The pitot-static system supplies three instruments — airspeed indicator (ASI), altimeter, vertical speed indicator (VSI) — with pressure inputs.
Components
| Component | Measures | Location | Function |
|---|---|---|---|
| Pitot tube | Total (ram + static) pressure | Wing leading edge or nose | Provides dynamic pressure for ASI |
| Static port(s) | Ambient static pressure | Both sides of fuselage (slip compensation) | Provides static pressure for ASI, altimeter, VSI |
| Pitot heat | — | Electric heater in the pitot tube | Prevents pitot icing |
| Alternate static source | Backup static pressure | Cockpit valve | Used when main static ports are blocked |
Pitot heat pre-flight check
In pre-flight, briefly energise pitot heat and (carefully) check for warmth. Extended ground operation can overheat the tube — follow AFM.
Alternate static source — effect
In an unpressurised cockpit, internal pressure is typically slightly lower than ambient (Bernoulli effect of external flow). Switching to alternate static causes briefly:
- Altimeter: reads high (positive offset)
- ASI: reads high (higher differential)
- VSI: shows brief climb (apparent pressure rise)
Calibrate readings against known reference points after switching.
Pre-flight visual
- Pitot cover removed and visible as guard
- Pitot tube: clear, no insect, no obstruction
- Static ports: not taped, clean
- Drainage: drain low point if fitted