GATE AE Atmosphere & Flight Instruments: Previous Year Questions

GATE AE 2025, Question 24 (1 mark, MCQ)

Flight Mechanics & Space Dynamics - Atmosphere & Flight Instruments

A general aviation airplane is flying at an altitude of 5000 m. The indicated airspeed is 250 km/h. Assume that there are no instrument errors and position errors. Neglecting compressibility effects, which one of the following options is FALSE?

1. The true airspeed is greater than 250 km/h.
2. The calibrated airspeed is 250 km/h.
3. The true airspeed is 250 km/h.
4. The equivalent airspeed is 250 km/h.

Official answer: C

GATE AE 2024, Question 38 (2 marks, MCQ)

Flight Mechanics & Space Dynamics - Atmosphere & Flight Instruments

As per the International Standard Atmosphere model, which one of the following options about density variation with increase in altitude in the isothermal layer is correct?

1. remains constant
2. increases linearly
3. decreases linearly
4. decreases exponentially

Official answer: D

GATE AE 2024, Question 61 (2 marks, NAT)

Flight Mechanics & Space Dynamics - Atmosphere & Flight Instruments

For an aircraft moving at 4 km altitude above mean sea level at a Mach number of 0.2, the ratio of equivalent air speed to true air speed is _______ (rounded off to 2 decimal places). The density of air at mean sea level is 1.225 kg/m$^3$ and at 4 km altitude is 0.819 kg/m$^3$.

Official answer: 0.80 to 0.84

GATE AE 2023, Question 34 (1 mark, NAT)

Flight Mechanics & Space Dynamics - Atmosphere & Flight Instruments

Airplane A and Airplane B are cruising at altitudes of 2 km and 4 km, respectively. The free stream density and static pressure at altitude 2 km are 1.01 kg/m$^3$ and 79.50 kPa, respectively, and at altitude 4 km, they are 0.82 kg/m$^3$ and 61.70 kPa, respectively. The differential pressure reading from the pitot-static tubes is 3 kPa for both the airplanes. Assuming incompressible flow, the ratio of cruise speeds of Airplane A to Airplane B is ______. (round off to two decimal places)

Official answer: 0.89 to 0.91

GATE AE 2023, Question 45 (2 marks, MSQ)

Flight Mechanics & Space Dynamics - Atmosphere & Flight Instruments

Consider the International Standard Atmosphere (ISA) with $h$ being the geopotential altitude (in km) and $\dfrac{dT}{dh}$ being the temperature gradient (in K/m). Which of the following combination(s) of $\left(h, \dfrac{dT}{dh}\right)$ is/are as per ISA?

1. $(7,\ -6.5 \times 10^{-3})$
2. $(9,\ 4 \times 10^{-3})$
3. $(15,\ 0)$
4. $(35,\ 3 \times 10^{-3})$

Official answer: A, C, D

GATE AE 2022, Question 27 (1 mark, MSQ)

Flight Mechanics & Space Dynamics - Atmosphere & Flight Instruments

For International Standard Atmosphere (ISA) up to 11 km, which of the following statement(s) is/are true?

1. The hydrostatic/ aerostatic equation is used
2. The temperature lapse rate is taken as $-10^{-2}$ K/m
3. The sea level conditions are taken as: pressure, $p_s = 1.01325 \times 10^5$ Pa; temperature, $T_s = 300$ K; density, $\rho_s = 1.225$ kg/m$^3$
4. Air is treated as a perfect gas

Official answer: A, D

GATE AE 2018, Question 48 (2 marks, NAT)

Flight Mechanics & Space Dynamics - Atmosphere & Flight Instruments

Assuming ISA standard sea level conditions (288.16 K, density 1.225 kg/m$^3$, $g = 9.81$ m/s$^2$, $R = 287$ J/(kg-K)), the density (in kg/m$^3$) of air at Leh, which is at an altitude of 3500 m above mean sea level is ________ (accurate to two decimal places).

Official answer: 0.85 to 0.88

GATE AE 2018, Question 52 (2 marks, NAT)

Flight Mechanics & Space Dynamics - Atmosphere & Flight Instruments

An aircraft with a gross weight of 2000 kg, has a speed of 130 m/s at sea level, where the conditions are: 1 atmosphere (pressure), 288 K (temperature), and 1.23 kg/m$^3$ (density). The speed (in m/s) required by the aircraft at an altitude of 9000 m, where the conditions are: 0.31 atmosphere, 230 K, and 0.47 kg/m$^3$, to maintain a steady, level flight is ________ (accurate to two decimal places).

Official answer: 209.00 to 211.00

GATE AE 2018, Question 53 (2 marks, NAT)

Flight Mechanics & Space Dynamics - Atmosphere & Flight Instruments

A pitot probe on an aircraft in a steady, level flight records a pressure of 55,000 N/m$^2$. The static pressure and density are 45,280 N/m$^2$ and 0.6 kg/m$^3$, respectively. The wing area and the lift coefficient are 16 m$^2$ and 2, respectively. The wing loading (in N/m$^2$) on this aircraft is _________ (accurate to one decimal place).

Official answer: 18000 to 19440

GATE AE 2016, Question 32 (1 mark, MCQ)

Flight Mechanics & Space Dynamics - Atmosphere & Flight Instruments

During an aircraft cruising flight, the altitude above the ground is usually measured using

1. dynamic pressure.
2. static pressure.
3. radar.
4. laser range finder.

Official answer: B

GATE AE 2016, Question 33 (1 mark, MCQ)

Flight Mechanics & Space Dynamics - Atmosphere & Flight Instruments

Indicated airspeed is used by a pilot during

1. take-off.
2. navigation.
3. setting the engine RPM.
4. setting the elevator angle.

Official answer: A

GATE AE 2014, Question 32 (1 mark, MCQ)

Flight Mechanics & Space Dynamics - Atmosphere & Flight Instruments

The vertical ground load factor on a stationary aircraft parked in its hangar is:

1. 0
2. -1
3. Not defined
4. 1

Official answer: D