FMC Cruise altitude question

[vegasjon 39]

Hello!

 

This is about my 10th flight with the 747 and no problems yet. However, this question is the first thing that has come up. All my previous flights followed the FMC programming correctly. Today, I planned a flight with PFPX, set a cruise Alt for 360 in the FMC as well as on the console, no problem. However, the FMC is calculating in  the LEGS section a FL of 430...I went into the VNAV setup and changed the Cruise alt back to 360, and the first 3 waypoints went to 360 but afterwards a step climb back up to 430,,. 

 

Any thoughts as to why this happens? Maybe turn off auto calculate step climbs?

[skelsey 765]

Hi Joe,

 

First off -- check that your weights are correct. The FMC will always calculate step climbs and optimum altitudes for you and propagate these along the route in order to provide a sensible fuel prediction (but it will not override what you put in the cruise FL).

 

If you do not want the FMC to calculate step climbs, simply set the STEP SIZE to 0.

[vegasjon 39]

Ok...Thanks for the information!