GPS receivers and Flight Management Systems) are updated and reissued. Each new cycle reflects current charted information — including waypoints, airways, instrument procedures, frequencies, and airport data — and replaces the previous cycle on a fixed effective date. Operators flying under IFR with database-dependent equipment must ensure the database is current for the dates of intended use.
Plain English
Aviation databases inside the aircraft's navigation equipment get refreshed every 28 days. Each refresh contains the latest official information about routes, waypoints, approaches, and airports. Pilots have to make sure the database in their equipment is up to date before flying.
Context Anchor
Seen when checking the database currency of GPS units, flight management systems, and other aircraft navigation equipment before using them for instrument flying.
Derivation
Revision comes from the idea of reviewing or looking at something again. Cycle means a repeating pattern. In this term, the words point to a reviewed and updated aircraft database that repeats on a fixed 28-day schedule.
Why Pilots Care
Using a database that is not current within this cycle can display outdated or unsafe instrument procedures and obstacle data.
Analogy
It is like a map app that gets a scheduled update, except the aircraft database update follows a fixed aviation calendar and affects approved flight procedures.
Intuition Check
This does not mean the database revises itself while the aircraft is airborne. It means the database used by airborne equipment is issued in scheduled 28-day updates.
Example Sentence 1
Before departing on the IFR cross-country, the pilot verified that the GPS navigation database was within the current 28-day airborne database revision cycle.
Example Sentence 2
A missed update in the 28-day airborne database revision cycle may cause the flight management system to show an obsolete approach procedure.