MIL-HDBK-268, MILITARY HANDBOOK: SURVIVABILITY ENHANCEMENT, AIRCRAFT CONVENTIONAL WEAPON THREATS, DESIGN AND EVALUATION GUIDELINES (5 AUG 1982)., This handbook is a reference document providing uniform design and evaluation guidelines for the survivability enhancement of aircraft Mission-Essential Weapon Systems (MEWS) for the Naval Air Systems Command, to ensure that effective combat operations are achieved when operating in a conventional weapon threat environment. The design guidelines encompass signature suppression (or its control) and vulnerability reduction. Those elements and design activities that are related to survivability enhancement, but are derived from the degradation of threat subsystem functions (e.g., electronic warfare) or from the ways that the aircraft can be utilized in a hostile environment (e.g., tactics) are not included. The evaluation guidelines, for the purpose of achieving systematic quantification and evaluation of combat survivability, include definition of mission scenario and associated threat environment, vulnerability to threat damage mechanisms, encounter survivability, and survivability enhancement trade-offs.