ATPL(A) 032 PerformanceRevision notes and practice questions

032 PerformanceFree sample, 10 questions

1. 1For a multi-engined piston aeroplane, the climb gradient from 50 ft above the take-off reference point up to the cloud base is assumed to be the (1) ______ multiplied by a factor of 0.77. Once the aeroplane has entered cloud and is no longer in VMC, the climb gradient is assumed to be the (2) ______.

   1. (1) OEI climb gradient; (2) OEI climb gradient
   2. (1) all-engine climb gradient; (2) all-engine climb gradient
   3. (1) all-engine climb gradient; (2) OEI climb gradient
   4. (1) OEI climb gradient; (2) all-engine climb gradient
   Show the answer

   Answer C. For multi-engined class B take-off obstacle clearance, the gradient from 50 ft up to the point where visual reference is lost is taken as the all-engine climb gradient factored by 0.77. Once the aeroplane enters cloud and is no longer in VMC, an engine failure is assumed at that point, so from there the one-engine-inoperative climb gradient must be used.

2. 2Two aircraft with the same weight and configuration, at the same altitude, are climbing at the same pitch angle. Assume a standard atmosphere and no compressibility effects. Aircraft A is at Mach 0.75 and aircraft B at Mach 0.73. Which one has the higher rate of climb?

   1. Aircraft A
   2. Aircraft B
   3. Aircraft A below FL 300, thereafter Aircraft B
   4. It cannot be determined without the TAS
   Show the answer

   Answer A. At the same altitude both aircraft have the same local speed of sound, so the one flying at Mach 0.75 has the higher TAS. With the same pitch angle, taken here as the same climb angle, the rate of climb equals TAS multiplied by the sine of the climb angle, so aircraft A climbs faster. The TAS is not needed separately: at a common altitude the Mach numbers already rank the true airspeeds.

3. 3Which statement about the climb gradient is correct? The climb gradient is...

   1. Always equal to the pitch attitude.
   2. Always smaller than the angle of climb.
   3. The same as the angle of climb.
   4. Always larger than the angle of climb.
   Show the answer

   Answer D. The climb gradient is the height gained per 100 units of horizontal distance, in other words the tangent of the climb angle expressed as a percentage. Because tan θ × 100 is always greater than θ in degrees, the gradient figure is larger than the angle: a 3° climb is a 5.2 % gradient. Treating the two as equal confuses a ratio with an angle.

4. 4How does a full-flap approach and landing compare with a zero-flap one? The full-flap approach and landing will have a...

   1. faster approach speed and shorter ground roll distance.
   2. slower approach speed and shorter ground roll distance.
   3. faster approach speed and larger ground roll distance.
   4. slower approach speed and larger ground roll distance.
   Show the answer

   Answer B. Full flap lowers the stalling speed, so the approach and touchdown are flown at a lower speed, and the extra drag helps the deceleration. With less kinetic energy to dissipate, the ground roll is shorter than with zero flap. A zero-flap landing means a faster approach and a longer ground roll.

5. 5For performance class A aeroplanes, V2MIN may not be less than which of the following?

   1. 1.08 VSR for turbojets without provision for obtaining a significant reduction in the one-engine-inoperative power-on stalling speed.
   2. 1.08 VSR for turboprops with 2 engines.
   3. 1.1 VMC as mentioned in the CS-25
   4. 1.13 VSR for turboprops with more than 3 engines.
   Show the answer

   Answer C. CS-25 requires V2MIN to be at least 1.1 VMC, and also at least 1.13 VSR for two- and three-engine turboprops and for turbojets without a significant reduction in the one-engine-inoperative power-on stall speed. The 1.08 VSR factor applies only to turboprops with more than three engines and to turbojets that do have such a reduction. Each wrong option swaps the 1.08 and 1.13 factors between these groups.

6. 6During pre-flight planning for a Commercial Air Transport flight, the pilot has worked out several performance-limited landing masses. From the limits below, determine the maximum performance-limited landing mass that meets the operational requirements.
   Approach climb limit mass: 32 250 lb
   Landing climb limit mass: 38 300 lb
   Field length limit mass: 34 500 lb
   Structural limit landing mass: 39 300 lb

   1. 38 300 lb
   2. 39 300 lb
   3. 32 250 lb
   4. 34 500 lb
   Show the answer

   Answer C. The performance-limited landing mass is the lowest of all the limits that apply: approach climb, landing climb, field length and structural. Here the approach climb limit of 32 250 lb is the lowest, so it is the maximum landing mass that complies with every requirement. Choosing the structural or field length limit ignores the fact that all the limits must be met at the same time.

7. 7What can be done to reduce the problems caused by asymmetric thrust on a twin-engined propeller aeroplane?

   1. Use counter-rotating propellers.
   2. Place the engines a greater distance from the aircraft's centre line.
   3. Place the engines further forwards on the wings.
   4. Use propellers with no more than 3 blades.
   Show the answer

   Answer A. With both propellers turning the same way, asymmetric blade effect (P-factor) makes one engine critical because its thrust line sits closer to the centreline. Counter-rotating propellers make the thrust lines symmetrical, so there is no critical engine and the yawing moment after a failure is the same whichever engine fails. Moving the engines further outboard would lengthen the moment arm and make asymmetry worse, and blade count or fore-aft position does not solve it.

8. 8All other factors remaining constant, how does retracting the gear, flaps and slats affect the Vx and Vy of an aeroplane?

   1. Vx increases and Vy decreases.
   2. Vx decreases and Vy increases.
   3. Both increase.
   4. Both decrease.
   Show the answer

   Answer C. Gear, flaps and slats mainly add parasite drag, which raises the drag and power-required curves and moves their minima to a lower speed. VX is where the excess thrust is greatest and VY where the excess power is greatest, so both are lower with the aeroplane dirty. Retracting them does the reverse: VX and VY both increase, and so do the climb angle and rate. The options where one speed rises and the other falls ignore that both curves shift the same way.

9. 9While flying at the speed for the minimum glide angle, which factor will increase the distance covered over the ground during a glide?

   1. Increase of aircraft mass.
   2. Headwind.
   3. Tailwind.
   4. Decrease of aircraft mass.
   Show the answer

   Answer C. At the best glide speed the still-air glide distance depends only on the lift/drag ratio, so mass changes the speed at which the aeroplane glides but not how far it goes through the air. A tailwind adds to the ground speed throughout the descent, so the same air distance becomes a longer ground distance. A headwind has the opposite effect.

10. 10What is the VREF of a class B single-engine piston aeroplane with a maximum take-off mass of 1633 kg, given these stall speeds?
    VS0: 60 kt
    VS1: 63 kt
    VS: 68 kt

    1. 82 kt
    2. 88 kt
    3. 76 kt
    4. 78 kt
    Show the answer

    Answer D. VREF for a class B aeroplane must be at least 1.3 VS0, the stall speed in the landing configuration. Here 1.3 × 60 = 78 kt. Applying the factor to VS1 (82 kt) or to VS (88 kt) uses the wrong configuration.