It comprises all the technologies related with aircraft electronic equipments (avionics including integration, cockpit, flight management, sensors, communications, etc…), optronics, health and usage monitoring, smart maintenance and aircraft security as well as the technologies for electrical and hydraulic power generation and distribution, fuel systems and landing gear and braking systems. It also includes different service systems (passenger and freight, lighting, environmental control,
water and waste and fire protection ones).

(Source: ACARE Area 4 & PAE own definition)