相关题目
（ ） is the vertical distance of a point or level, on or affixed to the surface of the earth, measured from Mean Sea Level.
（ ） is an altitude or flight level maintained during en-route level flight.
（ ） is the vertical distance of a level, a point or an object considered as a point, measured from Mean Sea Level.
（ ） is a control area or portion thereof established in the form of a corridor, the centerline of which is defined by radio navigational aids.
（ ） is navigable airspace between two points which is identifiable.
（ ） is a point on the airport designated as the official airport location.
（ ） is the area of airspace over land or water, extending upward from the surface, within which the ready identification, the location, and the control of aircraft are required in the interest of national security.
（ ） is a number expressing the relative effect for an aircraft on a pavement for a specified standard subgrade category.
（ ） is an area of land or water that is used or intended to be used for the landing and takeoff of aircraft, and includes its buildings and facilities, if any.
（ ） is an aerodrome specified in the flight plan to which a flight may proceed when it becomes inadvisable to land at the aerodrome of intended landing.
