perf

[ccc111]

took the perf exam on 1st dec.
the question of why is the step climb used. same question came up in nov with only adhere to ATC being correct , but in dec same answer came up but this time increase range was one of the answers. any one know.

[figair]

hi ccc111
not that i'm an expert but to my knowledge a cruise climb would definetely increase range, however because it would be almost impossible to have every a/c on a cruise climb in our busy airspaces a Step Climb has been introduced. I therefore reckon that ATC compliance is the most correct answer for both questions.
Hope this helps you to relax while waiting for your result.

[Send Clowns]

I think you'll find it tough to get permission even for a step climb in busy airspace.

Looking at it in the way figair puts it then it depends with what you are comparing the step climb. If you are comparing it with trucking along level for the trip, then the purpose is to reduce fuel consumption (which does increase range as a side issue. Don't you hate JAA?). If comparing with a cruise climb then it assists ATC, and may aid adherence to ATC procedures. Then again in reality ATC may tell you to descend for traffic flow, so the answer is inelegant.

The point is the best answer I can see at the moment (note I have only taught P of F, not performance) is to increase range. Depending on how the question is worded, ATC compliance is a possibility, but I would have to see more precise feedback.

[pugzi]

I confir wholely with Sent Clowns.
I thought the answer for a longtime was to comply with ATC because I assumed the step climb was being compared to the cruise climb which is to always stay with the optimum altitude (Maximum specific range) which increases with a decrease in weight.
The thought of every one climbing ever so slowly throughout the flight and never staying level would probably push the Air Traffic controller over the edge. Thus you see the answer I thought of being to comply with ATC.
It is interesting to note, that this is how aircraft should operate, steadily climbing in the cruise to keep with optimum altitude. But alas, it is now not feasable with the current and future air traffic volumes. We should never have started this flying straight and level in the cruise business in the beginning of avation. If anyone can tell me why, I'd love to know. Perhaps it's a throw back from the military.
Anyway, sorry for the sidetrack. From various means I know the answer to be "increased range". Like Sent Clowns suggested, this answer arises if the step climb is being compared to the straight and level cruise. If you fly straight and level the optimum altitude will climb further and further away from you and reduce you maximum potential specific range. So, by step climbing, we would stay within 2000ft of the optimum altitude and increase our maximum potential specific range.
My "various" means of knowing this includes a performance result of 100% froma student who selected the answer as "increased range".
I'll leave you with a little problem.
What happens to specific range over time when flying at the optimum altitude?

Take care
Merry Christmas

[ccc111]

cheers for all your help . I also went for increased range.
the answer to your question would be for specific range to increase. have a good christmas.

[Alex Whittingham]

We've appealed this question several times. We thought the wording was this:

Q. Why are 'step climbs' used on long distance flights ?

(A) Step climbs do not have any special purpose for jet aeroplanes; they are used for piston engine aeroplanes only.
(B) To respect ATC flight level constraints.
(C) To fly as close as possible to the optimum altitude as aeroplane mass reduces.
(D) Step climbs are only justified if at the higher altitude less headwind or more tailwind can be expected.

Which arguably produces two possible answers. It could be (B) if the question means 'Why are 'step climbs' rather than cruise climbs used on long distance flights' and it could be (C) if they mean 'Why are 'step climbs' used on long distance flights rather than just maintaining one flight level throughout'

On balance I would have gone for (C) but there's no 'range' option in our version. Have you got a newer version of the question, Pugzi?