Extra margins with assume thrust

[Gysbreght]

I've no reason to doubt the authenticity of the gradient information provided by FE Hoppy. We differ in the explanation for the decrease with temperature.


Many aircraft exhibit this, perhaps not always as pronounced as the E190. As explained by Keith Williams, elementary flight mechanics indicate that it is not caused by the increasing TAS, so it must be caused by decreasing thrust. A possible explanation is that the thrust of the uninstalled engine is flat-rated but installation effects, such as bleeds and the power absorbed by the accessory gearbox, increase with increasing ambient temperature, so that the installed thrust decreases.