747 no descend at T/D

[Guest GrandSurf]

I learn to flight on the 747 with the german Tutorial of J.A.Schenk. Actually everything goes without errors but on the T/D Point the 747 does not begin to sink. 3000ft are adjusted to the MCP and the FMC is correctly programmed (look Pictures down). The heights are not taken over from the FMC as in the Tutorial described. Why not? I am surely no error to have made... thanks for tipps...greets Steffen http://www.smay-racing.com/images/sonstiges/747_10.jpghttp://www.smay-racing.com/images/sonstiges/747_11.jpg

[engwerda 0]

Steffen,Did you break the flight at any stage and save it? I resumed a saved flight recently and had the same problem - it would not begin a descent when it reached the T/D point.Gerry

[Guest GrandSurf]

Yes, i have save in flight. I should not do that?Steffen

[engwerda 0]

Steffen,By all means save the flight but it does not seem to save everything. Check your light switch positions when you resume a flight as a case in point. Often after saving a flight I let the AP fly it to the T/D point and then I set a new altitude in the MCP and use Fltch (Flight Change button on the MCP) to take me down. From there on it is a matter of checking the green arc occasionally.I seem to recall a discussion on this before and there was some talk of a two stage process for saving flights but I cannot remember what that was.Gerry

[Guest GrandSurf]

Ok, thx - i wants to repeat the flight today without a resume. Pause "P" the sim in the flight is no problem,or?Steffen

[engwerda 0]

No pressing P for Pause is not going to be a problem.All the bestGerry

[Tabs 2,790]

Steffan,Why are you in VNAV ALT mode there? It should be in VNAV PTH. VNAV ALT indicates that the FMC commanded action has been stopped by the MCP ALT knob - try pressing the ALT knob and see if it goes into PTH mode. Was it in PTH mode prior to T/D? It should be - if you're seeing VNAV ALT happen at cruise, something is wrong with the way you set up the FMC.

[craig_read 43]

Yeah.. as above .. VNAV ALT means the autopilot pitch control is set to hold a specific altitude while in a managed VNAV mode.... When exactly did you change the altitude bug from 39,000feet to 3,000 feet? Was that after you passed the T/D point or quite a way before? Correct me if I'm wrong everyone.. but I believe.. that if you let the aircraft go over the T/D point without changing the bug giving VNAV the freedom to begin the descent, it will automatically change to VNAV ALT.. holding the current altitude until you instruct it to descend with a knob push.... simply changing the altitude bug will not change the altitude in VNAV ALT.. you need to tell it to do so.. buy pressing the bug.. Again correct me if I am wrong.. but pressing the altitude knob ONCE.. will instruct the autopilot to ignore the current altitude restriction placed on it (39,000 feet FL390 here).. in it's descent, and should try to bring the aircraft onto the descent path.. Again correct me if I am wrong.. but since you are quite some way off the path.. VNAV PATH won't show right away.. only once you get close.. at this point in the descent.. I would use a Flight Level CHange (FLCH) to attempt to get control of the descent in a manual mode before giving control back to VNAV..CheersCraig

[Guest mcalpinep]

Hi Steffan,Craig is correct in his previous post, as a small addition your landing gear switch should be set to OFF (central position) and I think you might have overestimated your fuel requirement , having > 55 Tons on board at this point in the flight is a bit excessive. :) It took me a good while to accurately set fuel requirements, the PMDG manual on fuel planning is well worth a read.Enjoy,Phil McAlpine.