Airspeed Rechner — Formel
## Indicated vs True Airspeed
Indicated airspeed (IAS) is what the pitot-static system reads, calibrated for sea-level standard density. As altitude increases and air density decreases, the true airspeed (TAS) becomes higher than the indicated reading.
### Simplified Relationship
**TAS = IAS / sqrt(sigma)**
where sigma is the density ratio (local density divided by sea-level standard density). This approximation is valid for low subsonic speeds where compressibility effects are negligible.
Indicated airspeed (IAS) is what the pitot-static system reads, calibrated for sea-level standard density. As altitude increases and air density decreases, the true airspeed (TAS) becomes higher than the indicated reading.
### Simplified Relationship
**TAS = IAS / sqrt(sigma)**
where sigma is the density ratio (local density divided by sea-level standard density). This approximation is valid for low subsonic speeds where compressibility effects are negligible.
Lösungsbeispiel
An aircraft reads 250 KIAS at 10,000 ft pressure altitude with OAT of -5°C.
- ISA temperature at 10,000 ft = 15 - 1.981 × 10 = -4.81°C
- Temperature ratio component = 288.15 / 268.15 = 1.0746
- Pressure ratio component = (1 - 0.000006875 × 10000)^4.2561 = 0.6877
- Density ratio sigma = 1.0746 × 0.6877 = 0.7392
- TAS = 250 / sqrt(0.7392) = 250 / 0.8598 = 290.8 knots