Fleet commonality

Southwest Airlines has operated a pure Boeing 737 fleet since 1971, operating nearly every variant of the type.

Aviation commonality describes the economic and logistic benefits of operating a standardized fleet of aircraft that share common parts, training requirements, or other characteristics.

Commonality lowers the cost of operating a fleet of aircraft by reducing the quantity and variety of spare parts needed. Pilots and mechanics may also be very quickly "familiarized" to multiple types of aircraft that share common operating and maintenance procedures, reducing downtime.

Commonality policies may be defined in a variety of ways, depending on the operator:

• for civilian aircraft:
  • By model, same generation (e.g. Boeing New Generation 737-700, 737-700ER, 737-700C)
  • By model, different generations (e.g. Boeing New Generation 737-700 and MAX 737-7)
  • By family (e.g. Boeing 737)
  • By manufacturer (e.g. Boeing)
  • By engine (e.g. Rolls-Royce RB211)
  • Any combination of the above

• for military aircraft, the same can be said:
  • By model, same generation (e.g. Lockheed F-16A, F-16B)
  • By model, different generations (e.g. Lockheed F-16A/B, multirole F-16C/D)
  • By family (e.g. Lockheed F-16)