FAA Aircraft Dispatcher (ADX)Flight Planning and PerformanceEasy
A Part 121 turbojet aircraft is scheduled to depart from an airport where the published field elevation is 1,500 feet MSL. The current altimeter setting is reported as 29.82 inHg. What is the pressure altitude at this airport?
- A1,300 feet MSL
- B1,650 feet MSL
- C1,500 feet MSL
- D1,700 feet MSL
Show answer & explanationAnswer & explanation
Correct answer: D. 1,700 feet MSL
Pressure altitude is calculated by adjusting the field elevation for variations in altimeter setting from the standard 29.92 inHg. For every 0.01 inHg below 29.92, add 10 feet to the field elevation.
Why the other options are wrong
- A. This would be correct if the altimeter setting was significantly higher than standard, not lower.
- B. This calculation does not correctly apply the altimeter setting correction factor.
- C. This is the field elevation, not the pressure altitude. Pressure altitude only equals field elevation when the altimeter setting is 29.92 inHg.
Pressure Altitude
Pressure altitude is the altitude in the International Standard Atmosphere (ISA) corresponding to a given static pressure. It is used in aircraft performance calculations.
- It is expressed in feet above the standard datum plane.
- Used for aircraft performance calculations, especially takeoff and landing.
- Calculated by adjusting field elevation for non-standard altimeter settings.
Memory trick: PA: Picture Altitude, Adjust!