Fleet commonality

In aviation, fleet commonality is the economic and logistic benefits of operating a standardized fleet of aircraft that share common parts, training requirements, or other characteristics. Commonality policies may be defined in a variety of ways, depending on the operator: for civilian aircraft: By model, same generation (e.g. Boeing "Next Generation" 737-700, 737-800, and 737-900) By model, different generations (e.g. Boeing's "Next Generation" 737-700 and 737 MAX-7) By family (e.g. Boeing 737) Between families (e.g. deck, between Boeing 767-400ER, 777 and 737 NG) 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 By model, different generations (e.g. General Dynamics F-16A/B, multirole F-16C/D) By family (e.g. General Dynamics F-16) Commonality can also be seen in engines : By family, same generation (e.g. RR Trent, GE T700) By family, different generations (e.g. CFM 56-2, -3, -5, -7 ) Between aircraft (Pratt & Whitney's F100 with the F-15 and F-16 fleet) Airbus and Boeing have commonality in their products within and across families. The A330 and A340 share many common features. The same cockpit is shared between the A330 and A340, however the A340 controls four engines instead of two on the A330. The A330 and A340 share the same wings, nose, tail and horizontal stabilizers. The A340 features an extra bogie of landing gears under the belly to support extra weight. The A330-300 and A340-300 share the same fuselage and wings, however with the A340-300 featuring an extra bogie of landing gears under the belly, and powered by four engines instead of two. The 767-400ER shares common features with the 757/767 family of airplanes, including a common pilot type rating between the 757 and 767. This allows any pilot trained to fly one model to be qualified to fly the other model with minimal additional instruction.