Good morning,
@Denti: thanks for correcting my assumptions. I think that almost completes the (abridged) picture for Boeing derated TO procedures and that's what I needed. I just have one more question about that washout bit: if you use CLB and not CLB-1 or -2, then there is there any washout at all as you climb? I'm thinking there shouldn't be, just want to make sure.
@RunSick:
Thrust must not be reduced by more than 25% of the full derated takeoff thrust.
The flexible takeoff thrust cannot be lower than the Max Continuous thrust used for the final takeoff flight path computation (at ISA +40)
Let's rephrase this: FLEX thrust can be as low as 75% of full thrust, yet it is always more than or equal to Max Cont Thrust at ISA +40? So this MCT at ISA +40 is some sort of lower limit?
@barit1: indeed it sounds counterintuitive, and also to me as an ATC.
Based on all contributions so far, here is how I intend to describe a simplified behaviour for our Tower simulator:
- TO thrust is reduced, with a minimum value defined per aircraft type (we cannot used operator-based values here, but aircraft-based should be good enough). The method used will be assumed temp/FLEX, as I don't think we can incorporate Boeing's Derate + Assumed temp easily in this context.
- Climb thrust should never exceed 95% (to be adjusted) of maximum TO power. This should simulate some form of Max Cont Thrust.
- Whether the aircraft should be allowed to *increase* thrust at thrust "reduction" altitude should be a toggle switch, per-aircraft if possible, globally otherwise.
I'll also try to get in touch with a couple of carriers operating from LFPG and see whether they use increased CLB thrust to save fuel, even though there are usually steps at FLs 100-120 when there is downwind traffic across your path.
One last item I would like your input on is the difference in ROC between an unrestricted climb and a derated one. I guess that if the savings are minute (about 100kg?), the ROC can't be too different, maybe 500fpm max? Any figures to confirm or infirm that reasoning?
Thanks a bunch!
--
Romain