Pressure altitude

Pressure altitude: height above the standard-pressure datum, the 29.92" level.

• Altitude read with altimeter set to 29.92" = height that pressure has in the ISA (FAA AWH 8.4.1.4).
• Set 29.92" in Kollsman window: altimeter reads it directly.
• Performance charts drawn against it.
• Station pressure, SLP and QNH: see sea-level-pressure-reduction.

Koch chart, on the ground (TP 1102):

1. Set altimeter to 29.92".
2. Read altitude.
3. Reset altimeter to actual setting.

Trap: pressure altitude is an altitude, not a pressure.

Practice