Headset
noun headphones with a microphone attached, used for RT communications o Headsets are usually used in preference to hand-held microphones.
Head-up display noun a cockpit system where data from flight instruments is projected onto a screen or the windscreen so that the pilot can see it without having to look down.
Abbreviation HUD
headwind
noun a wind which is blowing in the opposite direction to the direction of movement or flight. Compare tailwind (note: The word is also written head wind.)
headwind component
noun one of the three possible components of a wind, the other two being crosswind and tailwind heap
noun a group of things piled or thrown one on top of another heap cloud
noun same as cumulus cloud
heat
noun warmth, being hot o The heat generated by combustion is considerable. ■ verb to make warm or warmer o The air leaving the turbo-charger is very warm and can be used to heat the cabin.
heater
noun a device for heating Pitot heads contain heater elements to prevent icing.
heating
noun the process of making something warmer o the heating action of the sun i kinetic
heavier-than-air
adjective weighing more than the air it displaces, and so needing power to fly
heavy
adjective having a lot of weight □ a heavy load a load of great weight □ heavy rain rain which is dense and distributes a lot of water over the surface of the Earh in a relatively short time
heavy-duty
adjective referring to something designed for hard wear or use o a heavy-duty battery o Longerons are heavy-duty steel members.
heavy landing
„ noun a routine landing in which the aircraft makes contact with the surface with more force than usual, thereby possibly causing damage to the undercarriage o The pilot reported a heavy landing. hedgehop „ verb to fly at 
very low height above the ground height /halt/ noun the vertical distance of a point, level or object measured from a particular point, e.g. sea level o Pressure decreases with increasing height. □ height of the aircraft the vertical distance, measured in feet, of the aircraft above the surface of the earth
held
hold
heli
noun a rotary-wing aircraft
heliborne
‘ adjective trans ported by helicopter
helicopter
noun an air craft with one or more rotors rotating around vertical axes which provide lift and control o Helicopter operations are carried out at the airport.
helicopter rotor
noun two or more rotating blades, known as the main rotor, which provide lift and thrust for a helicopter;
helideck
noun a deck on something such as a ship or offshore oil platform that is used as a landing area for helicopters
heliograph
noun an instrument with a mirror to send messages by reflecting the sun o Heliographs enable reflected sunlight to be directed to a ship or aircraft in periods of direct sunlight.
helipad
noun an area where helicopters take off and land
heliport
noun an airport designed for helicopters
helistop
noun a place where helicopters can take off and land, but usually one that does not have the support facilities found at a heliport
helo
noun 1. a rotary-winged aircraft 2. same as heliport
hemisphere
noun half a sphere
Hertz
noun the SI unit of frequency, defined as the number of cycles per second of time.
Abbreviation Hz HF abbreviation high frequency high
adjective 1. having great vertical distance o a high mountain 2. great, large, a lot □ high engine rpm fast engine speed □ high pressure a lot of pressure □ high reliability good reliability □ high speed a fast speed □ high temperature a hot temperature ■ noun an area of high atmospheric pressure o There is a high over the British Isles.
high frequency
high frequency band
noun a radio communications range of frequencies between 3-30 MHz.
Abbreviation HF
high-performance
adjective a system which provides better-than-usual output o an engine with a high performance o Some high-performance engines have coolant and oil system thermostats which aid warming-up.
high performance aircraft
noun an aircraft capable of flying faster, higher or with more manoeuvrability than normal aircraft
hijack
verb to take over control of an aircraft by one or several unauthorised person or persons with the intention of forcing the crew to fly it to a different destination o The airliner was hijacked on its way to Paris. hijacker
noun a person who hijacks an aircraft or other vehicle
hijacking
noun the act of taking over control of an aircraft by one or several unauthorised person or persons with the intention of forcing the crew to fly it to a different destination o The crew must be alert at all times to the possibility of hijacking, bombs and stowaways.
hill
noun an easily-seen, natural elevation, smaller than a mountain o Slopes on the side of a hill or mountain facing away from the sun receive less intense radiation. o Hill shading is produced by assuming that bright light is shining across the chart sheet so that shadows are cast by the high ground.
hinder
verb to make it difficult for something to happen o Free flow of fuel may be hindered by a blockage in the fuel line. o Her illness hindered his progress on the course.
hinge
noun a device which allows a door, flap or lid to open and close on a stationary frame o Flying control hinges should be inspected before flight. ■ verb to move against a stationary frame o Access to the engine compartment is normally via hinged cowling panels.
HIRF abbreviation high-intensity radiated fields
HMR abbreviation helicopter main route
hoar
hoar frost noun a frozen dew which forms on outside surfaces when the temperature falls below freezing point o Rapid descent from cold altitudes into warm moist air may produce hoar frost on the aircraft.
hold
‘ noun an area or compartment within the aircraft for carrying freight o Carry-on baggage is limited by regulations as to size and weight and items in excess of this should be stowed in the luggage hold. ■ verb 1. to keep and prevent from moving o The function of the autopilot system is to hold the aircraft on a desired flight path by means of gyroscopes and/or accelerometers. o If the operating pressure falls or fails, a mechanical lock holds the reverser in the forward thrust position. 2. to keep an aircraft in a particular position on the ground or in the air while waiting for further clearance from air traffic control o It is normal practice for ATC to hold taxiing aircraft well clear of the glide path and localizer antenna when visibility is poor. 3. to have and keep in the hand o Hold the microphone in your right hand. □ handheld possible to hold in the hand o Nowadays, headsets are usually used in preference to hand-held microphones. 4. to have (note: holding – held) □ he holds an IMC rating he has an IMC rating
holder
noun 1. a device for holding something o a holder for a fire extinguisher 2. a person who has a particular title or qualification o a holder of two awards for distinguished service
holding fuel
noun extra fuel carried by an aircraft to allow for time spent in the hold waiting for air traffic control clearance holding pattern noun a racetrack-shaped flight pattern with two parallel sides and two turns, flown usually while an aircraft is waiting for clearance to land
holding point
noun 1. a particular location, in the air or on the ground where aircraft spend time, waiting for further clearance from air traffic control 2. a place, often designated Alpha, Bravo, Charlie, etc., where aircraft wait before entering the runway, as instructed by air traffic control
holding stack
an area of airspace where planes are instructed to wait before landing if there are delays (note: Aircraft circle and descend according to the controller’s instructions until they are released from the lowest height in the stack for their final approach to the airport.)
hollow
adjective having a space within, not solid o a hollow drive shaft Opposite solid home
noun the home airfield □ home airfield the airfield which one returns to after a two-leg flight
homeward
adjective going towards home o homeward journey ■ adverb □ homeward bound heading towards home
homewards
adverb towards home o They were heading homewards when the accident happened.
homing
noun a flight towards or away from a radio station while using direction finding equipment o Where an RBI is fitted, homing to an NDB can be made by initially turning the aircraft until the relative bearing is zero.
homogeneous
adjective of the same kind o If the air over a large region were homogeneous, there would be no horizontal differences in surface temperature. o The atmosphere is not homogeneous — pressure, temperature and humidity can all change with height.
hop
noun a flight or section of a flight in an aircraft (informal)
horizon
noun the line where the sky and the ground appear to join □ visual horizon a horizon which can be seen
horizontal
adjective parallel to the horizon, or at right angles to the vertical o The horizontal motion of air is known as wind.
horizontal axis
noun a horizontal reference line of a graph o The plot shows the effect of airspeed on lift with airspeed shown on the horizontal axis and lift on the vertical axis.
horizontal situation indicator
noun a cockpit instrument which gives the pilot information about the direction of the aircraft’s flight path o On the aircraft, the horizontal situation indicator is located on the instrument panel below the attitude indicator. Abbreviation HSI
comment: The horizontal situation indicator combines the function of the heading indicator and a VOR/ILS display.
horizontalstabiliser
noun a tailplane o The horizontal stabiliser provides stability about the lateral axis of the aircraft.
horn
‘ noun a device for projecting sound □ warning horn device which emits a loud warning noise
horn balance
noun part of a control surface forward of the hinge line which reduces the force needed by the pilot to move the surface
horsepower
noun the accepted unit for measuring the rate of doing work o Horsepower is defined as 33,000foot-pounds of work done in one minute.
Abbreviation h.p., HP hose
noun a long, flexible pipe usually made of fabric, plastic or rubber for pumping gases or liquids □ refuelling hose a flexible pipe used to pump fuel from the bowser to the aircraft
hot
adjective very warm, having a high temperature o hot weather □ hot air air introduced to melt ice forming in the carburettor in a piston engine aircraft
hour
noun 1. a period of time which lasts sixty minutes o It’s a three-hour flight to Greece from London. 2. a method of indicating time o Flight BA 321 landed at Heathrow at 10.30 hours.
house
/ verb to contain or accommodate o The areas between the ribs in the wings are utilised to house fuel tanks. o The wing tips house the navigation lights.
housing
noun a compartment or container o The crankcase is the housing that encloses the various mechanical parts surrounding the crankshaft. □ engine housing engine compartment
hover
verb to remain stationary, relative to the earth, while in the air ■ noun a period of stationary flight o During a hover, helicopter pilots must be able to coordinate movements of both hands and feet.
hovercraft
noun a vehicle that can travel over land and water supported on a cushion of air that is produced by a powerful engine that blows air downwards. Also called air cushion vehicle, ground effect machine
however
adverb but o The wind was gusty, however the landing was good. o The incident was serious, however she escaped with only a warning.
hrs abbreviation hours
HSI abbreviation horizontal situation indicator
hub
noun a major airport where international or long-distance flights take off and land
hub airport
noun same as hub
HUD abbreviation head-up display
human factors
noun the study of the way in which humans handle, and react to, things in their environment. It is used in aviation to develop safer systems and procedures. (note: Human factors is followed by a verb in the singular.)
humid _
adjective containing a lot of water vapour □ humid weather weather which, although warm, feels damp and uncomfortable
humidity
noun a measurement of how much water vapour is contained in the air □ the humidity is high there is a lot of moisture or water vapour in the air
hydraulic
adjective referring to any system or device which uses fluids such as oil to transmit a force from one place to another using pipes o a hydraulic pump
hydraulic fluid
noun thin oil used in hydraulic braking systems, etc.
hydraulic pressure
noun the pressure exerted by hydraulic fluid
hydraulic tubing
noun system of tubes or thin pipes connecting the main components of a hydraulic system hydro-
prefix water o a hydro-mechanical governor hygrometer
noun an instrument used for the measurement of humidity o The most common type of hygrometer is the wet and dry bulb thermometer arrangement.
hypoxia
‘ noun a medical condition in which not enough oxygen is supplied to the body o The symptoms of hypoxia are sometimes difficult to detect.
comment: Cabin pressurisation or oxygen equipment is usually required for flying at altitudes at or above about 10,000 ft (3,048 m).
Hz abbreviation Hertz
IAS
abbreviation indicated airspeed
IATA abbreviation International Air Transport Association I-beam
‘ a large bar of metal or some other strong substance with a cross-section shaped like the letter ‘I’ ICAO
‘ abbreviation International Civil Aviation Organization ice
noun frozen water
Ice crystal
noun a type of precipitation composed of crystals in the form of needles, plates or columns
