FAA Private Pilot Airplane (PAR)Weather Theory and ServicesHard
An airport has a field elevation of 1,500 feet MSL. The current altimeter setting is 30.42 inches of mercury. What is the pressure altitude at this airport?
- A1,000 feet
- B1,500 feet
- C2,000 feet
- D500 feet
Show answer & explanationAnswer & explanation
Correct answer: A. 1,000 feet
Pressure altitude is found by applying a correction of 1,000 feet for every 1.00 inch of Hg the altimeter setting differs from the standard 29.92. Here, 30.42 - 29.92 = 0.50 inch, which corresponds to 500 feet. Since the setting is higher than standard, subtract: 1,500 - 500 = 1,000 feet pressure altitude.
Why the other options are wrong
- B. This ignores the altimeter setting correction entirely.
- C. This results from adding rather than subtracting the correction for a high altimeter setting.
- D. This would result from subtracting 1,000 feet instead of 500 feet.
Pressure Altitude Calculation
Pressure altitude is the altitude indicated when the altimeter is set to 29.92 inches of Hg; it is found by correcting field elevation using the difference between the current altimeter setting and 29.92.
- Each 0.10 inch of Hg difference from 29.92 equals about 100 feet of altitude
- If setting is above 29.92, subtract the correction from field elevation
- If setting is below 29.92, add the correction to field elevation
Memory trick: 'High is a Lie, Subtract to Comply' — high altimeter setting means subtract the correction.