H Hotel

hand-off - An action taken to transfer the radar identification of an aircraft from one controller to another if the aircraft will enter the receiving controller's airspace, as well as transferring radio communications with the aircraft.

hangar - A shelter used to house or repair an aircraft.

heading - The direction in which the longitudinal axis of the airplane points with respect to true or magnetic north. Heading is equal to course plus or minus any wind correction angle.

heavies - See heavy aircraft.

heavy aircraft - A class of aircraft capable of takeoff weights of 300,000 pounds or more whether or not they are operating at this weight during a particular phase of flight.

hecto pascals - A unit of stress or pressure equal to one newton per square meter times one hundred

heliport - An area of land, water, or structure used or intended to be used for the landing and takeoff of helicopters and includes its buildings and facilities if any.

hemisphere - Either the northern or southern half of the Earth as divided by the equator or the eastern or western half as divided by the meridian.

homing - The procedure of using the direction-finding equipment of one radio station with the emission of another radio station, where at least one of the stations is mobile, and whereby the mobile station proceeds continuously towards the other station.

horizontal stabilizer - The horizontal part of the tail. The horizontal stabilizer helps to increase the stability of the aircraft. It is also known as a tailplane.

Hotel - Designator for the letter "H" in the International Phonetic Alphabet.

hub - An airline's base of operations. An airline's hub is at an airport that houses a large number of its aircraft each night and is the origin of a large number of the airline's connecting flights.

hub-and-spoke system - A system established by the major airlines routing flights through their hub(s). This eases maintenance of their fleet, but compromises safety.

human factors - The interaction between people and machine or the interaction among people that adds the real-time element to any simulated operation.

hypersonic - Velocity greater than five times the speed of sound.

hypothesis - A prediction which needs to be tested to tell if it is correct. An engineer can offer the hypothesis that a particular wing shape will not create enough lift to enable an airplane to fly. His or her hypothesis must then be tested using one or more of the Tools of Aeronautics to determine if it is correct.

hypoxia - An insufficient supply of oxygen in the bloodstream that results in dizziness, unconsciousness and ultimately death.