Category: Aircraft Performance Objective Questions

Aircraft Performance Multiple Choice Questions on “Measurement of Air Data”.

1. ADD stands for ____________
a) Airflow Direction Detector
b) Aircraft Direction Detector
c) Airflow Density Detector
d) Aircraft Density Detector
Answer: a
Clarification: ADD stands for airflow direction detector. The function of airflow direction detector is to sense the local flow direction relative to the aircraft body axes and these are the part of the aircraft system.

2. The essential requirement of air data measurement is the state of the atmosphere in which the aircraft is flying.
a) True
b) False
Answer: a
Clarification: The essential requirement of air data measurement is the state of the atmosphere in which the aircraft is flying. The second essential requirement of air data measurement is the relative motion between the aircraft and the air mass.

3. Air data measurement does not consider the relative motion between the aircraft and the air mass.
a) True
b) False
Answer: b
Clarification: The essential requirement of air data measurement is the relative motion between the aircraft and the air mass. The second essential requirement of air data measurement is the state of the atmosphere in which the aircraft is flying.

4. ADC stands for _____________
a) Aircraft Data Computer
b) Air Data Computer
c) Air Density Computer
d) Air Data Computation
Answer: b
Clarification: ADC stands for air data computer. This is a device installed in aircraft to convert pressure into electrical signals. The conversion is done with the help of transducers which help in processing the electrical signals.

5. ADC is a pure mechanical instrument installed in an aircraft.
a) True
b) False
Answer: b
Clarification: ADC is an electrical power based system and not a pure mechanical instrument. ADC stands for air data computer. This is a device installed in aircraft to convert pressure into electrical signals. The conversion is done with the help of transducers which help in processing the electrical signals.

6. 1 knot=________km/hr
a) 1.773
b) 1.852
c) 1.609
d) 1.414
Answer: b
Clarification: 1 knot=1.852 km/hr. Knot stands for nautical miles per hour. Conversion of nautical miles to kilometers is 1 nautical mile=1.852km. Hence, 1 knot=1.852 km/hr.

7. 1 foot=_________meters
a) 3.28084
b) 0.3678
c) 0.3048
d) 3.4567
Answer: c
Clarification: 1 foot=0.3048 meters. Foot is unit of length or distance in general system whereas meter is a standard unit. Meter is the S.I unit of length in MKS system and used by everyone throughout the world.

8. Which of the following are measured by Pitot – static system in air data system?
a) Height, mach number, airspeed
b) Pressure, density, temperature
c) Height, mach number, pressure
d) Height, mach number, density
Answer: a
Clarification: Height, mach number, airspeed are the quantities measured by Pitot – static system in air data system. They convert the air fed pressures into the movement of a pointer in mechanical instrument.

9. Pitot-static system is a primary flight instrument.
a) True
b) False
Answer: b
Clarification: Pitot-static system is not a primary measuring instrument. The altimeter, indicator and mach meter are the primary flight instruments. The secondary flight instruments are air temperature sensor and ADD’s.

10. ADD is a secondary flight instrument.
a) True
b) False
Answer: a
Clarification: The secondary flight instruments are air temperature sensor and ADD’s. The altimeter, indicator and mach meter are the primary flight instruments. The primary instruments are mechanical instruments whereas the secondary instruments are electrical power based instruments.

Aircraft Performance Multiple Choice Questions on “Aerodynamic Relationships”.

1. The minimum drag speed is given by ___________
a) (big(frac{2W}{rho S}big)^{frac{1}{2}}big(frac{K}{C_{Dz}}big)^frac{1}{4})
b) (big(frac{2W}{gamma rho S}big)^{frac{1}{2}}big(frac{K}{C_{Dz}}big)^frac{1}{4})
c) (big(frac{2W}{rho S}big)^{frac{1}{2}}big(frac{K}{C_{Dz}}big)^frac{1}{2})
d) (big(frac{2W}{gamma rho S}big)^{frac{1}{2}}big(frac{K}{C_{Dz}}big)^frac{1}{2})
Answer: a
Clarification: The correct formula for minimum drag speed is given by (big(frac{2W}{rho S}big)^{frac{1}{2}}big(frac{K}{C_{Dz}}big)^frac{1}{4}) where W is weight, ρ is density, K is constant, S is span area and C_Dz is coefficient of lift dependent drag.

2. The minimum drag mach number is given by ___________
a) (big(frac{2W}{rho S}big)^{frac{1}{2}}big(frac{K}{C_{Dz}}big)^frac{1}{4})
b) (big(frac{2W}{gamma rho S}big)^{frac{1}{2}}big(frac{K}{C_{Dz}}big)^frac{1}{4})
c) (big(frac{2W}{rho S}big)^{frac{1}{2}}big(frac{K}{C_{Dz}}big)^frac{1}{2})
d) (big(frac{2W}{gamma rho S}big)^{frac{1}{2}}big(frac{K}{C_{Dz}}big)^frac{1}{2})
Answer: b
Clarification: The correct formula for minimum drag mach number is given by (big(frac{2W}{gamma rho S}big)^{frac{1}{2}}big(frac{K}{C_{Dz}}big)^frac{1}{4}) where W is weight, ρ is density, K is constant, S is span area, γ is ratio of specific heats and C_Dz is coefficient of lift dependent drag.

3. At steady state flight condition
a) T>D
b) Tc) T=D
d) T≠D
Answer: c
Clarification: At steady state flight condition the thrust produced by the aircraft is same as the drag produced by the aircraft i.e. T=D. At this state the minimum power speed is given by (frac{1}{sqrt[4]{3}})=V_md where V_md is minimum drag speed.

4. Which of the following is the correct relation between minimum power speed and minimum drag speed?
a) V_mp=(frac{1}{sqrt[2]{3}})V_md
b) V_mp=(frac{1}{sqrt[4]{3}})V_md
c) V_mp=(frac{1}{sqrt[3]{3}})V_md
d) V_mp=(frac{1}{sqrt[4]{5}})V_md
Answer: b
Clarification: At steady state flight condition the thrust produced by the aircraft is same as the drag produced by the aircraft i.e. T=D. The relation between minimum drag speed and minimum power speed is given by V_mp=(frac{1}{sqrt[4]{3}})V_md where V_md is minimum drag speed and V_mp is minimum power speed.

5. What is the value of minimum power speed when minimum drag speed is 300m/s?
a) 173.21 m/s
b) 227.95 m/s
c) 134.16 m/s
d) 200.62 m/s
Answer: b
Clarification: The correct answer is 227.95 m/s. Given V_md is 300m/s. From the formula V_mp=(frac{1}{sqrt[4]{3}})V_md substitute the values.
On substituting we get, V_mp=(frac{1}{sqrt[4]{3}})*300
V_mp=227.95m/s.

6. Airspeed with minimum power speed relates to the performance of the aircraft with power producing engine.
a) True
b) False
Answer: a
Clarification: Airspeed with minimum power relates to the performance of the aircraft with power producing engine whereas minimum drag speed relates to the performance of aircraft with thrust-producing engine.

7. In a glider the engine used is thrust producing engine.
a) True
b) False
Answer: b
Clarification: Airspeed with minimum power relates to the performance of the aircraft with power producing engine whereas minimum drag speed relates to the performance of aircraft with thrust-producing engine. In a glider the engine uses both minimum power speed and minimum drag speed but does not have any engine present.

8. What is the relative airspeed of an aircraft whose airspeed and minimum drag speed are 500m/s and 150m/s?
a) 3.33
b) 0.3
c) 33.33
d) 0.333
Answer: a
Clarification: The answer is 3.33. Given, airspeed is 500m/s and minimum drag speed is 150m/s. From the formula u=(frac{V}{V_{md}}) where V is airspeed and V_md is minimum drag speed. On substituting the values we get u= (frac{500}{150})
u=3.33.

9. What will be the drag to minimum drag ratio when the relative airspeed is 3.33?
a) 5.49
b) 1.51
c) 5.59
d) 1.82
Answer: c
Clarification: The answer is 5.59. Given u=3.33. From the equation (frac{D}{D_{min}})=(frac{1}{2}big[u^2+frac{1}{u^2}big])where (frac{D}{D_{min}}) is drag to minimum drag ratio and u is relative airspeed. On substituting the values,
We get (frac{D}{D_{min}})=(frac{1}{2}big[3.33^2+frac{1}{3.33^2}big])
On solving we get (frac{D}{D_{min}})=5.59.

10. Which of the following is the correct performance equation?
a) (big[frac{lambda}{u}+τbig]+frac{1}{2}big[u^2+frac{1}{u^2}big])=E_max(big{singamma_2-frac{V}{g}big})
b) (big[frac{lambda}{u}+τbig]-frac{1}{2}big[u^2+frac{1}{u^2}big])=E_max(big{singamma_2-frac{V}{g}big})
c) (big[frac{lambda}{u}+τbig]+frac{1}{2}big[u^2+frac{1}{u^2}big])=E_max(big{singamma_2+frac{V}{g}big})
d) (big[frac{lambda}{u}+τbig]-frac{1}{2}big[u^2+frac{1}{u^2}big])=E_max(big{singamma_2+frac{V}{g}big})
Answer: d
Clarification: The correct equation is (big[frac{lambda}{u}+τbig]-frac{1}{2}big[u^2+frac{1}{u^2}big])=E_max(big{singamma_2+frac{V}{g}big}) where λ is dimensionless power, u is relative speed, τ is dimensionless thrust, E_max is maximum efficiency, sinγ₂ is horizontal component, V is airspeed and g is gravitational force.

Aircraft Performance Multiple Choice Questions on “Minimum Fuel Climb”.

1. Which of the following is the formula for specific climb?
a) SC=(frac{dH}{Q_f})
b) SC=(frac{dH}{dt})
c) SC=(frac{dH/dt}{Q_f})c
d) SC=(frac{dH/dt}{Q_f})
Answer: c
Clarification: The formula for specific climb is given by SC=(frac{dH/dt}{Q_f}) where SC is specific thrust, (frac{dH}{dt}) is rate change of height with respect to time and Q_f is fuel flow. The specific climb is calculated in the units of ft/kg.

2. The unit of specific heat is ft/kg.
a) True
b) False
Answer: a
Clarification:The formula for specific climb is given by SC=(frac{dH/dt}{Q_f}) where SC is specific thrust, (frac{dH}{dt}) is rate change of height with respect to time and Q_f is fuel flow. The specific climb is calculated in the units of ft/kg.

3. What is the value of specific climb when the value of (frac{dH}{dt})=1 and the fuel flow is 833.33 kg?
a) 0.0013ft/kg
b) 0.0012ft/kg
c) 0.0019ft/kg
d) 0.002ft/kg
Answer: b
Clarification: The answer is 0.0012ft/kg. The formula for specific climb is given by SC=(frac{dH/dt}{Q_f}). Given, (frac{dH}{dt})=1 and Q_f=833.33 kg. Substituting the values we get SC=(frac{1}{833.33}).
We get SC=0.0012ft/kg.

4. Which of the following characteristics are determined during flight trials of calculated fuel flow?
a) Fuel rate
b) Optimum climb speed
c) Airspeed
d) Altitude
Answer: b
Clarification: During the calculated fuel flow flight trials the optimum climb speed is calculated and then the specific climb function is known which helps in the determination of airspeed for a minimum fuel climb.

5. The minimum fuel climb occurs at the airspeed for best rate of climb.
a) True
b) False
Answer: a
Clarification: The minimum fuel climb occurs at the airspeed for best rate of climb. During the calculated fuel flow flight trials the optimum climb speed is calculated and then the specific climb function is known which helps in the determination of airspeed for a minimum fuel climb.

6. The thrust reduction during climb leads to ____________
a) increase in rate of climb
b) reduction in time of flight
c) increase in gradient of climb
d) decrease in climb gradient
Answer: d
Clarification: The thrust reduction during climb leads to reduction in rate and climb gradient and increases the time taken for the take-off of the aircraft. The minimum fuel climb occurs at the airspeed for best rate of climb.

7. What are the factors that affect the economic benefits of fuel climb?
a) Indirect operating costs
b) Direct operating costs
c) Annual pay to the airport
d) Tax pay
Answer: b
Clarification: The analysis of the economic benefits of a minimum climb will depend on the direct operating costs of the aircraft. Direct operating costs include the costs that are directly related to the operation of the flight during travel such as crew salary, seat cost, fuel costs etc.

8. In practical the specific fuel consumption is effected by the airspeed, mach number and temperature.
a) True
b) False
Answer: a
Clarification: In practical the specific fuel consumption is effected by the airspeed, mach number and temperature. These factors will optimize the minimum fuel climb of the aircraft. The analysis of the economic benefits of a minimum climb will depend on the direct operating costs of the aircraft.

9. In the calculation of the specific climb the specific fuel consumption is kept varying and the thrust or power is kept at maximum position.
a) True
b) False
Answer: a
Clarification: In the calculation of the specific climb the specific fuel consumption is kept constant and the thrust or power is kept at maximum position.The formula for specific climb is given by SC=(frac{dH/dt}{Q_f}) where SC is specific thrust, (frac{dH}{dt}) is rate change of height with respect to time and Q_f is fuel flow. The specific climb is calculated in the units of ft/kg.

10. Engines with low noise signature comply with the noise regulations and provide a better performance in the climb.
a) True
b) False
Answer: a
Clarification: Engines with low noise signature comply with the noise regulations and provide a better performance in the climb. This is because they can operate at higher thrust levels without exceeding the noise limits.

Aircraft Performance Multiple Choice Questions on “Measurement of Height”.

1. What is meant by altimeter reading?
a) It is the reading of individual mechanical instrument which calculates the pressure
b) It is the reading of individual electrical instrument which calculates the pressure
c) It is the reading of individual mechanical instrument which calculates the density
d) It is the reading of individual electrical instrument which calculates the density
Answer: a
Clarification: Altimeter reading is the reading of individual mechanical instrument which calculates the pressure. During these calculations some corrections are made to avoid errors that are caused due to mechanical tolerance.

2. What is meant by indicated altitude?
a) It is the pitot-static reading corrected for performance error
b) It is the altimeter reading corrected for instrument error
c) It is the pitot-static reading corrected for instrument error
d) It is the altimeter reading corrected for performance error
Answer: b
Clarification: Indicated altitude is the altimeter reading corrected for instrument error. The indicated altitude will be measured with reference to the appropriate altimeter datum pressure setting.

3. Altimeter indicates the height as a function of barometric static pressure in the atmosphere.
a) True
b) False
Answer: a
Clarification: Altimeter indicates the height as a function of barometric static pressure in the atmosphere. Altimeter reading is the reading of individual mechanical instrument which calculates the pressure. During these calculations some corrections are made to avoid errors that are caused due to mechanical tolerance.

4. What is meant by pressure altitude?
a) It is the indicated altitude measured with respect to appropriate datum pressure setting
b) It is the indicated altitude measured with respect to appropriate gauge pressure setting
c) It is the indicated altitude measured with respect to appropriate static pressure setting
d) It is the indicated altitude measured with respect to appropriate vacuum pressure setting
Answer: a
Clarification: Pressure altitude it is the indicated altitude measured with respect to appropriate datum pressure setting. It is corrected for static pressure error. This error is caused due to the static source being located within the disturbed pressure field caused due to presence of aircraft.

5. What is meant by geopotential height interval?
a) It is the pressure height interval measured by the pitot-static tube
b) It is the pressure height interval measured by the altimeter
c) It is the temperature height interval measured by the pitot-static tube
d) It is the temperature height interval measured by the altimeter
Answer: b
Clarification: Geopotential height interval it is the pressure height interval measured by the altimeter. Geopotential height interval is corrected for temperature difference from ISA model atmosphere.

6. The geopotential height of the isothermal lower stratosphere (i.e. at 11km) is given by __________
a) H=11000-(frac{RT_{11}}{g_0})ln((frac{p}{p_{11}}))
b) H=11000-(frac{RT_{11}}{g_0})ln((frac{p_{11}}{p}))
c) H=11000+(frac{RT_{11}}{g_0})ln((frac{p}{p_{11}}))
d) H=11000+(frac{RT_{11}}{g_0})ln((frac{p_{11}}{p}))
Answer: a
Clarification: The height of the isothermal lower stratosphere is given by H=11000-(frac{RT_{11}}{g_0})ln((frac{p}{p_{11}})) where,
H=geopotential height
R=characteristic gas constant
T₁₁=temperature at 11km
P₁₁=pressure at 11km
g₀=acceleration due to gravity
p=pressure.

7. Find the geopotential height of an aircraft flying sea level where L₀=-0.0065 k/m, p=30070.36Pa.
a) 9120 km
b) 9144 km
c) 9854 km
d) 9874 km
Answer: b
Clarification: The answer is 9144 km. Given L₀=-0.0065 k/m, p=30070.36 Pa.
We know T₀=288.15K, p₀=101325Pa, R=287 J/kg-K, g₀=9.81m/s².
From H=(frac{T_0}{l_0})[((frac{p}{p_0})^frac{-L_0R}{g_0})-1]
H=(frac{288.15}{-0.0065})[((frac{30070.36}{101325})^frac{-(-0.0065)*287}{9.81})-1]
H=9144 km.

8.The geopotential height in troposphere is given by __________
a) H=(frac{T_0}{l_0})[((frac{p}{p_0}))^{(frac{-L_0R}{g_0})}+1]
b) H=(frac{T_0}{l_0})[((frac{p}{p_0}))^{(frac{L_0R}{g_0})}-1]
c) H=(frac{T_0}{l_0})[((frac{p}{p_0}))^{(frac{-L_0R}{g_0})}-1]
d) H=(frac{T_0}{l_0})[((frac{p}{p_0}))^{(frac{L_0R}{g_0})}+1]
Answer: c
Clarification: The geopotential height in troposphere is given by H=(frac{T_0}{l_0})[((frac{p}{p_0}))^{(frac{-L_0R}{g_0})}-1] where
H=geopotential height
R=characteristic gas constant
T₀=temperature at 11km
P₀=pressure at 11km
g₀=acceleration due to gravity
p=pressure
L₀=lapse rate.

9. What is a barometric altimeter?
a) A device used to measure the height above a fixed level with the help of barometric pressure changes
b) A device used to measure the pressure above a fixed level with the help of barometric pressure changes
c) A device used to measure the height above a fixed level with the help of pitot tube pressure changes
d) A device used to measure the pressure above a fixed level with the help of pitot tube pressure changes
Answer: a
Clarification: Barometric altimeter is a device used to measure the height above fixed level with the help of barometric pressure changes. Barometric altimeter is calibrated as soon as the flight is reached to a known altitude, at this point the barometric altimeter will accurate to 1metre.

10. QNH is a sea-level pressure which is used to measure the height above sea level.
a) True
b) False
Answer: a
Clarification: QNH is a sea-level pressure which is used to measure the height above sea level with the help of altimeter, when the QNH is set in the aircraft then the altimeter reads altitudes above mean sea level.

11. The installation of QNH in an aircraft helps the altimeter in reading the heights above air field level whereas the installation of QFE in an aircraft helps the altimeter in reading the heights above mean sea level.
a) True
b) False
Answer: b
Clarification: The installation of QNH in an aircraft helps the altimeter in reading the heights above mean sea level whereas the installation of QFE in an aircraft helps the altimeter in reading the heights above air field level.

Aircraft Performance Multiple Choice Questions on “Descent Performance in Aircraft Operations – 1”.

1. In what proportion should the propulsive thrust be so that the aircraft will decelerate?
a) Thrust is less than airframe drag
b) Thrust is more than airframe drag
c) Greater airspeed
d) Less airspeed
Answer: a
Clarification: The aircraft will descend if the propulsive thrust is less than the airframe drag. The descend flight path can be varied from a shallow descent to a very steep descent either by reducing the engine thrust or by increasing airframe drag.

2. There are two ways of aircraft descend of an aircraft.
a) True
b) False
Answer: a
Clarification: The aircraft will descend if the propulsive thrust is less than the airframe drag. The descend flight path can be varied from a shallow descent to a very steep descent either by reducing the engine thrust or by increasing airframe drag.

3. What are the factors for that increase the drag in an aircraft?
a) Varying airspeed
b) Constant airspeed
c) Varying thrust
d) Varying fuel ratio
Answer: a
Clarification: The drag that is produced in the aircraft is increased by aerodynamic means or by varying the airspeed. The aircraft has a very wide range of descent path for the aircrafts. The aircraft will descend if the propulsive thrust is less than the airframe drag.

4. In the case of gliders, the descent is calculated by lift-drag ratio.
a) True
b) False
Answer: a
Clarification: In the case of gliders, the descent is calculated by lift-drag ratio. In this case the minimum rate of descent occurs at the minimum power speed and minimum gradient occurs at the minimum drag speed.

5. At which cases does descent of flow occur?
a) By flying the aircraft at airspeed less than minimum drag speed
b) By flying the aircraft at airspeed more than minimum drag speed
c) By flying the aircraft at airspeed less than maximum drag speed
d) By flying the aircraft at airspeed more than maximum drag speed
Answer: a
Clarification: The descent of an aircraft can happen at flying the aircraft at airspeed less than minimum drag speed. In this case the minimum rate of descent occurs at the minimum power speed and minimum gradient occurs at the minimum drag speed.

6. The flight path is unstable during __________
a) the aircraft flying at airspeed less than minimum drag speed
b) the aircraft flying at airspeed more than minimum drag speed
c) the aircraft flying at airspeed less than maximum drag speed
d) the aircraft flying at airspeed more than maximum drag speed
Answer: a
Clarification: The flight path is unstable during the aircraft flying at airspeed less than minimum drag speed. In this case the minimum rate of descent occurs at the minimum power speed and minimum gradient occurs at the minimum drag speed.

7. The flight path can be controlled by the use of __________
a) elevator
b) rudder
c) flaps
d) slats
Answer: a
Clarification: The flight path can be controlled by the use of elevator control only. If the aircraft is flying with airspeed greater than minimum drag speed then the flight path gradient of descent can be increased by increasing airspeed.

8. The flight path gradient of descent can be increased by increasing airspeed.
a) True
b) False
Answer: a
Clarification: The flight path can be controlled by the use of elevator control only. If the aircraft is flying with airspeed greater than minimum drag speed then the flight path gradient of descent can be increased by increasing airspeed.

9. By which of the methods the flight can be descended?
a) nose down pitch
b) nose uppitch
c) nose down and elevator
d) elevator and nose up
Answer: b
Clarification: The climb gradient is decreased by decrease in nose down pitch. This can be alone done by the elevator control. This is the situation of the airspeed less than minimum drag speed. If the aircraft is flying with airspeed greater than minimum drag speed then the flight path gradient of descent can be increased by increasing airspeed.

10. At the back side of the drag curve the rate of change of drag is negative.
a) True
b) False
Answer: a
Clarification: At the back side of the drag curve the rate of change of drag is negative. During this case the flight path gradient cannot be alone handled by the elevator control. If the aircraft is flying with airspeed greater than minimum drag speed then the flight path gradient of descent can be increased by increasing airspeed.