What is an aircraft's minimum equipment list (MEL)?

The minimum equipment list (MEL) is a critical safety document that identifies the equipment and instruments that must be functioning properly for an aircraft to be considered safe to operate. This list is specific to each aircraft and outlines which systems can be inoperative while still allowing for safe flight. The MEL ensures that essential equipment, such as navigation systems, communication systems, and safety equipment, are operational, thus maintaining the safety and airworthiness of the aircraft.

Understanding the MEL is vital for flight crews and maintenance personnel, as it helps to make informed decisions regarding the operational status of an aircraft. It emphasizes that only non-essential systems can be inoperative, thus providing clear guidelines for safe operations. In essence, the MEL acts as a safeguard, ensuring that all critical components necessary for a safe flight are functional, while allowing some flexibility regarding non-essential equipment.