De Rated TO and Climbs

[Guest nigvilla]

I have started to experiment with different thrust settings via the FMC and 3rd party performance/calculation tool.No problems really but I wondered if the FMC thrust logic is working ok because at some point in the climb the EICAS readout changes from , say, CLB 2 to CLB and this is without any pilot intervention.Presumably the reduced climb operates up to some pre determined altitude or to a point just prior to Cruise mode?Nigel Thomas

[onurksn 1]

Hello Nigel,In the 737 reduced climb operates up to 15000 feet, above that it's normal CLB thrust.EDIT: I just found this in the manual, Chapter 8, page 38:CLB-1 reduces N1 by approximately 3% while the aircraft is below 10,000 feet and then gradually adjusted thrust upward so that both engines are operating at full thrust by the time the aircraft reaches 15,000 feet.CLB-2 reduces N1 by approximately 6% while the aircraft is below 5,000 feet and then gradually adjusts thrust upward so that both engines are operating at full thrust by the time the aircraft reaches 15000 feet.Hope this helps

[Guest nigvilla]

Thanks for that. That would seem to be the case, 15K feet was around where I noticed it.I may have missed that in the 747 manual- still reading it when the family allow!!!Nigel ThomasUK

[cavaricooper 2,614]

At 15000 the FMC commands CLB thrust- it is necessary to re-select if a derate is still required. Keep in mind the FMC selects CRZ at your VNAV cruise level- so should you want to remain in CLB you will have to manually re-select that as well.Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png| XP Pro SP3 - FSGS System Unification | 2 x APC UPS | Coolermaster Stacker 830 SE | Gigabyte P35 DS3R | e8500 @ 4gHz | Tuniq Tower 120 | EVGA 8800GT 512MB | Sony 40" Bravia XBR | Creative X-Fi Fatal1ty | Bose Companion 5 | 2 x 1 GB Corsair XMS2 | 2 x 320GB WD Caviar RAID 0 | Corsair HX620W PS | CH Products Yoke-Pedals-Throttle Quadrant | Aerosoft 747MCP-EFIS-EICAS |