Pressure Altitude From QNH Calculator
Convert an indicated altitude and QNH into pressure altitude at 27 feet per hectopascal.
Description
Convert an indicated altitude and QNH into pressure altitude at 27 feet per hectopascal.
Pressure Altitude From QNH Calculator provides a focused, reproducible calculation with explicit inputs and a deterministic result. Convert an indicated altitude and QNH into pressure altitude at 27 feet per hectopascal.
Use for a quick linear pressure-altitude estimate from indicated altitude and QNH.
When to use Pressure Altitude From QNH Calculator
Use for a quick linear pressure-altitude estimate from indicated altitude and QNH.1
How the calculation works
Convert an indicated altitude and QNH into pressure altitude at 27 feet per hectopascal.2
Pressure altitude ≈ indicated altitude + (1013.25 − QNH) × 27 ft/hPa Inputs and interpretation
Keep every input on the same valuation, timing, unit, and assumption basis. Interpret the output at the precision supported by those inputs rather than treating extra decimal places as additional certainty.
Limitations and assumptions
The 27 ft/hPa factor is an approximation; use the altimeter set to standard pressure or approved calculation where precision affects performance.
References
-
Pilot's Handbook of Aeronautical Knowledge — Federal Aviation Administration
-
International Standard Atmosphere — Wikipedia contributors
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