What is the minimum crossing altitude (MCA)?

The minimum crossing altitude (MCA) is defined as the lowest altitude at which an aircraft is required to cross specific fixes along a route. This altitude is established by air traffic control and is designed to ensure that the aircraft maintains a safe vertical separation from terrain and obstacles below, especially in mountainous regions or areas with significant elevation changes.

Crossing at or above this altitude ensures that pilots adhere to safe operating procedures while navigating through controlled airspace or transitioning to different flight segments. It plays a crucial role in maintaining safety during the approach and departure phases of flight, allowing for the appropriate vertical clearance even in complex airspace configurations.

The other definitions provided do not accurately capture the unique role of the MCA. For instance, while the altitude for descending and safe navigation away from obstacles are important considerations in aviation, they do not specifically define what the MCA is. Similarly, the concept of a standard altitude for approach does not encompass the specific navigational requirements associated with the minimum crossing altitude.