The zoning of large aircraft is specified by the Airline for America (A4A) in the ATA-100 Specification. These large areas or major zones are further divided into sequentially numbered zones and subzones. A zone is identified by one of three indicators, depending upon whether it is a major zone, major sub-zone, or simply a zone. Major zones are identified by three-digit numbers as follows:
Aircraft Major Zones


Major Zone | Area |
---|---|
100 | Lower half of the fuselage to the rear pressure bulkhead |
200 | Upper half of the fuselage to the rear pressure bulkhead |
300 | Empennage, including fuselage aft of the rear pressure bulkhead |
400 | Power plants and struts or pylons |
500 | Left-wing |
600 | Right-wing |
700 | Landing gear and landing gear doors |
800 | Doors |
900 | Reserved for uncommon differences between aircraft types not covered by standard series numbers |