FAA Flight Instructor Airplane (FIA)Performance, Weight and BalanceMedium
An airport has a field elevation of 3,000 ft. The current altimeter setting is 30.42 inches of mercury. What is the approximate pressure altitude at the field?
- A2,950 ft
- B2,500 ft
- C3,050 ft
- D3,500 ft
Show answer & explanationAnswer & explanation
Correct answer: B. 2,500 ft
Pressure altitude = field elevation + (29.92 − altimeter setting) × 1,000. Here: 3,000 + (29.92 − 30.42) × 1,000 = 3,000 − 500 = 2,500 ft.
Why the other options are wrong
- A. This applies only a partial correction of about 50 ft, not the full 500 ft.
- C. This adds the correction instead of subtracting it for a high altimeter setting.
- D. This overcorrects by adding 500 ft instead of subtracting it.
Pressure Altitude Calculation
Pressure altitude is the altitude indicated when the altimeter is set to 29.92 inHg; it is found by correcting field elevation for the difference between the current setting and standard pressure.
- PA = field elevation + (29.92 − altimeter setting) × 1,000
- High altimeter setting subtracts from elevation
- Low altimeter setting adds to elevation
Memory trick: High is Low — high altimeter setting lowers pressure altitude