Chapter 5.5 - Pressure, Temperature and Density Flashcards
What are the main elements to Air Density?
- Temperature.
- Pressure.
What does ISA stand for?
International Standard Atmosphere.
A decrease in pressure causes an (increase/decrease) to density?
Decrease.
A decrease in temperature causes an (increase/decrease) in density?
Increase.
Density (increases/decreases) with Height?
Decreases.
Which rate of decrease is higher with Height (Temperature/Pressure)?
Pressure.
What is the ISA MSL Pressure?
1013 hPa.
What is the ISA MSL Temperature?
+15°C.
What is the ISA Pressure Lapse Rate (2)?
- 30 feet is 1 hPa.
- 1000 feet is 30 hPa.
What is the ISA Temperature Lapse Rate?
-2°C for every 1000 feet.
What does PH stand for?
Pressure Height.
Define PH?
The Height above sea level in the ISA.
How does a Pilot find the Pressure Height using the Altimeter?
By setting 1013 hPa in the pressure-setting datum.
True or False. If the pressure is higher than 1013 hPa, the calculation is to increase the difference?
False. Decrease.
True or False. If the pressure is lower than 1013 hPa, the calculation is to increase the difference?
True.
If an Aircraft is at 3000 feet with the pressure-setting datum set at 1003 hPa. What would be the Pressure Height?
3300 feet.
If an Aircraft is at 3000 feet with the pressure-setting datum set at 1023 hPa. What would be the Pressure Height?
2700 feet.
How can the Pressure Height be calculated without the use of an Altimeter (2)?
- QNH.
- Altitude/Elevation.
How can QNH be obtained (2)?
- Aerodrome Forecast (TAF).
- Area Forecast (ARFOR).
How can a Pilot find Temperature in the Cockpit?
Outside Air Temperature gauge (OAT).
How can a Pilot find Temperature outside the Cockpit (2)?
- Aerodrome Forecast (TAF).
- Area Forecast (ARFOR).
How do you convert °C to °F (3)?
- Divide °C by 5.
- Multiple this by 9.
- Add 32.
How do you convert °F to °C (3)?
- Subtract 32 from °F.
- Multiple this by 5.
- Divide this by 9.
What does DH stand for?
Density Height.
Define DH?
The Pressure Height corrected for any difference between actual and ISA Temperature at that particular Pressure Height.
When the atmosphere is warmer than the ISA, the Density Height will be (greater/lower) than the Pressure Height?
Greater.
When the atmosphere is cooler than the ISA, the Density Height will be (greater/lower) than the Pressure Height?
Lower.
Name three types of Atmospheric Conditions of Temperature, Pressure and Wind?
- Ambient Conditions.
- Forecast Conditions.
- Declared Conditions.
What is meant by Ambient Condition?
The atmospheric conditions of Temperature, Pressure and Wind that apply to the air surrounding the Aircraft.
What is meant by Declared Condition?
The atmospheric conditions of Temperature, Pressure and Wind declared by authorities.
When must a Pilot convert to Density Height with regards to ISA Pressure?
+/- 8 hPa (1005 and 1021 hPa).
When must a Pilot convert to Density Height with regards to ISA Temperature?
+/- 2°C.
True of False. Density Height should be used to calculate Climb/Descent Heights?
False. Pressure Height should always be used.
If QNH is between 1005 and 1020P hPa. What should be used as Height?
Elevation, Altitude or Pressure Height.
If QNH is above 1020 hPa. What should be done to the Pressure Height?
Pressure Height = Elevation/Altitude – 500 feet.
If QNH is below 1005 hPa. What should be done to the Pressure Height?
Pressure Height = Elevation/Altitude + 500 feet.
