Performance increase from FLEX to TOGA Takeoff in an Airbus

[Goldenrivett]

Hi CokeZero,
If TOGA thrust is flat rated to +28 degs C (301 degs Kelvin), then FLEX probably reduces the engine thrust by approximately 10% for every 30 degs C above 28 degs C.

So if you planned to set flex to 40 (12 above + 28) but then set TOGA, then you should get an extra 12/301% thrust (i.e. about 4%).

If you needed say 80% thrust Single Engine just to fly level without accelerating, then every 1% increase in thrust (above 80%) increases your performance by approximately 5%.