empennage (airplane structure). The tail section of an airplane. The empennage stabilizes the airplane in flight and causes it to rotate about its vertical and lateral axes.
An inverted cruciform empennage consists of a fixed vertical fin with a movable rudder attached to its trailing edge, and a fixed horizontal stabilizer with a movable elevator hinged to its trailing edge on both sides of the fuselage.
Another type of empennage, the V-tail, has only two fixed and two movable surfaces, arranged in the shape of the letter V. These two surfaces stabilize the airplane and rotate it about its two axes in the same way as the three fixed and three movable surfaces.
empty weight (aircraft specification). The weight of the airframe, engines, and all items of operating equipment that have fixed locations and are permanently installed in the aircraft. Empty weight includes optional and special equipment, fixed ballast, full reservoirs of hydraulic fluid, engine lubricating oil, and the unusable fuel, but does not include occupants, baggage, or cargo.
empty-weight center of gravity (aircraft specification). The center of gravity of an aircraft when it contains only the items specified in aircraft empty weight.
empty-weight center of gravity range (aircraft specifications). The distance between the allowable forward and aft empty-weight CG limits. When EWCG limits are given for an aircraft, and the empty-weight CG falls within these limits, it is not possible to legally load the aircraft so that its operational CG will fall outside its operational CG limits.
EMSAW (enroute minimum safe altitude warning). A function of the NAS Stage A enroute computer. This function aids the controller by alerting him when a tracked aircraft is below, or is predicted to go below, a predetermined minimum IFR altitude.