What are the key factors in climb rate?

Sorry, that sounds a bit geeky!

Was sat in garden yesterday, nice glass of red in hand, enjoying the cooler temperatures though still very warm in South London.

With the wind from the East I get a good view of planes heading to Europe or beyond on such evenings and a couple of Virgin 346s were among them - I did notice that one in particular, was very low in the sky compared to other planes and wonder what factors are key in determining climb rate? I hear that temperature, elevation, weight of course and others are involved, keen to know more ...

[preiffer]

The other HUGE factor is their clearance from ATC after takeoff...

A340s do tend to have a slower rate of climb than other aircraft, don't they?[:?]

VS045

[preiffer]

Well, I think slinky's query was more around why some (of the same type) planes are slower climbing than others, and yes - that comes down to operating specifics and ATC.

NOT wanting to open up the whole 777v340 debate (PLEASE keep that in the new aircraft thread), I did just randomly run across this site which offers a pretty decent perspective on the issue.

Basically, VS045, the 343 had a lot less power than the 346 - which may explain that general observation.

Wasn't trying to start an A vs. B debate - actually I prefer a slower rate of climb;)

VS.

Certainly wasn't trying to start a debate about the 340 ... rather things like is the rate of climb less in hot weather, and why?

The ask a captain site is pretty cool - I know more about ETOPS now so will stop going 'doh' when all you very intelligent dudes go on about it!

Noise regulations would also affect climb rate as well wouldn't they? Maybe not for the initial climb, which will be done at pretty much full power, but shortly after take off, power is always reduced for noise abatement. This varies from airport to airport (but should be consistent if you are comparing aircraft at the same airport).

Originally posted by slinky09
Certainly wasn't trying to start a debate about the 340 ... rather things like is the rate of climb less in hot weather, and why?

Good question, just had a chat with my old freind wikipedia, and it appears that "The air temperature affects the efficiency/fuel consumption of aircraft engines."

So the hotter the temperature, the less efficient the engines, meaning a longer take off run, and slower rate of climb.

Hope this helps!

Yes, hot (and high) does mean a longer take-off run - look at Jo'burg;)

VS.

Apart from the usual variations in weight of the aircrfat, longer flight = morefuel etc, cargo weight varies as well. The other factor is that at certain weights and weather/temperature conditions, the aircraft may not need to use full power for the take off, but a slightly reduced pwer level. This may give a slightly longer take off run and slower climb (initialy). The use of a lower than full power setting is very common and is to reduce the wear on the engine (also fuel saving, but mainly to extend the life of the engine). All these take off's are automatically monitored so the airines can base the overhaul of the engines on the actual use they have had.