I noticed something when flying my PIC/POSKY merged aircraft. When i reach my cruise altitude, for example FL310, my engine configuration does not change automatically from CLB to CRZ. In the PIC FMC manual they say it's supposed to change automatically, but it doesn't. What can be wrong?Cheers!

It changes automatically from CLB to CRZ for me.Lee Hetherington (KBED)

It's a known bug. It doesn't change to CRZ consistently. It seems to have something to do with whatever climb thrust mode you had set previously before capturing your cruise altitude. Sometimes it works, sometimes it don't ;-)Cheers,J

Well in my case it has never worked! :(

Just change it yourself, several airlines have their 763s programmed to stay in CLB during the cruise anyway I recall.Anyway it works for me but only when using no thrust derate both for takeoff and climb.

Are you using VNAV for the climb?

No, not using Vnav, I think Vnav is the only setting I don't use in my FMC config. Could it be it?And for the person who said some airlines set their engines to clb during cruise, doesn't it use more fuel?Cheers!

>And for the person who said some airlines set their engines to clb during cruise, doesn't it use more fuel?CLB and CRZ only represent a thrust limit, Gustavo. That is, the engines will only go to the limit if they are required to go to the limit (and they shouldn't be required go to that limit in cruise under normal circumstances).By the way, these modes can be changed by Maintenance (although it has been a while since I last had to change them... and can't remember what our airline has them set to. Our 747-400's have "CLB" as the cruise limit however).Cheers.Ian.

Yes, I can tell you that you will need to be in VNAV for this transition to CRZ mode to automatically take place. Don't be surprised if it doesn't do it consistently, however - especially if you manually change thrust modes during your climb (i.e. use a derate, and manually move from CLB2 to CLB1, etc...)J

Interesting, I almost always derate the takeoff and manually go from CLB2 to CLB1 to CLB, and I'm pretty sure I always end up in CRZ when VNAV levels off. Knock on wood.Lee Hetherington (KBED)

Good to know that, I thought that by increasing the engine workable limit it affected the fuel consumption.Btw, what airline you work for?

So do I...but I have occassionally seen this behavior (I'm not certain what the magic combination of events is) and I know Eric and Wade have mentioned it on this forum in the past.J

>Good to know that, I thought that by increasing the engine >workable limit it affected the fuel consumption.This is more complicated than I thought, Gustavo....Just found this in my manuals...On the Airline Policy page 1 of 2 of the Pegasus FMC (not shown in PIC), line 3R "THR/CRZ" defines "the default thrust rating to be used in all-engine cruise (and) defines the minumum rate of climb margin at cruise thrust and cruise speed for use in all engine maximum altitude computation. The default values are: CRZ/0"I'm currently wading through the Bulfer Big Boeing FMC User's Guide to see how this relates to Max Alt. and Optimum Cruise altitudes/speeds. I suppose with more thrust available, you can cruise at higher altitudes. Whether this increases/decreases fuel burn, I can't say. Throw Cost Index into the mix and you have one complicated issue. Sounds like a question for Bill Bulfer's Bluecoat forum, but I haven't been able to access it for at least a month. >Btw, what airline you work for? My company probably wouldn't approve of me divulging this, Gustavo, so I'll just say that I work for a major Australian international airline (Shouldn't be too hard to figure out now that Ansett has departed :-hah).Anyway, I'll let you know if I come up with an answer to the CRZ/CLB issue ;-)Cheers.Ian.

I use de-rated T/O and CLB all the way. I get CRZ when going from VNAV SPD to PTH (transition to cruise) everytime. Not a problem!