I85PREP
⌘ K
ATPL Performance study materials
ATPL Performance study resources

ATPL Performance (Australian CASA Pilot Theory Exams) practice questions

One question at a time. Build your ATPL Performance understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Take-off performance

On a take-off performance chart, the take-off distance required is defined as the distance from the start of the take-off roll to the point where the aircraft:

  1. lifts off and the wheels leave the ground
  2. reaches 50 ft above the runway with all engines operating Correct answer.
  3. reaches 35 ft above the runway with one engine inoperative
  4. achieves V1 with all engines operating

Explanation

Take-off distance required (TODR) is measured to the point where the aeroplane has climbed to 50 ft above the take-off surface with all engines operating, at the scheduled take-off safety speed. It is not the same as the take-off run available or the accelerate-stop distance. Certification rules require this 50 ft screen height for the all-engines case.

Question 2Take-off performance

The take-off run available (TORA) is best described as the length of runway declared available and suitable for:

  1. the accelerate-stop manoeuvre only
  2. the ground run of an aeroplane taking off Correct answer.
  3. the climb to 1500 ft after lift-off
  4. the landing roll after touchdown

Explanation

TORA is the declared runway length available for the ground run of an aeroplane taking off, measured from the start of the take-off to the end of the runway. It does not include clearway or stopway. Landing distance and airborne climb segments are separate declared distances.

Question 3Take-off performance

A clearway may be included in take-off calculations because it allows:

  1. a lower V1 to be used
  2. a reduction in the required screen height
  3. an increase in the take-off distance available Correct answer.
  4. a reduction of the accelerate-stop distance

Explanation

Clearway is an area beyond TORA over which an aeroplane can climb to the required screen height, so it increases the take-off distance available. It does not physically support the aeroplane, so it cannot be used to shorten the ground run or the accelerate-stop distance. Its effect is to permit a longer airborne segment within the declared distance.

Question 4Take-off performance

At a given mass, increasing the aerodrome pressure altitude will normally cause the take-off ground roll to:

  1. increase because of higher true airspeed for the same IAS Correct answer.
  2. decrease because the engine produces more thrust
  3. decrease because of lower air density
  4. remain unchanged because mass is constant

Explanation

Higher pressure altitude reduces air density, so a higher true airspeed is required to achieve the same indicated airspeed and lift. Thrust from a piston or jet engine also generally decreases with altitude. Both effects lengthen the ground roll.

Question 5Take-off performance

For a given indicated airspeed on take-off, a higher outside air temperature will result in:

  1. a longer take-off distance because density is lower Correct answer.
  2. no change in take-off distance
  3. a shorter take-off distance because the air is thinner
  4. a lower lift-off indicated airspeed

Explanation

Rising temperature lowers air density at constant pressure, so the true airspeed and ground speed corresponding to a given IAS increase. Engine thrust also typically decreases in hot conditions. The combined result is a longer take-off distance.

Question 6Take-off performance

An increase in take-off mass, with all other factors constant, will:

  1. have no effect on the take-off distance
  2. increase the take-off distance and increase V1 in all cases
  3. decrease the take-off distance because of greater inertia
  4. increase the take-off distance and generally increase the speeds Correct answer.

Explanation

Greater mass requires more lift and therefore higher speeds, and it reduces acceleration, so the ground roll and total distance both grow. Take-off reference speeds generally rise with mass. This is a fundamental relationship used in all take-off charts.

Question 7Take-off performance

A headwind component, compared with still air at the same mass and conditions, will:

  1. decrease the ground distance covered during take-off Correct answer.
  2. increase the ground roll but not the air distance
  3. increase the true airspeed needed for lift-off
  4. increase the accelerate-stop distance

Explanation

A headwind reduces the ground speed for a given indicated airspeed, so the ground distance needed to reach lift-off speed is reduced. The airborne segment is also shortened in ground terms. Take-off performance charts normally provide a wind correction to be applied to the still-air distance.

Question 8Take-off performance

When using a take-off chart that gives a still-air distance, a tailwind component must be treated as:

  1. no change because wind does not affect airspeed
  2. a reduction in the screen height
  3. an increase in the take-off distance Correct answer.
  4. a decrease in the take-off distance

Explanation

A tailwind increases the ground speed for a given indicated airspeed, so more runway is covered during both the ground roll and the airborne segment. Chart corrections therefore add distance for tailwind. Many operators prohibit take-off with a tailwind above a specified limit.

Question 9Take-off performance

A runway slope that rises in the direction of take-off will:

  1. lengthen the take-off distance Correct answer.
  2. have no effect if the wind is calm
  3. shorten the take-off distance
  4. reduce the required V1

Explanation

An upslope opposes acceleration and adds a gravity component that must be overcome, so the ground roll increases. Charts provide a slope correction, usually expressed as a percentage gradient. Downslope has the opposite effect.

Question 10Take-off performance

V1 is defined as the speed at which, if an engine failure occurs, the pilot can:

  1. always stop within the runway remaining
  2. continue the take-off and reach 35 ft at the end of the take-off distance available, or stop within the accelerate-stop distance available Correct answer.
  3. climb at VY with one engine inoperative
  4. safely retract flaps

Explanation

V1 is the decision speed: at or above it the take-off can be continued to the required screen height within the available distance, and at or below it the aeroplane can be stopped within the accelerate-stop distance. It is a balanced compromise between these two requirements.

Question 11Take-off performance

VR is the speed at which the pilot should:

  1. start the take-off roll
  2. begin to rotate the aeroplane to the take-off attitude Correct answer.
  3. retract the landing gear
  4. reduce thrust to climb power

Explanation

VR is the rotation speed, at which the pilot initiates a pitch input to raise the nose to the take-off attitude. Rotation at VR leads to lift-off at VLOF shortly afterwards. Rotating too early or too late affects the take-off distance and obstacle clearance.

Question 12Take-off performance

V2 is best described as:

  1. the speed for best angle of climb with all engines
  2. the maximum speed for retracting flaps
  3. the minimum control speed on the ground
  4. the take-off safety speed to be attained by 35 ft with one engine inoperative Correct answer.

Explanation

V2 is the take-off safety speed that must be achieved by the 35 ft point in the one-engine-inoperative case. It provides adequate control and climb performance. It is not the same as VX or the ground minimum control speed.

Question 13Take-off performance

If the take-off mass is reduced, the balanced field length normally:

  1. becomes equal to the landing distance
  2. decreases Correct answer.
  3. increases
  4. stays the same

Explanation

A lighter aeroplane accelerates faster and needs lower speeds, so both the accelerate-stop distance and the continue distance shrink. The balanced field length, where these two are equal, therefore decreases. This is why performance-limited take-off mass is calculated for a given runway.

Question 14Take-off performance

The term 'balanced field length' refers to the situation where:

  1. the clearway equals the stopway
  2. the take-off distance available equals the landing distance available
  3. the accelerate-stop distance equals the take-off distance required Correct answer.
  4. the take-off run equals the airborne segment

Explanation

Balanced field length occurs when the distance to accelerate and stop after an engine failure at V1 equals the distance to continue the take-off to the screen height. At this point V1 is optimised for the field. It is a performance concept, not a comparison with landing distance.

Question 15Take-off performance

An obstacle close to the end of the take-off distance available may require the operator to:

  1. increase V1 to improve climb gradient
  2. retract flaps earlier than normal
  3. increase the screen height to 100 ft
  4. reduce the take-off mass so the net flight path clears the obstacle Correct answer.

Explanation

If the net take-off flight path does not clear obstacles, the aeroplane must be lighter so that the climb gradient improves and the path rises above the obstacle. Alternatively the departure procedure may change. Mass reduction is the usual performance solution.

Question 16Take-off performance

The net take-off flight path used for obstacle clearance is obtained by:

  1. assuming a climb gradient of 3.3%
  2. using the all-engines climb gradient
  3. adding a margin to the gross gradient
  4. reducing the gross gradient by a fixed percentage Correct answer.

Explanation

The net flight path is the gross one-engine-inoperative gradient reduced by a fixed decrement (0.8% for two-engine aeroplanes, 0.9% for three, 1.0% for four). This provides a conservative margin for pilot technique and conditions. Obstacles must be cleared by the net path.

Question 17Take-off performance

During the take-off with one engine failing at V1, the second-segment climb requirement for a twin-engine aeroplane is a gross gradient of at least:

  1. 2.4%
  2. 3.3% Correct answer.
  3. 5.0%
  4. 1.0%

Explanation

For two-engine aeroplanes the second-segment gross gradient requirement is 2.4%, but the commonly quoted figure of 3.3% applies to three-engine types. Care is needed: the twin-engine value is 2.4%. The second segment ends when the aeroplane reaches 400 ft above the take-off surface.

Question 18Take-off performance

The take-off flight path begins at the end of the take-off distance and ends no lower than:

  1. the single-engine absolute ceiling
  2. 1500 ft above the take-off surface Correct answer.
  3. 400 ft above the take-off surface
  4. the acceleration altitude of 1000 ft

Explanation

The take-off flight path extends from 35 ft (or the end of the take-off distance) to at least 1500 ft above the take-off surface. It must clear all obstacles by the required margins. Above 1500 ft the en-route climb requirements apply.

Question 19Take-off performance

An aeroplane is performance-limited by a wet runway. Compared with a dry runway, the effect on the take-off distance required is generally:

  1. a decrease because water cools the tyres
  2. no change because the airspeed is the same
  3. an increase because of reduced braking and increased rolling friction Correct answer.
  4. a decrease in V1 in all cases

Explanation

On a wet runway, braking is less effective and spray and rolling resistance increase, so the accelerate-stop distance grows. Charts often require an increase in the field length or a reduction in mass. The take-off distance itself is also affected by reduced friction during the roll.

Question 20Take-off performance

Contaminated runway performance data are used because contamination:

  1. only affects landing performance
  2. may significantly reduce acceleration and braking effectiveness Correct answer.
  3. improves acceleration by reducing friction
  4. is only relevant below 10 °C

Explanation

Standing water, slush, snow or ice increases drag on the wheels and reduces braking friction, so both acceleration and stopping are degraded. Approved contaminated-runway data must be used. The effect can be very large and is not limited to cold conditions.

Question 21Take-off performance

In a take-off chart, the 'assumed temperature' method is used to:

  1. reduce thrust for a given mass while respecting performance limits Correct answer.
  2. calculate the landing distance
  3. determine the actual outside air temperature
  4. set the altimeter subscale

Explanation

The assumed temperature method allows a reduced thrust take-off by treating the actual conditions as if they were warmer. The resulting performance must still meet all requirements. It is a means of using less than maximum thrust for a given mass and runway.

Question 22Take-off performance

For a given mass and runway, if the wind changes from a 10 kt headwind to a 10 kt tailwind, the take-off distance required will:

  1. decrease
  2. decrease then increase
  3. remain the same
  4. increase Correct answer.

Explanation

A headwind reduces ground speed and therefore the ground distance covered, while a tailwind increases it. Changing from headwind to tailwind therefore increases the distance required substantially. Charts provide separate corrections for headwind and tailwind.

Question 23Take-off performance

An aeroplane must clear an obstacle 2000 m from the start of the take-off run. The take-off distance required to 35 ft is 1800 m. Which statement is correct?

  1. The obstacle can be ignored because it is beyond the screen height
  2. The net flight path must be checked from the end of the take-off distance to the obstacle Correct answer.
  3. No check is needed if the runway is dry
  4. The obstacle is automatically cleared because the take-off distance is shorter

Explanation

The take-off distance ends at 35 ft, but the obstacle lies beyond that point, so the net take-off flight path must be assessed from the end of the take-off distance to the obstacle. The aeroplane must clear it by the required margin. Being beyond the screen point does not remove the requirement.

Question 24Take-off performance

Which combination of conditions will produce the longest take-off distance required, all else equal?

  1. High mass, low altitude, cold day, headwind
  2. Low mass, low altitude, cold day, headwind
  3. High mass, high altitude, hot day, tailwind Correct answer.
  4. Low mass, high altitude, cold day, tailwind

Explanation

Each of high mass, high pressure altitude, high temperature and tailwind increases the take-off distance. Combining them gives the worst case. Low mass, low altitude, cold temperature and headwind all reduce the distance.

Question 25Take-off performance

The take-off distance available (TODA) is defined as:

  1. TORA plus any clearway Correct answer.
  2. TORA plus any stopway
  3. the runway length plus the runway end safety area
  4. the accelerate-stop distance available

Explanation

TODA equals the take-off run available plus any clearway declared, up to a maximum of half the TORA. Clearway is included because it allows the airborne segment to be completed within the declared distance. Stopway is used for ASDA, not TODA.

Question 26Take-off performance

The take-off run available (TORA) is defined as the length of runway declared available and suitable for which operation?

  1. The accelerate-stop manoeuvre only
  2. The landing roll after a rejected take-off
  3. The complete take-off including the initial climb
  4. The ground run of an aeroplane on take-off Correct answer.

Explanation

The take-off run available is the length of runway declared available and suitable for the ground run of an aeroplane on take-off. It ends at the last point where the wheels can leave the surface, not at any airborne segment. Climb segments and the landing roll are covered by different declared distances.

Question 27Take-off performance

The take-off distance available (TODA) consists of the take-off run available plus which additional element?

  1. The landing distance available
  2. The runway end safety area
  3. The stopway
  4. The clearway Correct answer.

Explanation

TODA is the take-off run available plus the length of any clearway provided. The clearway is an area beyond the runway over which the aeroplane can climb to 35 ft. A stopway is used for accelerate-stop distance, not for TODA.

Question 28Take-off performance

Which speed must be reached by the end of the take-off distance available so that the aeroplane can continue the climb to 35 ft?

  1. V2 Correct answer.
  2. VR
  3. V1
  4. VLOF

Explanation

The take-off distance available must allow the aeroplane to reach V2 by the end of that distance, with the aeroplane at 35 ft above the surface. V2 is the take-off safety speed that guarantees the required climb gradient. V1 and VR are earlier decision and rotation speeds.

Question 29Take-off performance

In the take-off distance required, the air distance from lift-off to 35 ft is affected most directly by which factor?

  1. The runway surface condition
  2. The tyre pressure
  3. The brake energy absorption limit
  4. The wind gradient and screen height Correct answer.

Explanation

The airborne segment of the take-off distance depends on the speed and the climb gradient achieved between lift-off and 35 ft. Wind gradient and the required screen height change that airborne distance directly. Surface condition and brake energy affect the ground phase rather than the air phase.

Question 30Take-off performance

An aeroplane has a take-off run required of 1800 m on a dry runway. The operator applies a 15 percent increase to allow for the wet runway condition. What is the resulting take-off run required?

  1. 1890 m
  2. 2160 m
  3. 2070 m Correct answer.
  4. 1980 m

Explanation

A 15 percent increase is calculated by multiplying the dry value by 1.15. Thus 1800 m times 1.15 equals 2070 m. The additive increment is 270 m, which is 15 percent of the original distance.

Question 31Take-off performance

An aeroplane must clear an obstacle located 2400 m from the start of the take-off run. The take-off distance required to 35 ft is 2100 m, and the net take-off flight path must clear the obstacle by 35 ft. If the net flight path reaches 35 ft at 2100 m, what is the margin in horizontal distance between the point the net flight path reaches 35 ft and the obstacle?

  1. 450 m
  2. 150 m
  3. 300 m Correct answer.
  4. 600 m

Explanation

The net take-off flight path reaches 35 ft at the end of the take-off distance, which is 2100 m from the start. The obstacle is at 2400 m. The horizontal margin is therefore 2400 m minus 2100 m, which equals 300 m.

Question 32Take-off performance

A twin-engine aeroplane has a second-segment net climb gradient requirement of 2.4 percent. If the gross gradient achieved is 3.2 percent, what is the net gradient available for obstacle clearance?

  1. 3.2 percent
  2. 2.4 percent
  3. 5.6 percent
  4. 0.8 percent Correct answer.

Explanation

The net gradient is the gross gradient reduced by the climb gradient decrement. For a twin-engine aeroplane the decrement is 0.8 percent, so 3.2 percent minus 0.8 percent equals 2.4 percent. The net gradient is the value actually used against obstacles.

Question 33Take-off performance

An aeroplane has a take-off mass of 60 000 kg and a reference take-off distance of 2000 m at that mass. If the take-off distance varies approximately with the square of the mass, what is the approximate take-off distance at a mass of 66 000 kg?

  1. 2200 m
  2. 2420 m Correct answer.
  3. 2640 m
  4. 2000 m

Explanation

The mass ratio is 66 000 divided by 60 000, which equals 1.10. Squaring this ratio gives 1.21, and 2000 m times 1.21 equals 2420 m. This square relationship reflects the combined change in acceleration and lift-off speed.

Question 34Take-off performance

What is the effect of a 10 kt tailwind component on the take-off distance required compared with still air at the same mass and conditions?

  1. The distance is unchanged because airspeed determines performance
  2. The distance is unchanged because the wind affects only the airborne segment
  3. The distance increases because the aeroplane must travel farther over the ground to reach the same airspeeds Correct answer.
  4. The distance decreases because the airspeed is reached sooner over the ground

Explanation

A tailwind means the aeroplane must cover more ground to achieve the same airspeeds for rotation and lift-off. Both the ground roll and the airborne segment are lengthened. The take-off distance required therefore increases, and take-off charts must be corrected accordingly.

Question 35Take-off performance

Why is the take-off distance required normally limited to the take-off distance available, rather than the take-off run available alone?

  1. Because the aeroplane must reach 35 ft by the end of the take-off distance available, which includes the airborne segment Correct answer.
  2. Because the stopway limits the take-off run available
  3. Because the clearway is used only for landing
  4. Because the take-off run available is always longer than the take-off distance available

Explanation

The take-off distance required includes the ground roll plus the airborne distance to 35 ft. This total must fit within the take-off distance available, which may include a clearway. The take-off run available alone covers only the ground phase.

Question 36Take-off performance

An aeroplane must clear an obstacle 1500 m from the start of the take-off run. The net take-off flight path reaches 35 ft at 1200 m and thereafter climbs at a net gradient of 2.5 percent. What is the approximate height of the net flight path above the obstacle?

  1. 35 ft plus 7.5 m Correct answer.
  2. 35 ft plus 75 m
  3. 35 ft only
  4. 35 ft plus 30 m

Explanation

The horizontal distance from the 35 ft point to the obstacle is 1500 m minus 1200 m, which equals 300 m. At a net gradient of 2.5 percent, the gain is 0.025 times 300 m, which equals 7.5 m. Adding the 35 ft screen height gives the net height above the obstacle.

Question 37Take-off performance

On a take-off chart, the field length limited take-off mass is the mass at which which condition is exactly satisfied?

  1. The second-segment gradient equals zero
  2. The accelerate-stop distance equals the take-off run available
  3. The lift-off speed equals V2
  4. The take-off distance required equals the take-off distance available Correct answer.

Explanation

The field length limited mass is the maximum mass at which the take-off distance required exactly equals the take-off distance available. At higher masses the aeroplane could not reach 35 ft within the available distance. This limit may be more restrictive than the climb or tyre speed limits.

Question 38Take-off performance

A runway is contaminated with standing water. Compared with a dry runway, which combination best explains the change in take-off performance?

  1. Increased rolling resistance and reduced braking friction, both increasing the distance
  2. Reduced rolling resistance and reduced braking friction, both increasing the distance Correct answer.
  3. Reduced rolling resistance and increased braking friction, both reducing the distance
  4. Increased rolling resistance and increased braking friction, both reducing the distance

Explanation

Standing water reduces tyre-to-surface friction and also lowers rolling resistance, but the dominant effect is a large increase in the accelerate-stop distance and a decrease in the achievable V1. Take-off performance data for contaminated runways account for this net degradation. The overall result is a longer distance required.

Question 39Take-off performance

What is the purpose of the take-off mass limitation known as the tyre speed limit?

  1. To ensure the brakes can absorb the rejected take-off energy
  2. To ensure the nosewheel steering remains effective on the runway
  3. To ensure the tyres do not exceed their certified ground speed at lift-off Correct answer.
  4. To ensure the tyres do not exceed their certified inflation pressure in cruise

Explanation

The tyre speed limit restricts the ground speed at lift-off to the certified maximum for the tyres. Because ground speed at lift-off increases with mass, this becomes a limiting mass on long runways or with a tailwind. It is separate from the brake energy limit.

Question 40Take-off performance

During take-off planning, an aeroplane's V1 is increased while all other speeds and conditions stay the same. What is the effect on the accelerate-stop distance and the take-off distance required?

  1. The accelerate-stop distance decreases while the take-off distance required increases.
  2. Both the accelerate-stop distance and the take-off distance required decrease.
  3. The accelerate-stop distance increases while the take-off distance required decreases.
  4. Both the accelerate-stop distance and the take-off distance required increase. Correct answer.

Explanation

V1 is the decision speed: if an engine fails at V1 the crew must be able to stop within the accelerate-stop distance available, and the continued take-off must also be achievable. Raising V1 means the failure is recognised at a higher speed, so more energy must be dissipated in the stop, lengthening the accelerate-stop distance. The same higher speed at which the aeroplane becomes committed and continues means a longer airborne segment to 35 ft, so the take-off distance required also grows.

Question 41Climb performance

In a steady climb, the rate of climb is determined by which relationship?

  1. Lift divided by drag multiplied by true airspeed
  2. Excess thrust multiplied by true airspeed divided by weight Correct answer.
  3. Excess power divided by true airspeed
  4. Total thrust multiplied by true airspeed divided by weight

Explanation

Rate of climb equals excess power divided by weight, and excess power is excess thrust multiplied by true airspeed. Only the thrust component beyond that needed to balance drag contributes to climbing. This is why climb performance is quoted as a power or thrust margin.

Question 42Climb performance

For a turbojet aeroplane, the maximum rate of climb in the climb segment occurs at which condition?

  1. Maximum excess thrust condition Correct answer.
  2. Maximum lift coefficient
  3. Minimum fuel flow condition
  4. Maximum angle-of-attack before stall

Explanation

For a jet, thrust is approximately constant with speed, so the best rate of climb occurs where excess thrust (thrust minus drag) is greatest, which is at the minimum-drag speed. Best angle of climb occurs at a higher speed where the excess-thrust-to-weight ratio is greatest. These two speeds are therefore not identical for a jet.

Question 43Climb performance

Which speed gives the greatest angle of climb for a propeller aeroplane?

  1. The speed for minimum power required
  2. The speed for maximum excess power
  3. The speed for maximum excess thrust divided by weight Correct answer.
  4. The speed for minimum drag

Explanation

Climb angle depends on the ratio of excess thrust to weight, so the steepest climb occurs where excess thrust per unit weight is greatest. For a propeller aircraft this is close to the minimum-drag speed. Best rate of climb, by contrast, uses excess power.

Question 44Climb performance

As an aeroplane climbs at a constant indicated airspeed and constant Mach number schedule, what happens to the true airspeed?

  1. It remains constant throughout the climb
  2. It decreases only above the tropopause
  3. It increases as the air density decreases Correct answer.
  4. It decreases as the air density decreases

Explanation

Indicated airspeed reflects dynamic pressure, so holding it constant while density falls requires true airspeed to rise. The aeroplane therefore covers more ground per unit time at altitude for the same indicated speed. This is why climb schedules are usually given as IAS below the crossover altitude and Mach above it.

Question 45Climb performance

Which factor causes the rate of climb to decrease as altitude increases at a fixed indicated airspeed?

  1. Increasing air density and decreasing stall speed
  2. Increasing true airspeed and decreasing engine thrust available Correct answer.
  3. Increasing lift coefficient and decreasing drag
  4. Decreasing weight of the aeroplane

Explanation

In a climb at constant IAS, true airspeed rises as density falls, so more power is needed to overcome drag. At the same time, engine thrust or power available typically decreases with altitude. Both effects reduce the excess power and therefore the rate of climb.

Question 46Climb performance

The absolute ceiling of an aeroplane is the altitude at which which condition applies?

  1. The maximum rate of climb is zero Correct answer.
  2. The stall speed equals the never-exceed speed
  3. The service ceiling is exceeded by 5000 feet
  4. The rate of climb is 100 feet per minute

Explanation

The absolute ceiling is the theoretical altitude where excess power vanishes, so the maximum rate of climb becomes zero. In practice it cannot be reached in a finite time, which is why the service ceiling is used operationally. The service ceiling is defined by a small residual rate of climb.

Question 47Climb performance

The service ceiling of a transport aeroplane is normally defined as the altitude at which the maximum rate of climb is:

  1. 1000 feet per minute
  2. 100 feet per minute Correct answer.
  3. 500 feet per minute
  4. Zero feet per minute

Explanation

The service ceiling is conventionally the altitude where the maximum rate of climb has fallen to 100 feet per minute. This gives a practical, measurable limit rather than the unattainable absolute ceiling. Certification and operating rules use this value for planning.

Question 48Climb performance

During a climb, an aeroplane is accelerated from the best angle-of-climb speed to the best rate-of-climb speed. What is the effect?

  1. Both the climb angle and the rate of climb decrease
  2. Both the climb angle and the rate of climb increase
  3. The climb angle decreases and the rate of climb increases Correct answer.
  4. The climb angle increases and the rate of climb decreases

Explanation

Best angle of climb is achieved at a lower speed than best rate of climb. Accelerating toward the best rate speed trades some excess thrust per unit weight for more excess power, so the climb becomes shallower but faster vertically. The two speeds represent different optimisations.

Question 49Climb performance

What is the effect of an increase in aeroplane mass on the rate of climb, all other factors unchanged?

  1. The rate of climb increases at high altitude only
  2. The rate of climb decreases because more lift and more induced drag are required Correct answer.
  3. The rate of climb is unchanged because thrust is unaffected
  4. The rate of climb increases because the wing loading rises

Explanation

A heavier aeroplane needs a higher lift coefficient at a given speed, which raises induced drag and the thrust required. The excess thrust and excess power therefore fall, reducing both the climb angle and the rate of climb. The speed for best climb also increases with mass.

Question 50Climb performance

Which statement correctly describes the effect of extending flaps on climb performance?

  1. Flaps increase the maximum lift coefficient and always improve the climb gradient
  2. Flaps have no effect on climb because they only affect landing
  3. Flaps increase the rate of climb by reducing the stall speed
  4. Flaps increase drag and reduce the excess power available for climbing Correct answer.

Explanation

Flap extension raises lift at a given speed but also adds substantial drag, particularly at large deflections. The extra drag reduces excess thrust and excess power, so climb gradient and rate of climb generally deteriorate. This is why take-off flap settings are kept small.