Atmosphere and Altimetry

Question 1

What is ISA? Define it

Answer 1

International Standard Atmosphere

Pressure= 1013.25 hPa (29.92 inHg) Density = 1.225 kg/m^3 Temperature= +15 degrees celsius

Question 2

In the troposphere, what is the temperature lapse rate (simple)?

Answer 2

A drop of: 2 degrees celsius per 1000FT

Question 3

Pressure reduces at what rate?

Answer 3

1 hPa per 30FT increase in height (approx, up to 5000FT)

Question 4

What effect does absolute temperature have on air density?

Answer 4

Increase in temperature = decrease in density and so on.

INVERSELY PROPORTIONAL

Question 5

What effect does pressure have on density?

Answer 5

Increase in Pressure = Increase in density

DIRECTLY PROPORTIONAL

Question 6

What is the density of water vapour under ISA conditions?

Answer 6

0.766 kg/m^3

Question 7

What effect does an increase in humidity have on density?

Answer 7

It will decrease density as the density of water vapour is less than air.

Question 8

Hot, High, and Humid conditions will___ the density.

a) Increase
b) Reduce
c) Not affect
d) Chickens

Answer 8

b) Reduce

Question 9

Define dynamic pressure (and equation)

Answer 9

1. Created due to motion of air, therefore: dynamic pressure (q) = (1/2)pV(TAS)^2

Question 10

What error must be accounted for from IAS to CAS? Are they present in the CT4B?

Answer 10

Instrument and pressure corrections. Not required in CT4B

Question 11

What correction must be made from CAS to get EAS? Is it made in the CT4B?

Answer 11

Compressibility correction. Not required in the CT4 due to operating speeds and height range.

Question 12

What correction must be made to convert EAS to TAS? Is this correction made in the CT4?

Answer 12

Density correction. This does affect the CT4 so to convert IAS (IAS=EAS in CT4) to TAS you must take into account the density altitude.