THE MACHMETER

Question 1

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

Answer 1

b. K √ temperature (K) knots

Question 2

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

Answer 2

b. 436 kt

Question 3

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

Answer 3

c. the CAS will decrease and the TAS will increase.

Question 4

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

Answer 4

a. both TAS and mach number will decrease.

Question 5

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

Answer 5

b. +17

Question 6

6. The errors to which the machmeter is subject are:

Answer 6

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

Question 7

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

Answer 7

c. TAS = MNo x LSS

Question 8

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

Answer 8

d. dynamic pressure/static pressure

Question 9

9. 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:

Answer 9

b. -2