What FLEX temperature means on the A320neo

FLEX temperature is an assumed temperature entered for a reduced-thrust takeoff. It is not the measured outside air temperature. A higher acceptable FLEX value generally represents a larger simulated thrust reduction, while TOGA requests full rated takeoff thrust.

The correct value depends on aircraft weight, runway and atmospheric conditions. It cannot be selected safely from weight alone, and a value from a previous flight should never be reused without recalculation.

Inputs required for a useful estimate

Select the A320-251N profile and enter gross weight, CG, flap setting, packs and anti-ice configuration. Add runway length, takeoff shift, elevation and slope, followed by temperature, QNH and wind.

Takeoff shift is especially important for an intersection departure because it reduces effective runway length. Tailwind, high temperature, high pressure altitude, wet or contaminated surfaces and uphill slope all consume modelled margin.

  • A320-251N takeoff weight
  • Actual departure runway and takeoff shift
  • Runway surface and slope
  • OAT, QNH and wind
  • Packs and anti-ice configuration

Why the calculator may show TOGA

The tool displays TOGA when its calculated FLEX temperature falls below the usable threshold or is incompatible with the entered outside air temperature. This commonly occurs with a short runway, high weight, tailwind, contamination or a combination of smaller penalties.

TOGA is a thrust-mode result, not a runway-performance certification. If warnings remain, change the runway or configuration and check the aircraft add-on documentation.

A320neo workflow in MSFS and X-Plane

After calculation, compare V1, VR and V2 with the values expected by the specific A320neo add-on. Enter the FLEX temperature only in a simulator aircraft that supports the Airbus FLEX workflow. Recalculate after any change to weight, runway, weather or takeoff configuration.

The model is designed for flight simulation and education. It does not contain official Airbus FCOM tables or certified operator data.