Polar Diagram - how is it calculated?

[Runway 31]

John,

I am going to hazard a guess and suggest that in colder weather the aircraft climb performance is better and the contents of http://www.skybrary.aero/index.php/AP4ATCO_-_Factors_Affecting_Aircraft_Performance_During_Takeoff_and_Climb  may offer an explanation which I hope may be relevant to your question.

Alan

[neroon79]

Your are right Alan,

Cold air has a higher density than warm air, that's by the way the reason why Emirates boss is complaining about the performance of the bigger dreamliner versions. In hot desert air the density and therefore the "air lift" and engines thrust performance is that low, that the dreamliner won't take off if full cargo is loaded in the airframe.

Ingo

[FACTflights]

Alan,

Very interesting indeed, so my assumption was correct.

We have mountains all around us except to the South.  Table Mountain is about 5 kM to the West and the other mountains start at about 80kM to the east.  To the North we have a small gap through which we see the BA flights to EGLL.

The aircraft have to gain altitude pretty quick to clear the high points.

To the South we see the flights to Anarctica.

[FACTflights]

Screen shot

[Runway 31]

Yes the surrounding terrain will impact on what you see as well.

Alan