747 VNAV mode

[DF9AA 0]

Hi, after 100+ flights with the 747 on FSX I had another first. . .initial alt selected before T/O was in both cases 6000ft - normal T/O LNAV/VNAV engagedAfter receiving clearance to FL180, tried to enter the alt in MCP ( as before 100 times . . .) the VNAV mode disengaged and V/S mode came up .A/T was still engaged but moving the hand throttle it changed the thrust.The speed indication on the PFD disappeared.Unable to reengage the VNAV mode.Any ideas or explanations ?Thanks

[engwerda 0]

Karl - HeinzTry double clicking on the VNAV button or if that does not work- set VS to +1000 or so and once the climb starts reengage VNAV.,Gerry

[downscc 1,327]

You must have changed focus at some point, by that I mean another window or dialog box gained the focus from FSX and on regaining the focus you will loose VNAV in spite of it indicating its presence. Simple double press of VNAV resets the logic and you are good to go.

[DF9AA 0]

Thanks Dan and Gerry,double-klick did not solve the problem . . .Just performed the same T/O ( same weight etc ) with the 744F - no problems at all - I fear the 744pax code is corrupt and I have to reinstall.Will do further tests

[DF9AA 0]

Hi ,another first :After two take-offs with the RR 747 ( others I cannot tell so far ) I had the followingNormal T/O preps - line up, thrust to T/O power and . . . klick on TOGA screw . . .TAKE-OFF SPEEDS DELETEDAny ideas ?p.s. I feel I have to reinstall . . . too many hick-ups!

[Guest ironhorsmn]

I haven't flown the FSX version, but I assume the proceedures are the same between both versions. I haven't seen anyone mention this, but every once in a while I forget to click on the altitude set know after resetting the altitude.Leave the VNAV button alone when resetting alltitude, unless it has become disconnected whereby it is still illuminated but not working.When ATC clears you for the next altitude target, reset the MCP altitude select, then click the button once. This sends the altitude setting to the flight control computer. If everything is set for the climb, the aircraft should after a brief wait for the engines to spool up, begin to climb. If it does not, then click the VNAV button even if it is illuminate. Remember that the VNAV button being illuminated only indicates that it is armed and not necessarily active.This proceedure is so basic, that I sometimes overlook it, and then when ATC starts yelling at me to expidite my climb I start clicking on everything trying to get the bird to climb. If this is the proceedure you have been following, then I am at a loss.John

[zachlog 18]

Hi ,another first :After two take-offs with the RR 747 ( others I cannot tell so far ) I had the followingNormal T/O preps - line up, thrust to T/O power and . . . klick on TOGA screw . . .TAKE-OFF SPEEDS DELETEDAny ideas ?p.s. I feel I have to reinstall . . . too many hick-ups!

Karl,The VNAV disengaging happens frequently with me when I load a flight after having saved it. When it disengages, the SPD indicator also disappears on the PFD. But in all cases, it re-engages after a couple of presses of VNAV (per Dan's note). You indicated that you're flying "RR 747"....did you by any chance change to an aircraft with different engine type ? If done incorrectly, this could cause problems with the panel.On the issue of TAKE-OFF SPEEDS DELETED.... I had seen it for three different situations a long time ago: 1) Rwy the aircraft is on and the rwy programmed in the FMC not the same (also known as being on the wrong rwy !), 2) attempting a takeoff from an incorrect point on the correct rwy, 3) when I was playing around with WET/DRY rwy setting (I don't use it anymore). I also seem to remember getting this message one other time in the past when I was on the correct rwy and properly positioned but I did not pursue since there are some inconsistencies in the scenery files for some airports. I don't remember the airport but it was in the U.S.Zach