CLB on EICAS as opposed to CRZ for 747-400

[TomCYYZ 215]

I am showing FMC ECON SPD .835 and I assume I am in CRZ mode or at least I think I am. But the EICAS reads (shows) CLB Mode. Should the Eicas be showing CRZ or am i missing something? My FL was 350 but OPT FL351 was showing in FMC. I went up to FL351 thinking maybe that was why the EICAS says CLB. But that didn't work. Is the thrust mode determined by the system or can it be overridden by myself? Regards,Tom

[lostmoon 0]

tom, you took the question right out of my brain. i was also curious about this because i experienced it on one ocassion. i didn't know what caused it, but i manually set the thrust mode via FMC. from FMC. -INDEX, then Thrust setting (or something like that, dealing w/thrust) then just hit the appropriate LSK that indicates "CRZ". this should change it.just a note: in the VIR19 744 video, PF was going through some of the indications on the upper eicas, and there, during cruise flight, the upper eicas was indicating "CLB". maxim(us)

[Mats_J 2]

Tom,It is usually determined by the FMC but you can override the thrust limit mode by pressing INDEX and THR LIM on the CDU and SELecting any mode you'd like once airborne.Hope it helps,

[markadeane 272]

I might be on the wrong track here, but what cruise altitude did you enter into the FMC prior to takeoff? If you entered - say - FL370 but levelled off at FL350, then the FMC might still assume you are in the Climb portion of your flight, so won't change the mode.This is just an educated guess as I don't have the manual handy and I'm at work. Anyone else feel free to step in and correct this.

[TomCYYZ 215]

Thanks Maxim, Mats, Mark. The information was exactly what I needed. Everything is working fine now. BTW Mark, FYI I did enter FL350 into the Fmc prior to T/Off.Best Regards,Tom

[Guest D17S]

And of course you know that the EICAS CLB/CRZ/OTHERS annunciation is just the current thrust limit. To see what Vnav mode you are in, press VNAV on the FMC. Often, crews will select a "CLB" thrust limit even though they are in Vnav's cruise mode. This is just to give thrust a little more "head room" if it needs it. In this case, you will have "CLB" annunciated on the EICAS screen and be in Vnav's "CRZ" mode ( . . . like they said).

[Qavion 19]

"Often, crews will select a "CLB" thrust limit even though they are in Vnav's cruise mode."This may be true (don't know), but it seems rather odd. The default thrust limit which appears in cruise is set according to company policy by maintenance engineers on the 744 FMC "PERF FACTORS" page (not shown in the sim, but it is one of the MAINT pages). I check and sometimes modify the values on this page after every Nav Database update.If the pilots think that a CLB thrust limit is safer in cruise, they should talk to their engineers about this, to have the limit remain in CLB (in cruise) automatically.Cheers.Q>

[Guest D17S]

One of our fellow simmers had a question about one of those 'over the shoulder' videos that showed a 744 in cruise with CLB set as thrust limit. I though "hummm?" too. So it was time for a test flight. Here's what I found. I found that in that at a cruise altitude when it came time to climb, VNAV SPD or FLCH SPD just didn't get much ROC. Of course VNAV SPD uses THR REF (to the CRZ thrust limit), but even that only got an anemic ROC. For a FLCH SPD climb, its "teammate" thrust mode, THR, went right to the limit too . . . even to get just its minimum 1200 fpm ROC. For a V/S climb . . . ahhh, don