DGCA Technical General: Windshear & Airframe Contamination Questions
32 exam-style Windshear & Airframe Contamination questions for the DGCA Technical Generalpaper (CPL & ATPL). The first 12 are free below with answers and explanations — sign up free to practise all of them with progress tracking.
- Q1
After an aircraft has been exposed to severe weather:
- Asnow should be removed but smooth ice may be left
- Ball snow and ice should be removed
- Cloose snow may be left but ice must be removed
- Dproviding the contamination is not too thick, it may be left in place
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Correct answer: B. all snow and ice should be removed
All frost, ice and snow must be removed before flight; even a thin, smooth layer roughens the surface enough to severely reduce the maximum lift coefficient and increase the stalling speed, as well as adding weight.
- Q2
Take-off EPR is being delivered by all engines and the take-off is proceeding normally, the undercarriage has just retracted. Which initial indications may be observed when a headwind shears to a downdraught?
- AIndicated Air Speed: constant. Vertical Speed: decreases. Pitch Attitude: decreases.
- BIndicated Air Speed: increases. Vertical Speed: decreases. Pitch Attitude: constant.
- CIndicated Air Speed: decreases. Vertical Speed: constant. Pitch attitude: constant.
- DIndicated Air Speed: decreases. Vertical Speed: decreases. Pitch Attitude: decreases.
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Correct answer: D. Indicated Air Speed: decreases. Vertical Speed: decreases. Pitch Attitude: decreases.
This Explanation is Coming Soon
- Q3
Icing conditions may be encountered in the atmosphere when:
- Arelative humidity is low and temperature rises
- Bpressure is high and humidity falls
- Crelative humidity is high and temperature is low
- Drelative pressure is high and temperature is high
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Correct answer: C. relative humidity is high and temperature is low
Airframe icing needs both moisture and cold, so it is encountered when relative humidity is high and the temperature is low, around or below freezing.
- Q4
Maximum downdrafts in a microburst encounter may be as strong as
- A6,000 ft/min.
- B7,000 ft/min.
- C8,000 ft/min.
- D10,000 ft/min.
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Correct answer: A. 6,000 ft/min.
The downdraft in the core of a microburst can reach about 6,000 feet per minute, a descent rate far beyond the climb capability of most transport aircraft. This figure is the accepted maximum used in windshear training.
- Q5
Which is an effect of ice, snow, or frost formation on an aeroplane?
- AIncreased angle of attack for stalls
- BIncreased stall speed
- CIncreased pitch down tendencies
- DDecreased speed for stalling
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Correct answer: B. Increased stall speed
Ice, snow or frost roughens the wing surface and disrupts the boundary layer, reducing the maximum lift coefficient, so the aircraft stalls at a higher speed and a lower angle of attack.
- Q6
An aircraft that encounters a headwind of 45 knots, within a microburst, may expect a total shear across the micro burst of
- A80 knots.
- B40 knots.
- C90 knots.
- D45 knots.
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Correct answer: C. 90 knots.
Flying through a microburst the aircraft first meets a headwind, then the downdraft core, then an equal tailwind on the far side, so the total shear is twice the initial headwind component. With a 45 knot headwind the total change across the burst is therefore 90 knots.
- Q7
Frost covering the upper surface of an aircraft wing will usually cause:
- Athe aircraft to stall at an angle of attack that is lower than normal
- Bno problems to pilots
- Cdrag factors so large that sufficient speed cannot be obtained for take-off
- Dthe aircraft to stall at an angle of attack that is higher than normal
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Correct answer: A. the aircraft to stall at an angle of attack that is lower than normal
This Explanation is Coming Soon
- Q8
What is the expected duration of an individual micro burst?
- ATwo minutes with maximum winds lasting approximately 1 minute.
- BSeldom longer than 15 minutes from the time the burst strikes the ground until dissipation.
- COne micro burst may continue for as long as 2 to 4 hours.
- DFor as long as 1 hour.
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Correct answer: B. Seldom longer than 15 minutes from the time the burst strikes the ground until dissipation.
An individual microburst seldom lasts longer than about 15 minutes from the moment it strikes the ground until it dissipates, with the most intense winds lasting only a few minutes. Its danger lies in this short life, which makes it hard to detect and report in time.
- Q9
If it is suspected that ice may have formed on the tailplane and longitudinal control difficulties are experienced following flap selection. the prudent action to take would be:
- Aimmediately decrease the flap setting
- Ballow the speed to increase
- Cselect a greater flap deflection because this will increase C L max
- Dreduce the angle of attack
Show answer
Correct answer: A. immediately decrease the flap setting
Extending flap increases the downwash over the tailplane, driving an ice-contaminated tailplane towards its stalling angle. The prudent response to control difficulty after flap selection is therefore to retract the flaps to the previous setting immediately.
- Q10
Which wind-shear condition results in a loss of airspeed?
- ADecreasing headwind or tailwind.
- BIncreasing headwind and decreasing tailwind.
- CDecreasing headwind and increasing tailwind.
- DIncreasing headwind or tailwind.
Show answer
Correct answer: C. Decreasing headwind and increasing tailwind.
Indicated airspeed falls when the air the aircraft is flying in shears so that the relative wind decreases, that is when a headwind decreases or a tailwind increases. An increasing headwind or decreasing tailwind produces the opposite effect, a temporary gain of airspeed.
- Q11
When considering in-flight airframe contamination with frost or ice, which of the following statements is correct?
- ABuild-up can be identified by the ice detection equipment fitted to the aircraft
- BThe pilot can visually identify build-up on the wings, tailplane or flight controls by looking through the flight deck windows; at night by using the ice detection lights.
- CVisual evidence of the accumulation of airframe icing may not exist
- DDue to the high speed of modern aircraft, significant airframe contamination with frost, ice or snow will not occur
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Correct answer: C. Visual evidence of the accumulation of airframe icing may not exist
Frost or ice can build up where the crew cannot see it, and thin clear ice may be invisible from the flight deck, so visual evidence of accumulation may simply not exist; absence of visible contamination is no guarantee the airframe is clean.
- Q12
Which performance characteristics should be recognized during takeoff when encountering a tailwind shear that increases in intensity?
- ALoss of, or diminished climb ability
- BIncreased climb performance immediately after takeoff.
- CDecreased takeoff distance.
- DImproved ability to climb.
Show answer
Correct answer: A. Loss of, or diminished climb ability
A tailwind that strengthens during the climb-out continuously robs the aircraft of indicated airspeed, forcing a lower pitch attitude to maintain flying speed, so climb capability is diminished or lost entirely. It is the classic performance-decreasing shear on take-off.
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