MACHMETER – Air – DGCA Question Bank For Politics

#1. The local speed of sound is equal to: (K = Constant)

K √ temperature (°F) knots

K √ temperature (°K) knots

K √ temperature (°C. knots

K √ temperature (°K) metres per second

#2. At FL 350 with a JSA deviation of -12, the true airspeed when flying at M 0.78 is

460 kt

436 kt

447 kt

490 kt

#3. Below is a schematic diagram of a Machmeter. Parts A, B, C and D are:

ratio arm, mach no pointer, static pressure inlet, ranging arm.

ranging arm, limiting mach no index, static pressure inlet, ratio arm.

main shaft, TAS index, pitot pressure inlet, ranging arm.

ranging arm, limiting mach no index, pitot inlet, main shaft.

#4. When climbing at a constant mach number below the tropopause through an inversion:

the CAS and TAS will both increase.

the CAS and TAS will both decrease.

the CAS will decrease and the TAS will increase.

the CAS will increase and the TAS will decrease.

#5. When descending below the tropopause under normal conditions (increasing temperature) at a constant CAS:

both TAS and mach number will decrease.

both TAS and mach number will increase.

the TAS will decrease and the mach number will increase.

the TAS will increase and the mach number will decrease.

#6. Cruising at FL390, M 0.84 is found to give a TAS of 499 kt. The ISA deviation at this level will be:

-17

+17

+19

-19

#7. The errors to which the machmeter is subject are:

instrument error, position error, compressibility error and manoeuvre induced error.

instrument error, position error and manoeuvre induced error.

instrument error, position error, barometric error, temperature error and manoeuvre induced error.

instrument error, position error, density error and manoeuvre induced error.

#8. The relationships between TAS, mach number (MNo) and local speed of sound (LSS) is:

LSS = MNo / TAS

MNo = LSS / TAS

TAS = MNo x LSS

MNo = LSS x TAS

#9. The machmeter gives an indication of mach number by measuring the ratio:

pitot pressure / static pressure

static pressure / dynamic pressure

dynamic pressure / pitot pressure

dynamic pressure/ static pressure

#10. An aircraft is flying at FL350 with a JSA deviation of +8. The mach no is 0.83 and the TAS 485. If the aircraft descends to FL300 and maintains the same mach no and TAS, the JSA deviation will now be:

+8

-2

+2

-18

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