13.8 Instruments (ATA 31) — air data, gyros, compasses, GPWS, FDR, EFIS and warnings
1,286 words · checked 2026-10-03 · Pro
Scope
Level 3 for B2 and the whole exam for the B2L Instruments rating. The AMC list is long: classification, atmosphere, terminology, pressure-measuring devices, pitot-static, altimeters, VSI, ASI, Machmeters, altitude reporting/alerting, ADC, instrument pneumatics, pressure and temperature gauges, temperature indicating, gyroscopic principles, artificial horizons, slip indicators, DGs, GPWS, compass systems, FDR, EFIS, warning systems, stall warning and AoA, vibration measurement, glass cockpit, test equipment.
Classification
Flight instruments (attitude, airspeed, altitude, heading, vertical speed, turn), navigation instruments, engine instruments, and system instruments (hydraulic, fuel, electrical...). Also by principle: pressure, temperature, gyroscopic, magnetic, electronic.
The ISA atmosphere
| Parameter | Sea-level value |
|---|---|
| Pressure | 1013.25 hPa (29.92 inHg) |
| Temperature | +15 °C |
| Density | 1.225 kg/m³ |
| Lapse rate | About 2 °C (1.98 °C) per 1,000 ft up to the tropopause at 36,089 ft, where temperature is −56.5 °C and then constant |
Pressure falls about 1 hPa per 27–30 ft near sea level.
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