Pressure and Density Height

Question 1

What is the International Standard Atmosphere (ISA) temp and pressure at sea level?

Answer 1

+15 degrees C

1013 hPa

Question 2

In ISA conditions what is the temp drop in height increase?

What is the pressure drop in height?

Answer 2

2 degrees C / 1000ft

1 hPa / 30ft of height gained

Question 3

What is the ISA temp at 6000’?
What is the ISA temp at 1000’?
What is the ISA temp at 5000’?
What is the ISA temp at 12000’?

Answer 3

+15 - (2x6) ANS = 3 degrees C
+15 - (2x1) ANS = 13 degrees C
+15 - (2x5) ANS = 5 degrees C
+15 - (2x12) ANS = -9 degrees C

Question 4

If the outside air temp at 4000’ is +12 degrees C, how much hotter is it from ISA

Answer 4

ANS = 5 degrees C hotter than ISA

Question 5

Find the ISA deviation in the following:
Pressure Height. Outside Air Temp.
4500’ 12 degrees C

Answer 5

Ans = 15 - (2x4.5) = +6 (ISA)
OAT = 12 degrees C
therefore ISA deviation = +6

Question 6

Pressure Height. Outside Air Temp.
13000’ 0 degrees C

Answer 6

Ans = 15 - (2x13) = -11 (ISA)
OAT = 0 degrees C
therefore ISA deviation = +11

Question 7

Pressure Height. Outside Air Temp. 8500’ 12 degrees C

Answer 7

Ans = 15 - (2x8.5) = -2 (ISA)
OAT = 12 degrees C
therefore ISA deviation = +14

Question 8

Pressure Height. Outside Air Temp.

4) 21000’ -15 degrees C
5) 4500’ -4 degrees C

Answer 8

Ans = 15 - (2x21) = -27 (ISA)
OAT = -15 degrees C
therefore ISA deviation = +12

Question 9

Pressure Height. Outside Air Temp.
4500’ -4 degrees C

Answer 9

Ans = 15 - (2x4.5) = 6 (ISA)
OAT = -4 degrees C
therefore ISA deviation = -10

Question 10

Using a flight computer how do you calculate the density height.

Answer 10

Ans: set the given pressure height against the temp. Read the density height from the density height window.

Question 11

To calculate the density height, what are the factors that are required?

Answer 11

Ans: QNH, elevation and Temperature.

Question 12

What is the calculation to obtain pressure height?

Answer 12

1013 - QNH x 30 + elevation = Pressure Height

Question 13

Where would you find the declared density height graph

Answer 13

Ans: VFRG

Question 14

If the strip elevation is 2100ft and the QNH is 1002, what is the pressure height?

Answer 14

Pressure Height = 2430ft

Question 15

If the strip elevation is 850ft and the QNH is 1028, what is the pressure height?

Answer 15

Pressure Height = 400ft

Question 16

If the strip elevation is 210ft and the QNH is 1030, what is the pressure height?

Answer 16

Pressure Height = 2430ft

Question 17

If the strip elevation is 3150ft and the QNH is 993, what is the pressure height?

Answer 17

Pressure Height = -300ft

Question 18

If the strip elevation is at sea level and the QNH is 1025, what is the pressure height?

Answer 18

Pressure Height = 3750ft

Question 19

Formula for calculating Pressure height

Answer 19

Elevation + (1013 - QNH) x 30 = Pressure Height