Category: Aircraft Performance Objective Questions

Aircraft Performance online test on “Measurement of Airflow Characteristics”.

1. What is the relation between pressure and density in an adiabatic air flow?
a) (frac{p_1}{p_2})=((frac{rho_1}{rho_2}))^{(frac{1}{gamma})}
b) (frac{p_1}{p_2})=((frac{rho_1}{rho_2}))^γ
c) (frac{p_1}{p_2})=((frac{rho_1}{rho_2}))^γ+1
d) (frac{p_1}{p_2})=((frac{rho_1}{rho_2}))^γ-1
Answer: b
Clarification: The relation between pressure and density in an adiabatic air flow is given by (frac{p_1}{p_2})=((frac{rho_1}{rho_2}))^γ where p₁, p₂ are pressure values and ρ₁, ρ₂ are density values and γ is the ratio of specific heat at constant pressure to that of specific heat at constant volume.

2. What is meant by airspeed?
a) The relative velocity between the aircraft and the air mass in which the aircraft is flying
b) The ratio of velocity between the aircraft and the air mass in which the aircraft is flying
c) The relative acceleration between the aircraft and the air mass in which the aircraft is flying
d) The ratio of velocity between the aircraft and the ground in which the aircraft is flying
Answer: a
Clarification: Airspeed is the relative velocity between the aircraft and the air mass in which the aircraft is flying. The unit of airspeed is knot. There are different types of airspeeds. They are ground speed, true airspeed, calibrated airspeed and indicated airspeed.

3. Airspeeds are of three types.
a) True
b) False
Answer: b
Clarification: Airspeeds are of four types. They are ground speed, true airspeed, calibrated airspeed and indicated airspeed. Airspeed is the relative velocity between the aircraft and the air mass in which the aircraft is flying. The unit of airspeed is knot.

4. Which of the following is the general equation that relates flow temperature to true airspeed?
a) C_pT+(frac{V^2}{2})=constant
b) C_pT-(frac{V^2}{2})=constant
c) C_vT+(frac{V^2}{2})=constant
d) C_vT-(frac{V^2}{2})=constant
Answer: a
Clarification: C_pT+(frac{V^2}{2})=constant is the general equation that relates flow temperature to true airspeed, where C_p=specific heat at constant pressure, T=temperature, V=true airspeed.

5. What is true airspeed?
a) relative speed of aircraft with respect to the surrounding air flow
b) relative speed of aircraft sound with respect to the surrounding air flow sound
c) moment of aircraft with respect to air
d) moment of aircraft with respect to ground
Answer: a
Clarification: True airspeed is the relative speed of aircraft with respect to the surrounding air flow. As the altitude increases the pressure decreases and the true airspeed is greater than indicated airspeed. It is also represented as TAS.

6. TAS stands for _________
a) true air speed
b) temperature air speed
c) troposphere air speed
d) thermal air speed
Answer: a
Clarification: TAS stands for true air speed. True airspeed is the relative speed of aircraft with respect to the surrounding air flow. As the altitude increases the pressure decreases and the true airspeed is greater than indicated airspeed.

7. IAS stands for ___________
a) inductor air speed
b) indicated air speed
c) induced air speed
d) isentropic air speed
Answer: b
Clarification: IAS stands for indicated air speed. Indicated air speed is the speed indicated on the airspeed indicator in the cockpit. Airspeeds are of four types. They are ground speed, true airspeed, calibrated airspeed and indicated airspeed.

8. GS stands for __________
a) gravitational speed
b) greater speed
c) ground speed
d) gradual speed
Answer: c
Clarification: GS stands for ground speed. Ground speed is the relative movement between the aircraft and the ground. It is corrected for true air speed. For example, 98 knots true air speed + 10 knots tailwind=108 knots ground speed.

9. CAS stands for __________
a) calculated air speed
b) casual air speed
c) crucial air speed
d) calibrated air speed
Answer: d
Clarification: CAS stands for calibrated air speed. Calibrated air speed is the indicated air speed corrected for the instrument and positional errors. Airspeeds are of four types. They are ground speed, true airspeed, calibrated airspeed and indicated airspeed.

10. Which of the following is the correct relationship between R and C_p?
a) R=C_p(frac{gamma-1}{gamma})
b) C_p=R(frac{gamma-1}{gamma})
c) R=C_p(frac{gamma+1}{gamma})
d) C_p=R(frac{gamma}{gamma-1})
Answer: a
Clarification: R=C_p(frac{gamma-1}{gamma}) is the correct relationship between R and C_p where R= characteristic gas constant, γ is the ratio of specific heat at constant pressure to that of specific heat at constant volume and C_p is the specific heat at constant pressure.

11. Which of the following is the correct relationship between γ and C_v?
a) C_v=R(frac{gamma}{gamma-1})
b) C_v=(frac{R}{gamma-1})
c) C_v=(frac{R}{gamma+1})
d) C_v=R(frac{gamma}{gammamp1})
Answer: b
Clarification: C_v=(frac{R}{gamma-1}) is the correct relationship between γ and C_v where R= characteristic gas constant, γ is the ratio of specific heat at constant pressure to that of specific heat at constant volume and C_v is the specific heat at constant volume.

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Aircraft Performance Interview Questions and Answers for Experienced people on “Range and Endurance for Aircraft with Thrust Producing Engines”.

1. What is specific fuel consumption?
a) It is the fuel flow rate per unit distance
b) It is the fuel flow rate per unit thrust
c) It is the fuel flow rate per unit time
d) It is the mass flow rate per unit thrust
Answer: b
Clarification: The specific thrust is defined as the fuel flow rate per unit thrust produced by the aircraft. The units of specific thrust are kg/N hr. The expression for specific fuel consumption is given by C=(frac{Q_f}{F_N}) where Q_f is fuel mass flow and F_N is thrust produced by the aircraft.

2. There are ___________ fuel flow laws.
a) one
b) two
c) three
d) four
Answer: c
Clarification: There are three fuel flow laws. They are:
i. C=C₁, here specific fuel consumption is constant
ii. C=C₂θ^1/2Mⁿ , here it considers temperature and effects of mach number
iii. C=C₃+C₄M and C=C₅+C₆F_N, here the assumptions are taken for empirical fuel flow data.

3. What is the significance of first fuel flow law?
a) Specific fuel consumption is not considered
b) Considers temperature and effects of mach number
c) Assumptions are taken for empirical fuel flow data
d) Specific fuel consumption is constant
Answer: d
Clarification: The significance of first fuel flow law is that the specific fuel consumption is constant. The significance of second fuel flow law is that it considers temperature and effects of mach number. The significance of third fuel flow law is that assumptions are taken for empirical fuel flow data.

4. What is the significance of second fuel flow law?
a) specific fuel consumption is not considered
b) considers temperature and effects of mach number
c) assumptions are taken for empirical fuel flow data
d) specific fuel consumption is constant
Answer: b
Clarification: The significance of first fuel flow law is that the specific fuel consumption is constant. The significance of second fuel flow law is that it considers temperature and effects of mach number. The significance of third fuel flow law is that assumptions are taken for empirical fuel flow data.

5. What is the significance of third fuel flow law?
a) Specific fuel consumption is not considered
b) Considers temperature and effects of mach number
c) Assumptions are taken for empirical fuel flow data
d) Specific fuel consumption is constant
Answer: c
Clarification: The significance of first fuel flow law is that the specific fuel consumption is constant. The significance of second fuel flow law is that it considers temperature and effects of mach number. The significance of third fuel flow law is that assumptions are taken for empirical fuel flow data.

6. The second fuel flow law is used in the turbojet or turbofan.
a) True
b) False
Answer: a
Clarification: The significance of first fuel flow law is that the specific fuel consumption is constant. The significance of second fuel flow law is that it considers temperature and effects of mach number. The significance of third fuel flow law is that assumptions are taken for empirical fuel flow data. The second fuel flow law is used in the turbojet or turbofan. Also it takes in account the temperature and effects of mach number.

7. What is meant by fuel ratio?
a) ratio of initial fuel of aircraft to that of final weight of aircraft
b) ratio of final fuel of aircraft to that of initial weight of aircraft
c) ratio of initial weight of aircraft to that of final weight of aircraft
d) ratio of final weight of aircraft to that of initial weight of aircraft
Answer: c
Clarification: The fuel ratio is the ratio of initial weight of aircraft to that of final weight of aircraft. It is denoted by ω. The equation is given by ω=(frac{W_i}{W_f}) where W_i is initial weight of aircraft and W_f is final weight of aircraft.

8. Which of the following is the correct equation?
a) SAR=(frac{C}{V}frac{L}{D}frac{1}{W})
b) SE=(frac{C}{V}frac{L}{D}frac{1}{W})
c) SAR=(frac{V}{C}frac{L}{D}frac{1}{W})
d) SAR=(frac{1}{C}frac{L}{D}frac{1}{W})
Answer: c
Clarification: The equation for specific air range is given by SAR=(frac{V}{C}frac{L}{D}frac{1}{W}) where V is true airspeed, C is specific fuel consumption, L is lift, W is weight. The significance of first fuel flow law is that the specific fuel consumption is constant.

9. There are two fuel flow laws. They are:
i. C=C₁, here specific fuel consumption is constant
ii. C=C₃+C₄M, here it considers temperature and effects of mach number
a) True
b) False
Answer: b
Clarification: There are three fuel flow laws. They are:
i. C=C₁, here specific fuel consumption is constant
ii. C=C₂θ^1/2Mⁿ , here it considers temperature and effects of mach number
iii. C=C₃+C₄M and C=C₅+C₆F_N, here the assumptions are taken for empirical fuel flow data.

10. What is the fuel ratio of aircraft when initial and final weight are 385560kg and 15560kg?
a) 34.78
b) 24.78
c) 56.76
d) 45.65
Answer: b
Clarification: The answer is 24.78. Given W_i is 385560kg and W_f is 15560kg. From the formula ω=(frac{W_i}{W_f})
On substituting the values ω=(frac{385560}{15560})
ω=24.78.

Aircraft Performance for Interviews,

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

1. Which of the following is the correct formula for speed of sound?
a) (sqrt{gamma RT})
b) (sqrt{pRT})
c) (sqrt{rho Rt})
d) (sqrt{gamma R0T})
Answer: a
Clarification: The correct formula for speed of sound is (sqrt{gamma RT}) where R=characteristic gas constant, T=temperature and γ is the ratio of specific heat at constant pressure to that of specific heat at constant volume.

2. What is the speed of sound in air at an altitude where temperature is 299K?
a) 346.61K
b) 343.61K
c) 71.61 °C
d) 70.61 °C
Answer: a
Clarification: The answer is 346.61K. Given T=299K. We know that R=287J/kg-K, γ for air is 1.4.
From a=(sqrt{gamma RT})
a=(sqrt{1.4*287*299})
a=346.61K.

3. What is the relation between pressure and air speed in isentropic relations?
a) (frac{p_1}{p_2})=(Big{1+frac{gamma-1}{2}(frac{V1}{a1})^2Big}^frac{gamma}{gamma-1})
b) (frac{p_1}{p_2})=(Big{1+frac{gamma+1}{2}(frac{V1}{a1})^2Big}^frac{gamma}{gamma+1})
c) (frac{p_1}{p_2})=(Big{1+frac{gamma+1}{2}(frac{V1}{a1})^2Big}^frac{gamma}{gamma-1})
d) (frac{p_1}{p_2})=(Big{1+frac{gamma-1}{2}(frac{V1}{a1})^2Big}^frac{gamma}{gamma+1})
Answer: a
Clarification: The relation between pressure and air speed in isentropic relations is
(frac{p_1}{p_2})=(Big{1+frac{gamma-1}{2}(frac{V1}{a1})^2Big}^frac{gamma}{gamma-1}) where p₁, p₂ are pressures at two points, V₁=velocity at one point, a₁=speed of sound at point one and γ is the ratio of specific heat at constant pressure to that of specific heat at constant volume.

4. What is the pressure ratio of an aircraft moving in air at a mach number 1?
a) 1.893
b) 1.558
c) 1.444
d) 1.555
Answer: a
Clarification: The answer is 0.458. Given M=1. We know γ of air is 1.4. From (frac{p_1}{p_2}=Big{1+frac{gamma-1}{2}(M)^2Big}^frac{gamma}{gamma-1})
On substituting the values (frac{p_1}{p_2}=Big{1+frac{1.4-1}{2} 1^2Big}^frac{1.4}{1.4-1})
(frac{p_1}{p_2})=1.893.

5. What is the pressure ratio of an aircraft moving in air at a velocity 500m/s and speed of sound is 244 m/s?
a) 4.556
b) 3.327
c) 6.256
d) 2.565
Answer: b
Clarification: The answer is 0.458. Given V=500m/s, a=244m/s. We know γ of air is 1.4. From (frac{p_1}{p_2})=(Big{1+frac{gamma-1}{2}(frac{V1}{a1})^2Big}^frac{gamma}{gamma-1})
On substituting the values (frac{p_1}{p_2}=Big{1+frac{500}{244}Big}^frac{1.4}{1.4-1})
(frac{p_1}{p_2})=3.327.

6. Which of the following is the correct isentropic relation between pressure and temperature?
a) (frac{p_1}{p_2}=(frac{T_2}{T_1})^frac{gamma}{1-gamma})
b) (frac{p_1}{p_2}=(frac{T_2}{T_1})^frac{gamma-1}{gamma})
c) (frac{p_1}{p_2}=(frac{T_2}{T_1})^frac{gamma+1}{gamma})
d) (frac{p_1}{p_2}=(frac{T_2}{T_1})^frac{gamma}{gamma-1})
Answer: a
Clarification: (frac{p_1}{p_2}=(frac{T_2}{T_1})^frac{gamma}{1-gamma}) is the correct isentropic relation between pressure and temperature where p₁, p₂ are pressures, T₁, T₂ are temperatures and γ is the ratio of specific heat at constant pressure to that of specific heat at constant volume.

7. What is the speed of sound where density and pressure are 1.225kg/m³ and 101306N/m²?
a) 340.26m/s
b) 330.26m/s
c) 313 m/s
d) 325 m/s
Answer: a
Clarification: The answer is 340.26m/s. Given P=101306N/m², ρ=1.225kg/m³ and we know that γ for air is 1.4. From the formula, a=(sqrt{frac{gamma P}{rho}})
a=(sqrt{frac{gamma*101306}{1.225}})
a=340.26m/s.

8. What is the formula for speed of sound in terms of pressure and density?
a) a=(sqrt{frac{gamma P}{rho}})
b) a=(sqrt{frac{gammarho}{P}})
c) a=(sqrt{frac{gamma RP}{rho}})
d) a=(sqrt{frac{gamma P}{rho R}})
Answer: a
Clarification: The formula for speed of sound in terms of pressure and density is given by a=(sqrt{frac{gamma P}{rho}}) where a=speed of sound, P=pressure, ρ=density and γ is the ratio of specific heat at constant pressure to that of specific heat at constant volume.

9. What is the relation between equivalent air speed and pressure ratio?
a) V_e=V(sqrt{sigma})
b) V_e=(frac{V}{sqrt{sigma}})
c) V_e=Vσ²
d) V_e=Vσ^-2
Answer: a
Clarification: V_e=V(sqrt{sigma}) is the relation between equivalent air speed and pressure ratio where V_e is the equivalent air speed, V=velocity and σ is pressure ratio.

10. What is the equivalent air speed where velocity is 330m/s and pressure ratio is 8.447?
a) 959.1m/s
b) 1000m/s
c) 981m/s
d) 954m/s
Answer: a
Clarification: The answer is 959.1m/s. Given V=330m/s, σ=8.447. From the equation V_e=V(sqrt{sigma})
V_e=330(sqrt{8.447})
V_e=959.1m/s.

11. What is equivalent air speed?
a) The calibrated air speed corrected for scale-altitude error
b) The true air speed corrected for scale-altitude error
c) The indicated air speed corrected for scale-altitude error
d) The ground air speed corrected for scale-altitude error
Answer: a
Clarification: Equivalent air speed is the calibrated air speed corrected for scale-altitude error. The correction is done in calibrated equation of the airspeed indicator which is a function of calibrated air speed and height.

12. Which of the following is the full-law calibration equation?
a) p_p-p=p₀(Bigg[Big{1+frac{gamma-1}{2}left(frac{V_c}{a_0}right)^2Big}^{frac{gamma}{gamma-1}}-1Bigg])
b) p_p-p=p₀(Bigg[Big{1+frac{gamma+1}{2}left(frac{V_c}{a_0}right)^2Big}^{frac{gamma}{gamma-1}}-1Bigg])
c) p-p₀=p₀(Bigg[Big{1+frac{gamma-1}{2}left(frac{V_c}{a_0}right)^2Big}^{frac{gamma}{gamma-1}}-1Bigg])
d) p_p-p=p₀(Bigg[Big{1+frac{gamma-1}{2}left(frac{V_c}{a_0}right)^2Big}^{frac{gamma}{gamma+1}}-1Bigg])
Answer: a
Clarification: The full-law calibration equation is p_p-p=p₀(Bigg[Big{1+frac{gamma-1}{2}left(frac{V_c}{a_0}right)^2Big}^{frac{gamma}{gamma-1}}-1Bigg]) where p_p, p, p₀ are pressures, V_c is calibrated air speed and a₀ is speed of sound and γ is the ratio of specific heat at constant pressure to that of specific heat at constant volume.

Aircraft Performance Multiple Choice Questions on “Cruise Method 1 – 1”.

1. In cruise method 1 the air pressure is decreased whereas the aircraft weight is increased.
a) True
b) False
Answer: b
Clarification: In cruise method 1 the air pressure is decreased as well as the aircraft weight is decreased. In cruise method 1 the W/p ratio is maintained constant and also L/D ratio is also kept constant.

2. What is the condition of cruise method 1?
a) Air pressure is increased
b) Aircraft weight is increased
c) W/D ratio is kept constant
d) L/D ratio is varying
Answer: c
Clarification: In cruise method 1 the air pressure is decreased as well as the aircraft weight is decreased. In cruise method 1 the W/p ratio is maintained constant and also L/D ratio is also kept constant.

3. Cruise climb technique is involved in ___________
a) cruise method 1
b) cruise method 2
c) cruise method 3
d) cruise method 4
Answer: a
Clarification: Cruise climb technique is involved in cruise method 1. In cruise method 1 the air pressure is decreased as well as the aircraft weight is decreased. In cruise method 1 the W/p ratio is maintained constant and also L/D ratio is also kept constant.

4. Which of the following is incorrect statement regarding cruise method 1?
a) W/D ratio is kept constant
b) L/D ratio is varying
c) Air pressure is decreased
d) Aircraft weight is decreased
Answer: d
Clarification: In cruise method 1 the air pressure is decreased as well as the aircraft weight is decreased. In cruise method 1 the W/p ratio is maintained constant and also L/D ratio is also kept constant.

5. What is Brequet Range expression?
a) R₁ = (frac{D}{C}frac{L}{V}) l_n ω
b) R₁ = (frac{1}{C} left[frac{2W}{rho S}right]^{frac{1}{2}} frac{C_L^{frac{1}{2}}}{C_D}) l_n ω
c) R₁ = (frac{1}{V} left[frac{2W}{rho S}right]^{frac{1}{2}} frac{C_L^{frac{1}{2}}}{C_D}) l_n ω
d) R₁ = (frac{V}{C}frac{L}{D}) l_n ω
Answer: d
Clarification: Brequet Range expression is given by R₁ = (frac{V}{C}frac{L}{D}) l_n ω where V is true airspeed, C is specific fuel consumption, L is lift, D is drag, and ω is fuel ratio. This Brequet Range expression comes in the cruise method 1.

6. Brequet Range expression value is maximum at __________
a) 1.316 V_md
b) 1.216 V_md
c) 1.3 V_md
d) 1.2 V_md
Answer: a
Clarification: Brequet Range expression is given by R₁ = (frac{V}{C}frac{L}{D}) l_n ω where V is true airspeed, C is specific fuel consumption, L is lift, D is drag, and ω is fuel ratio. This Brequet Range expression comes in the cruise method 1. Brequet Range expression value is maximum at 1.316 V_md.

7. What is range factor in cruise method 1?
a) (left[frac{V_{mdi}}{C} E_{max}right])
b) (left[frac{V_{max}}{C} E_{max}right])
c) (Big{frac{2u^3}{u^4+1}Big})
d) (Big{frac{2u^4}{u^4+1}Big})
Answer: a
Clarification: Range factor in cruise method 1 is given by (left[frac{V_{mdi}}{C} E_{max}right]). The range equation in cruise method 1 is given by R₁ = (left[frac{V_{mdi}}{C} E_{max}right]Big{frac{2u^3}{u^4+1}Big}) l_n ω where V is true airspeed, C is specific fuel consumption, L is lift, D is drag, E_max is endurance and ω is fuel ratio.

8. Which of the following does range factor consists?
a) Air density
b) Cruise weight
c) Temperature
d) Cruise weight and air density
Answer: d
Clarification: Range factor consists of cruise weight and air density. Range factor in cruise method 1 is given by (left[frac{V_{mdi}}{C} E_{max}right]). The range equation in cruise method 1 is given by R₁=(left[frac{V_{mdi}}{C} E_{max}right]Big{frac{2u^3}{u^4+1}Big}) l_n ω where V is true airspeed, C is specific fuel consumption, L is lift, D is drag, E_max is endurance, u is relative airspeed and ω is fuel ratio.

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Aircraft Performance Questions and Answers for Entrance exams on “Effect of Wind on Climb Performance and Descent Performance”.

1. Wind is the relative velocity between the air mass and the ground.
a) True
b) False
Answer: a
Clarification: Wind is the relative velocity between the air mass and the ground. Usually wind is assumed to have only a horizontal component but there exists vertical component which may affect the aircraft at considerable height.

2. The aircraft is taken to the level ground operating for ________
a) considering vertical component of the wind
b) considering horizontal component of the wind
c) considering both horizontal and vertical component of the wind
d) neglecting the effect of wind
Answer: b
Clarification: The aircraft is taken to the level ground operating for considering horizontal component of the wind. Wind is the relative velocity between the air mass and the ground. Usually wind is assumed to have only a horizontal component but there exists vertical component which may affect the aircraft at considerable height.

3. The relative velocity of the wind produces boundary layer close to the ground which ___________
a) decreases the wind speed with decrease in height
b) increases the wind speed with decrease in height
c) makes the wind speed unaffected
d) constantly increases
Answer: a
Clarification: The relative velocity of the wind produces boundary layer close to the ground which decreases the wind speed with decrease in height. This will further produce effects on the aircraft.

4. The flight path is calculated relative to ________
a) air mass
b) still air condition
c) air mass and still air condition
d) airspeed
Answer: a
Clarification: The flight path is calculated relative to air mass. This resulted in the development of the theory by experimenting in the still air condition. In actual performance of the aircraft the relative velocity is not effected by the reference axis as they are velocity axes.

5. It is assumed zero velocity datum at the aerodynamic center of the aircraft.
a) True
b) False
Answer: b
Clarification: It is assumed zero velocity datum at the center of gravity (CG) of the aircraft. Centre of gravity (CG) of an aircraft is the point at which the whole weight of the aircraft is being balanced. This CG does not change with respect to speed of the aircraft.

6. The performance relative to ground is effected by the wind.
a) True
b) False
Answer: b
Clarification: The performance relative to ground is effected by the wind. The relative velocity of the wind produces boundary layer close to the ground which decreases the wind speed with decrease in height. This will further produce effects on the aircraft.

7. What is meant by perceived performance?
a) Visualization of the aircraft with respect to wind
b) Visualization of the aircraft with respect to aircraft relative to ground
c) Visualization of the aircraft with respect to wind with respect to ground
d) Visualization of the aircraft with respect to any one frame such as aircraft or ground
Answer: d
Clarification: Visualization of the aircraft with respect to any one frame such as aircraft or ground is known as the perceived performance. This effects the ability of the aircraft to clear ground-based obstructions.

8. The rate of climb or descent relative to air mass is unaffected by the tailwind.
a) True
b) False
Answer: b
Clarification: The rate of climb or descent relative to air mass is unaffected by the wind but the horizontal component of true airspeed is effected by the tailwind. The effect is increased by tailwind and decreased by the headwind.

9. The horizontal component of the true airspeed is _______________
a) increased by tailwind
b) decreased by tailwind
c) increased by headwind
d) unaffected by the airspeed
Answer: a
Clarification: The rate of climb or descent relative to air mass is unaffected by the wind but the horizontal component of true airspeed is effected by the tailwind. The effect is increased by tailwind and decreased by the headwind.

10. What is wind shear?
a) The extreme case of airspeed effect on the aircraft
b) The extreme case of wind effect on the aircraft
c) The extreme case of temperature effect on the wind
d) The extreme case of altitude effect on the wind
Answer: b
Clarification: The extreme case of wind effect on the aircraft is known as the wind shear. In this case the rate of change of the wind speed is very high. This effect is caused by the meteorological conditions.

Aircraft Performance for Entrance exams,