Altimeter serviceability check
Pre-flight ground check (TC AIM AIR 1.5.1):
- Set aerodrome's current altimeter setting on subscale.
- Compare indicated reading to known aerodrome or runway elevation.
- Tolerance: within ±50 feet of known elevation.
- Out of tolerance: beyond ±50 feet: maintenance must check it (TC AIM AIR 1.5.1, referencing 1.5.2). Don't fly it and mentally correct.
Two different limits:
| Limit | Value | Applies to | Cite |
|---|---|---|---|
| Ground check | ±50 feet | Pilot, vs known elevation | TC AIM AIR 1.5.1 |
| Calibration tolerance | ±20 feet at sea level, widens with altitude | Maintenance calibration | TC AIM AIR 1.5.2 |
Trap: ±50 ft is the pilot's ground-check limit; ±20 ft is maintenance calibration. Don't swap.
References
- TC AIM AIR 1.5.1
- TC AIM AIR 1.5.2