Jump to content
Sign in to follow this  
Robinnn

Recommended flightlevel much lower then optimal flightlevel

Recommended Posts

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

Share this post


Link to post
Share on other sites

Hello,

 

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

Opt, max and recmd altitudes are explained there.


Romain Roux

204800.pngACH1179.jpg

 

Avec l'avion, nous avons inventé la ligne droite.

St Exupéry, Terre des hommes.

Share this post


Link to post
Share on other sites

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:


Bill

UK LAPL-A

Currently flying:- (GA): COWS DA-42, A2A Comanche, FSW C414, WT SR22T, FSS P2006, BlSq TBM850, FSR M500, Flyboy Rans S6S, SWS Zenith 701,C172 JT-A mod (Airliners): Fenix A320, Ini A300-600, FBW A320 NEO and PMDG737.

Share this post


Link to post
Share on other sites

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.


Romain Roux

204800.pngACH1179.jpg

 

Avec l'avion, nous avons inventé la ligne droite.

St Exupéry, Terre des hommes.

Share this post


Link to post
Share on other sites

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?

Share this post


Link to post
Share on other sites

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.


Romain Roux

204800.pngACH1179.jpg

 

Avec l'avion, nous avons inventé la ligne droite.

St Exupéry, Terre des hommes.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
×
×
  • Create New...