Depositnoun a layer of collected matter on a surface o A deposit of ice crystals causes the aircraft surfaces to change their aerodynamic characteristics. o Wheel brakes should be inspected for snow or ice deposits.
depressionnoun 1. an area of low atmospheric pressure o In the northern hemisphere, the wind blows anticlockwise round a depression and clockwise round an anticyclone and vice versa in the southern hemisphere. □ deep depression area of very low relative atmospheric pressure 2. a lower area on a surface, which is often difficult to see o A depression on the wing surface must be investigated in case it is an indication of more serious structural damage.
descent‘ noun a planned loss of altitude o The descent from cruise altitude took 40 minutes. □ in the descent during planned loss of altitude, usually in preparation for landing’… a search of radar recordings showed that a DC-10 had tracked within a few hundred metres of the house while passing 9,500 feet in the descent to Gatwick’ [Pilot]
describeverb 1. to give the particular features of something □ to describe what happened put into words exactly what happened 2. to draw a geometric figure or to move in a line that forms a geometric figure o The definition of a year is the time taken for a planet to describe one orbit around the sun. □ to describe an arc to draw or move in an arc
descriptionnoun 1.the act of giving the particular features of something o a detailed description of world climate 2. the drawing or making of a geometric figure □ the description of a triangle the drawing of a triangle
designnoun a plan or drawing of something before it is made o The design and testing of aircraft are important stages in the development programme. ■ verb to draw plans using accurate information in preparation for constructing something □ to design an aircraft to have the idea, make drawings, calculate data, etc., with the intention of producing an aircraft
designatornoun a group of letters and/or numbers that identify something designernoun a person who has the idea for, and makes plans to produce, something o Rutan is a designer of unusual-looking aircraft. test-pilot’s tip for a safe first flight -take the designer with you’ [Flight International 9-15 Oct. 1996]
desirableadjective preferred or wanted o Equalisation of the air pressure across the eardrum is more difficult to achieve during descents than ascents, and a minimum rate of pressure change is desirable.
despite1 preposition in spite of o Many beacons and aids which are provided for low operations are left out to keep the chart clear — despite this, the charts still look very difficult to understand. □ despite the weather, we took off although the weather was bad, we took off
DEST abbreviation destination
destroy/ verb to damage so much as to make useless o The aircraft was destroyed in the accident. destructionnoun an act or instance of making completely useless by breaking o By testing selected parts to destruction, a safe life can be assessed for all structures and components.
detachverb to remove a part from something, or to be removed o A fuselage panel became detached and had to be replaced. o The parachute flare is a device which is fired to a height of 1,200ft where a red flare and parachute detach.
detachableadjective referring to something which can be unfixed and removed detachable wheel spatsplural noun streamlined coverings for the wheels of light aircraft which can be taken off to allow inspection and repairs of tyres detailnoun the important and less important facts about something o The amount of detail which appears on a topographical chart depends upon the scale.
detection‘ noun the discovery of the presence of something detector‘ noun a device for discovering the existence of something □ ice detector a device for detecting the presence of ice on the airframe o When ice forms on the vibrating rod ice detector head, the probe frequency decreases.
deteriorateverb to become or make bad or worse o The electrolyte in the cells of a nickel-cadmium battery does not chemically react with the plates and so the plates do not deteriorate. □ deteriorating weather worsening weather
determinationnoun 1. the act of finding out by calculation o Structure design for a given safe life has led to the determination of the minimum number of flying hours which should pass before major failure occurs. 2. the strength of mind to do what is required o Determination was a major factor in the trainee passing his exams.
determineverb 1. to find out by calculation o To determine the average age, divide the total number of years by the number of people. o When we wish to fly from one place to another, it is first necessary to determine the direction of the destination from the departure point. 2. to set or to fix precisely o On a large transport aircraft, the safety of hundreds of passengers is involved, and regulations determine the minimum crew that must be carried. detonationnoun a sudden, explosive burning of the air/fuel mixture o Prior to the accident, engine detonation could be heard by people on the ground.
comment: Detonation imposes excessive loads on the pistons and other engine components, possibly causing engine damage and resulting in engine failure.
developverb 1. to come into being Carburettor icing may develop in any type of carburettor in relatively warm air temperatures. o Vertical motion and therefore turbulence suggest that thunderstorms may develop. 2. to get bigger, to grow and change o During the day, light breezes may develop into strong winds.
developmentnoun1. something new, made as an improvement on something older o Satellite navigation aids for light aircraft are a recent development. 2. growth and change o To study weather and its development, the meteorologist has to be aware of the horizontal changes in atmospheric pressure both in space and time.
deviation‘ noun 1. the process of moving away from the normal position or path o On final approach, any deviation from the extended centreline of the runway should be corrected immediately. 2. a magnetic compass error in a particular aircraft caused by magnetic influences in the structure and equipment of the aircraft itself o Deviation is not a constant value but varies from one aircraft to another.
comment: Weather reports usually include the air temperature and dew point temperature. When the difference between temperature and dew point is small, there is a strong possibility of fog, clouds, or precipitation.
DF abbreviation direction finding DFDR abbreviation digital flight data recorder
DFR abbreviation departure flow regulation
DFTI abbreviation Distance from touchdown indicator DH abbreviation decision height DI abbreviation direction indicator
diagonaladjective 1.joining two opposite corners of a rectangle 2. sloping halfway between the vertical and horizontal o Early aircraft were of the wire braced type of construction, the wire being superseded by tubular diagonal struts. ■ noun a line joining two opposite corners of a rectangle
diagrammaticadjective referring to something which is shown as a drawing of a system or structure □ diagrammatic format in the form of a diagram dialnoun the face of an instrument showing a scale A cup anemometer is connected to an instrument with a dial showing wind speed in knots.
diameter‘ noun the distance from one side of a circle to the other, passing through the centre □ equatorial diameter the distance from the equator, through the centre of the Earth to the equator on the opposite side of the globe diaphragmnoun a thin sheet of material used to separate parts or chambers o Some switches are operated by a diaphragm which flexes under fluid or air pressure.
differverb to be unlike o Track and heading differ by the amount of drift. o Because the chart time and the departure/arrival times differ, it is necessary to consider the movement of any weather system which might affect the route.
differentialadjective referring to things which react differently when measured against a norm or standard □ differential heating of the atmosphere the heating of the atmosphere to varying temperatures depending on the relative warmth of the land at the equator and the poles differential expansion switch
diffuseadjective spread out in every direction o Glare caused by diffuse reflection of sunlight from the top of a layer of fog or haze can seriously reduce air-to-ground visibility. ■ verb to spread out in every direction o Light diffuses as it passes through fog.
dimensionnoun a measurable distance such as height, length, etc., or a measurement of height, length, etc. o Variations of atmospheric pressure produce changes in the dimension of the capsule chamber.
diminishverb to decrease or to reduce in size or importance o Friction is greatest near the ground and diminishes with height. o At higher altitudes, ground objects are less easily seen because of diminished size.
directadjective 1. in a straight line; by the shortest route o a direct flight 2. complete o the direct opposite ■ verb to guide or control the movement of something o Clamshell doors are hydraulically or pneumatically opened, and direct the exhaust gases forwards to produce reverse thrust.
direct currentnoun an electric current flowing in one direction only o An electric starter is usually a direct current electric motor coupled to the engine, which automatically disengages after the engine starts. Abbreviation DC
directionaladjective referring to the course taken by somebody or something directional gyronoun a gyroscopic instrument which indicates direction but does not have a north-seeking magnet o The directional gyro should be set to correspond with the magnetic compass. i> heading indicator directional radar beamnoun a signal from a directional beacon enabling the pilot to determine a bearing from the beacon with a communications receiver
directive1 adjective refer ring to the ability of a device to send or receive signals in straight lines o The antenna is highly directive in transmission and reception. ■ noun general or detailed instructions from management to staff to guide them in their work o According to the management directive, all late arrivals should be logged.
Directornoun 1. a device with a central controlling function o EFIS is a highly sophisticated type of flight director system. 2. a person who is a member of the board that controls the activities of a company o managing director