Air Data Instruments

Question 1

Formula for Mach number

Answer 1

MACH= TAS/ LSS

Question 2

Formula for LSS

Answer 2

LSS= 38.94√K

K is temperature of Static air temperature.
Always calculate temperature to degrees Kelvin first, °C+273= A°

Question 3

Temperature Equation

Answer 3

Ts= Tm÷(1+(0.2×k×M^2))

*Use this formula if ever given the TAT

Question 4

ADC- air data computer

Answer 4

Normally at least two ADC units, one for the pilot and one for the copilot

Question 5

Calculate wind direction / speed vector

Answer 5

Once you have heading/TAS Vector (from ADC and whichever sensor that provides heading data) , and TRK/GS Vector (from GPS/ INS), a simple Vector calculation will provide wind direction

Question 6

Machmeter

Answer 6

Instrument showing the ratio of True Air Speed to the local speed of sound as a decimal number

Question 7

Temperature to LSS and Mach relationship

Answer 7

Reduction in temperature reduces local speed of sound. As local speed of sound is inversely proportional to Mac number, Mac number increases.

Question 8

Air Data Computer

Answer 8

A computer that receives Pitot pressure, static pressure, temperature and angle of attack.

Question 9

Errors of the Machmeter

Answer 9

Instrument . POSITION. Lag

Question 10

Blockages and leakages Machmeter

Answer 10

COPS DUO.

THREE SEPARATE STATIC AND PITOT PORTS IN AIRBUS A320.

Question 11

Temperature vs Mach number

Answer 11

Decrease in temperature will increase the Mach number.

Increase in temperature will decrease the Mach number

Question 12

Altitude vs Mach number

Answer 12

Increasing altitude, temperature decreases, LSS decreases, which increases Mach number

With increase in altitude, a density decreases, increasing TAS which also increases Mach number

Question 13

Constant MACH relationship to TAS and LSS

Answer 13

FL250 M0.8 LSS 500 TAS 400

CLIMBING TO FL300
M0.8 LSS 400 TAS 320

LSS has reduced with an increase in altitude, TAS has also reduced to maintain a constant MACH number

Question 14

ISA

Answer 14

Lapse rate -1.98/1000’ to 36,090’. -56.5°C… 216.5 A°

Jet Standard Atmosphere NO TROPOPAUSE

Question 15

Air Data Computer

Answer 15

Three inputs:
1. Pitot pressure
2. Static pressure,
3. Total air temperature.
Redundancies: 2 ADCs, interlinked separate systems, one for the pilot and one for the co-pilot.

Question 16

Stagnation Temperature

Answer 16

INDICATED OUTSIDE AIR TEMPERATURE, IOAT, or TOTAL AIR TEMPERATURE, TAT .

Question 17

Flush Bulb Probe

Answer 17

Recovery factor between 70% and 90%, 0.7 and 0.9 RF.

Question 18

TAT PROBE recovery factor

Answer 18

Recovery factor of 100%, 1.

Question 19

TAT PROBE function

Answer 19

Ramrise calculated using aircraft’s current speed. Mounted on the side of the aircraft’s nose.

Sensing element is made of pure PLATINUM, a metal that has an electrical resistance very sensitive to temperature changes.