because all your doing is reducing the performance limited TOW, but not below the structural limited MTOW.
Airbus software has an option where it wont show specific runway takeoff weights above structural TOW. This appears to have caused some confusion as some seem to believe that this is the highest weight that you can achieve. If you look at a Boeing chart for say a B772, it has a Structural TOW of 286.8 kgs, but the chart shows weights up to 315.0 kgs. If you plot these weights you can easily see the difference between the takeoff weight achievable with Full Thrust and Derated Thrust, on a specific day/runway, you may achieve structural takeoff weight with both thrust ratings, but there will be a difference between them. (Not including other limits such as tire).
We used to increase taxi fuel, at captains request, sometimes to 1000kgs, to not exceed MTOW on loadsheet. I used to watch take-off rolls from office holding my breath
I'm assuming that you do know the difference between Maximum Structural Takeoff Weight and Maximum Ramp Weight?
I enjoy trying to increase my knowledge and understanding, as fATPL theory only skimmed the perimeter.
OK, then answer this, why does Boeing publish takeoff weights above Maximum Structural?
Mutt