performance question

[gphillips134]

performance question, can nobody answer this?

an aircraft is scheduled for take off, and requires 800m (TODR) under normal conditions at sea level. The following airfield characteristics need to be taken into account:Pressure altitude 2000ft QNH 1013 HPa Temp +21C, 5kt tailwind, 2% upslope, adjust the TODR accordingly using the following factors:

pressure alt +/- 20m / 1000ft
Runway slope +/- 15m/ 1% slope
Headwind -5m / 1kt
Tailwind + 10m / 1kt
temp +/- 5m / 1 degree ISA deviation


explaination would be helpful, cheers

[Lewy Boy]

All you do is add on the effect of each condition i.e

TODR=800m
PA=+40m (20m/1000ft and high elevation increases TO run)
Slope=+30m(15m/1% and upslope will increase distance)
Wind=+50m(10m/1kt and tailwind increases TO run)
Temp=+50m(ISA at 2000ft is 11.04c example is 21c so ISA+10.Warmer air increases distance again)

Hopefully the answer is around 970m. I had a few of these in my performance exam and passed it so hopefully this is the correct method.

Good luck

[FlyingForFun]

I believe you are actually supposed to multiply the effects, not add them......? They are "normally" expressed in terms of a %age addition to the distances required, though, not an absolute value, so not sure how you'd do that in this case. Possibly convert each individual value to a %age, then multiply the %ages together???

FFF
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[peb]

Im agree with you, I think that is the right answer. 970 meters

[gphillips134]

well done to the first respone

well done to the first responce the answer was indeed correct not to difficult once someone has taken five minutes to show you how its done

thanks again