POST/api/v1/e6b/true-airspeed/calculateCommercial Pilot

Calculate True Airspeed

Calculates true airspeed (TAS) from calibrated airspeed, pressure altitude, and outside air temperature.

Code Examples

curl \
  -X POST \
  -H "Ocp-Apim-Subscription-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "calibratedAirspeedKt": 0,
  "pressureAltitudeFt": 0,
  "outsideAirTemperatureCelsius": 0
}' \
  "https://api.preflightapi.io/api/v1/e6b/true-airspeed/calculate"

curl \
  -X POST \
  -H "Ocp-Apim-Subscription-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "calibratedAirspeedKt": 0,
  "pressureAltitudeFt": 0,
  "outsideAirTemperatureCelsius": 0
}' \
  "https://api.preflightapi.io/api/v1/e6b/true-airspeed/calculate"

Description

Uses the full compressible isentropic flow conversion (CAS to impact pressure to Mach to TAS), accurate from sea level through FL410+ including above the ISA tropopause at 36,089 ft. This is more accurate than the simplified CAS / sqrt(sigma) formula, which diverges significantly at higher altitudes.

Response Fields

TrueAirspeedKt — the aircraft's actual speed through the air mass (knots)

DensityAltitudeFt — density altitude at the given conditions (feet)

MachNumber — the aircraft's speed as a fraction of the local speed of sound

*Note:* The ISA tropopause is modeled at 36,089 ft. The real tropopause varies from ~26,000 ft near the poles to ~55,000 ft near the equator, which affects accuracy at high altitudes in non-mid-latitude regions.

Request BodyTrueAirspeedRequestDto

calibratedAirspeedKtnumber

Calibrated (indicated) airspeed in knots (must be greater than 0)

pressureAltitudeFtnumber

Pressure altitude in feet (can be negative, e.g. Death Valley)

outsideAirTemperatureCelsiusnumber

Outside air temperature in degrees Celsius

Response Schema

200Returns the TAS calculationTrueAirspeedResponseDto

trueAirspeedKtnumber

Calculated true airspeed in knots

densityAltitudeFtnumber

Density altitude in feet at the given conditions

machNumbernumber

Mach number at the given conditions

calibratedAirspeedKtnumber

Calibrated airspeed used in calculation (knots)

pressureAltitudeFtnumber

Pressure altitude used in calculation (feet)

outsideAirTemperatureCelsiusnumber

Outside air temperature used in calculation (°C)

400The request parameters are invalid (e.g., CAS is zero or negative)ApiErrorResponse

codestring

Machine-readable error code (e.g., "AIRCRAFT_NOT_FOUND").

messagestring

Human-readable error message suitable for display.

detailsstringnullable

Additional error details (only included in development environment).

servicestringnullable

Name of the external service that failed (only included for 503 errors).

validationErrorsRecord<string, string[]>nullable

Field-level validation errors (only for validation failures).

timestampstring

UTC timestamp when the error occurred.

traceIdstringnullable

Correlation ID for tracing the request.

pathstringnullable

Request path that generated the error.