This figure represent a simplified Airborne Warning and Control System IT systems diagram having 3 isolated networks (red, green and blue). In reality there are many more internal networks with different security levels for utilities, radar systems, navigation, video, external communications VoIP etc. Networks with the same function and same security level are also segmented to improve reliability and security. The set of requirements for equipment that touches these networks is very challenging. System must be secure to avoid leakages between networks and external intrusions. System also must recover in fast and controllable manner from catastrophic events (surviveability, fail-safe). Aircraft systems must be designed to comply with civil and military aviation certification.