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Robinnn

Recommended flightlevel much lower then optimal flightlevel

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Enroute from KIX to AMS with a fully loaded B77W KLM.

I noticed during climb, my recommended flightlevel is much lower then my optimal flightlevel.

Why is that?

 

2015-12-26_10-38-33-5v8s5p.jpg

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Hello,

 

Have a look at the FCOM v2 page 11.42.26 (pdf p. 1030).

Opt, max and recmd altitudes are explained there.

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As far as I recall, "optimum FL" will take account of aircraft weight, INIT settings, etc, whereas "Recommended FL" will also take account of the length of the flight plan route.   So although the optimum (from an efficiency perdpective) may be higher, if the leg is quite short, the recomended may be lower.

EDIT:   I've just seen that this was a leg from Japan to Europe, so the above is unlikely to explain it in this case :nea:  :smile:

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As far as I recall, "optimum FL" will take account of aircraft weight, INIT settings, etc, whereas "Recommended FL" will also take account of the length of the flight plan route.   So although the optimum (from an efficiency perdpective) may be higher, if the leg is quite short, the recomended may be lower.

 

EDIT:   I've just seen that this was a leg from Japan to Europe, so the above is unlikely to explain it in this case :nea:  :smile:

 

Not exactly. Refer to FCOM page I pointed on my previous post.

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I still don't get it. Normally the recommended flightlevel is much closer to the optimal flightlevel. Sometimes even between recommended and max. flightlevel.

Why not in this case?

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I still don't get it. Normally the recommended flightlevel is much closer to the optimal flightlevel. Sometimes even between recommended and max. flightlevel.

Why not in this case?

 

Have you entered some winds in the rte data? If yes, it may be because the FMC computes that for the next 500nm it is much more economical to fly at fl260, considering the actual weight and the wind while for the whole trip considering the actual weight and the CI, FL297 is more economical.

If for the following next 500nm the winds went to be more favourable at a higher level, then the recmd FL would be higher.

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