More on the "Dodgy" VNav Descent

[FOD 23]

{Steven

[Guest Phoenix5]

Thanks John.

[Guest Mike Phyrio]

I gotta tell you guys that I just love the 757 just the way it is. I think that sort of thing happens when you get to know how something works and what its flaws (however you define those) are and how to deal with them.I figure that if a plane will do the CIVET5 or the SEAVU1 into LAX, then it can do just about anything.....and, once again, the PMDG 737 won't do it.I'm a little hesitant to install 1.3 because I'm scared of losing what I've already got. But........I suppose I'll have to.......one of these times............

[Porthos 9]

All, my 2.2 cents worth (GST inc for those who live in OZ)True the 757 FMS is not exactly the most schmick piece of kit around however, until one item is enabled in the FMS then the VNAV wont be as accurate as it might be (my opinion only of course)To enable the forecast winds in the FMS input would give a better chance of the aircraft maintaining VNAV path as IRL.The forecast winds assist the FMS to predict TOD and hence VNAV path.If the forecast winds are not enabled the FMS sees nil wind. If it encounters anything other than still air it is going to be somewhat askew trying to get to a height requirement of make a level on descent or even maintain a CDA path to the runway.Now unless I have missed something or my FMS is one surplanted from an Airbus the forecast wind is not enabled in the PSS bird (Steve that is correct is it not?)Having said that I have made a few flights with v1.3 and find it rock solid (ahem... after my initial HOLD problem that is which a reinstall fixed... my problem I think)BTW install 1.3 (fresh install after an unistall).______________________________________Rob YMA002 - Compass Airlines Australia - a new direction!

[Jim Harnes 13]

FMS wind entry would be a terrific addition to the 757 and the 777!Jim Harnes

[MOFF 1]

Not only the entry of winds, but much more the calculation of wind :-)Steffen Rabenau

[philbrown 9]

I still believe this is a bug, and not a "feature".Compare the two pictures:http://forums.avsim.net/user_files/177352.jpghttp://forums.avsim.net/user_files/177354.jpgThe 1st one is VNAV descent with RESTU in the route, 2nd one without RESTU (although I've turned on the WPT feature so we know where it is).I'm at exactly the same point in both pictures, yet there is a 3500ft differene between the altitudes. The green bar also tells you that I'm clearly descending too quickly on the 1st shot, and I'm more or less bang on on the 2nd.Why is there such a massive difference between having RESTU in the route and not having it? It seems it's just a incorrect formula in the FMC for calculating altitudes at waypoints between TOD and EOD.

[Porthos 9]

Steffan the FMS cannot calculate the winds unless the operator is engaged in dynamic wind uploading. Not many operators are.Crews enter the forecast winds on the ground before departure generally and update them if they get an update.some of the more modern aircraft with progressive operators are having up to date winds uplinked via ACARS or CPDLC into the FMS. Otherwise its only forecast...the FMS does basic calc from that for VNAV path.______________________________________Rob YMA002 - Compass Airlines Australia - a new direction!