Hi, I have a question about the Top of Climb and using a derated climb power, how can I make the FMC calculate the TOC using either Climb 1 or Climb 2 thrust modes?, because the TOC is always calculated using the normal CLB mode.I will appreciate any answer. MXA320.

What is a normal climb profile? The top of climb is calculated by your set crz altitude. Even if you choose to use a reduced climb thrust, how does that change your selected speed? Also, with step climbs, manual ECON climb speed changes, speed restrictons, ATC issed altitude holds, direct climbs {restrictions removed during climb} and the option of using our optimum crz altitude thrown in the mix, I hope I would not have to calculate the FMC predicted items.Best Wishes, Randy J. Smith [h3]" A little learning is a dangerous thing"[/h3]AMD XP 2100 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF3 64 MEG |WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"

Hi Randy"Even if you choose to use a reduced climb thrust, how does that change your selected speed?"It doesn't, only your climb rate will be lower and thus you'll need a longer time to reach the CRZ level, thus the distance to the TOC will be higher than with max CLB pwr.To come back to the original question, I don't really know! I must say it is a good one and I want to find the answer to it aswell.RegardsMark

That's what I was trying to show him by asking the question. If you have chosen a crz flt lvl @ 290' but decide to go for the FMC calculated optimum @ say 310', the FMC will re-calculate this for us without us "needing" to do anything to the FMC. Plus, where is it taught that the T/C is calculated using the "normal climb thrust"? If one comes to a conclusion based on a mistaken assumption, then the rest of assumption must also be wrong.Best Wishes, Randy J. Smith [h3]" A little learning is a dangerous thing"[/h3]AMD XP 2100 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF3 64 MEG |WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"

Randy,Probably you didn't understand my question, my question is exactly what Mark said. I'm not saying that in the manual is said the TOC is calculated using the normal Climb Power, however, the next time you use the PIC, derate the Climb Power, using either CLB1 or CLB2 and your VS will drop because the plane won't be able to keep the same nose angle since it will start to loose speed, and this will cause to level some miles after the expected TOC. (The CRZ power setting is not a factor here).Now, when you use the normal CLB power, the plane always levels at the TOC, it is always perfectly calculated by the FMC.My question was, How can you make the FMC calculate the TOC using a derated Climb Power, since your rate of climb will be lower than using the full climb power?...Thanks anyway, MXA320.

The short answer is you can't.I don't have my manual right now but CLB2 and CLB1 power washes out aroud 12,000 feet and you MUST switch to full power. As I'n sure you noticed, if you don't switch to full power the green arc and T/D indicator keeps recalculating and noving forward.

That was my assumption aswell. But maybe it's an option for some airlines that the FMC uses whatever mode is set on the TRP for TOC calculations (just a wild guess here). On the other hand, why bother? ;-)TOC is not really THAT important. A good ball park figure will usually be enough.Anyhow, the time when you set CLB1 (from CLB2) and CLB (from CLB2) really depends on your weight, ISA deviation etc. On light aircraft you can use CLB2 up to 20k feet zone. But your TOC calculation will be off!Also, what I saw, is that after a while the TOC is being pushed ahead if you haven't reached it within the first prediction. Maybe it does somehow use average or current V/S to calculate TOC. Again, maybe I'm wrong. But the question is really good ;-)RegardsMark

>On light aircraft you can use CLB2 up to 20k feet zone.Climb derate (CLB1 or CLB2) on the B767 'washes-out' and changes to full climb thrust at 11000-13000ft.Regards

>Climb derate (CLB1 or CLB2) on the B767 'washes-out' and >changes to full climb thrust at 11000-13000ft.This is actually a company/software/something option, and some aircraft behave just like PIC: the derated climbs don't "wash out" into full climb thrust.Martin767 fetishistIt's a lot like life and that's what's appealing

But it should be noted that on those aircraft procedure is to switch to full climb power at some point in the low teens. Reduced thrust is never used all the way up.But to answer the original question more precisely, PIC does not take into account reduced thrust in its predictions.Wade

Martin: Maybe you are referring you the B757 where the derate doesn't wash-out?Because I know for sure that for the B767, (real-life at least, not sure about PIC?) CLB1 or CLB2 changes to full CLB thrust automatically at about 12,500ft. I do not know the reason, but I suspect it's because the B767 does not climb so well at the higher altitudes. Yes Wade is right, usually you don't keep the derated thrust all the way throughout the climb in those aircraft which derates don't 'wash-out'(eg.757). When the rate of climb gets to less than 1000fpm, a higher climb setting would be set by the pilot (CLB1 over CLB2 or CLB over CLB1)Regards

GE,That feature could very well be a company option.Anyway, when I said CLB1 could be used to the 20k feet zone, I was referring to LIGHT aircraft. Not a 767 loaded to the MTOW...RegardsMark

Yes Wade is right, usually you don't keep the derated thrust all the way throughout the climb in those aircraft which derates don't 'wash-out'(eg.757). When the rate of climb gets to less than 1000fpm, a higher climb setting would be set by the pilot (CLB1 over CLB2 or CLB over CLB1) Here's what a 757 pilot friend has told me a while back."We derate most of our take offs using an assumed take off mass and also preselect climb pwr 2 until the rate of climb at econ climb speed reduces to less than 1500 fpm then select climb 1 and so on.Best Wishes, Randy J. Smith [h3]" A little learning is a dangerous thing"[/h3]AMD XP 2100 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF3 64 MEG |WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"

I don't think it's a company option, it is probably already programmed into the TMC by Boeing. And it does not matter whether you are light or at MTOW. Either way, the derate 'washes-out' at 12,500ft for the B767, giving full climb thrust all the way until cruising altitude. May I know where you got this info about you being able to use CLB2 derate all the way until 20k feet?Thanks.Yeah I agree with Randy, most 757 operators use CLB2 derate as standard procedure, only removing the derate when rate of climb drops below 1000fpm. After all, the 757 is a really powerful plane. :)Regards

It's correct for the 767 that as the aircraft passes through 12'500, a selected reduced climb thrust automatically changes to maximum climb thrust. Best Wishes, Randy J. Smith [h3]" A little learning is a dangerous thing"[/h3]AMD XP 2100 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF3 64 MEG |WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"