Smesta

A level maintained during a significant portion of a flight.

That vertical displacement above low level air defence systems, expressed both as height and altitude, at which aircraft can cross the area.

The lowest flight level available for use above the transition altitude.

The level at which activities, battles and engagements are planned and executed to accomplish military objectives assigned to tactical formations and units.

The level at which campaigns and major operations are planned, conducted and sustained to accomplish strategic objectives within theatres or areas of operations.

A surface to which elevations, heights or depths on a map or chart are related.

The arbitrary level from which vertical displacement is measured. The datum for height measurement is the terrain directly below the aircraft or some specified datum; for pressure altitude, the level at which the atmospheric pressure is 29.92 inches of mercury (1013.2 m.bs); and for true altitude, mean sea level.

The level at which a nation or group of nations determines national or multinational security objectives and deploys national, including military, resources to achieve them.