What is the term used for the altitude that assures navigation coverage in mountainous terrain?

The term that refers to the altitude ensuring navigation coverage in mountainous terrain is known as the Minimum Enroute Altitude (MEA). This altitude guarantees that an aircraft remains clear of obstacles and provides the necessary signal coverage from navigational aids during its enroute phase of flight. By maintaining the MEA, pilots can ensure they are flying at a safe level that accounts for the highest terrain or obstacles along the flight path, thus reducing the risk of inadvertent encounters with mountainous features.

In mountainous areas, the MEA not only provides vertical clearance but also incorporates navigational requirements, making it critical for safe navigation. It is especially important in regions where terrain can rise abruptly, as it provides a buffer against both established physical obstacles and ensures the reliable reception of navigation signals.

The other options, while relevant to various aspects of aviation navigational planning and safety, do not specifically address altitude assurances in mountainous terrain. For instance, Minimum Descent Altitude/Height (MDA/H) relates to the lowest altitude for an approach, while Minimum Authorized Altitude (MAA) is more about ensuring compliance with airspace limits without specific focus on terrain. Minimum Off-Route Altitude (MORA) is a different concept that provides minimum altitudes for off-route navigation but