If you were at max altitude and the selected speed was below the upper amber band, how would you know which of the three thrust based limitations were ' active' so to speak?
I skipped over the limits you posted in your last post, because they didn't make sense to me. I thought we agreed long ago, that we are e.g. not service ceiling limited at FMC max altitude. I know of only 2 limit: 100fpm at LRC speed and 300 fpm during climb.
can you provide a reference for that because the JTPM written by Boeing has lead me to believe that BEST SPEED is nothing more than the speed at which the engines would have the minimum rate of fuel flow and can be a speed well below min drag.
Only from the FMC User Guide. I downloaded the JTPM, and it is a lot of general observations and theory. I would be careful to apply that as a manual for a specific aircraft model. The FMC User Guide, although being unofficial, deals specifically with 737. Further more, there are no warnings in any of the official documents, that the FMC suggested holding speed may be below thrust limit to actually do a hold. 1) Would it make sense to let the FMC suggest such speed? 2) Wouldn't Boeing warn about it if it did?
Seeing as Max alt is sometimes limited by the ability of the engines to power you through a 15 degree banked turn I can't see how that speed would allow 15 degrees with the extra drag of being below min drag.
I
assume that the suggested holding speed would increase to Vmd if that was the case. I will play with the gross weight on the perf init page on the next flight to have a look, but don't know if this speed is entry or sensor based. As I said some posts back, this speed never interested me, as I never hold at high altitude (European ATC apparently better than Australian
).
I have no argument with this practice but can see why pilots coming off other Boeings might, in some Max Con is only to be used in emergencies. If the Climb N1 and the Max Con N1 are the same there is no restriction and that applies to the NG.
In Boeing CON and CLB are not the same at low altitude. Say at FL200 you may have 95% CLB and 100% CON. I use CON too, if asked if I can make an altitude restriction. Why should MCT be limited to emergencies, for ANY aircraft?
MCT = Max
Continuous Thrust. You can fly
continuously all day with that setting if you like. Max takeoff thrust is more of an "emergency" thrust setting, as you are limited to 5 or 10 mins.