I use vnav and fmc on other a/c like the cs767 etc, so am not new to the concepts involved.But i am new to this md80.i take off engage lnav and that works fine,but when i engage vnav , the climb rate is about 400fpm or less, and the plane starts to slow down. What vnav does with speed and altitude does not match fmc settings in the least bit.Any help with this

good support on the coolsky support forum -http://s80.flight1.net/forums/--

Hi WarpAir; Selecting VNAV after take-off assumes you are using FMS data to control pitch and thrust. If you didn't program this into the FMC you aren't going to get a correct vertical profile.

Hi WarpAir; Selecting VNAV after take-off assumes you are using FMS data to control pitch and thrust. If you didn't program this into the FMC you aren't going to get a correct vertical profile.

Hi thanks for the replies.As i understand it, the way to get fmc to fly vnav is to give it a vertical and lateral profile on legs page.What exactly or how exactly do i get fmc to use pitch and thrust.The plane is behaving exactly like you say , it bahaves as if vnav has no control over pitch or thrust, so how do i get vnav to control pitch and thrust on md80, other than all the perf and flight plan data i entered in fmc.I have input all neccesary data in fmc, and thrust rating is set to Climb mode before i engage vnav climb, just as the manual says. Baffles me what could be missing, as i am not new to fmc concept or vnav.

Warp,As noted by Scoob, head over to the Coolsky support forum:http://s80.flight1.net/forums/You'll find a wealth of information and a group of knowlegable S80 fliers always on hand. There's also a decent tutorial flight stickied in the relevant section of the forums.

Warp,As noted by Scoob, head over to the Coolsky support forum:http://s80.flight1.net/forums/You'll find a wealth of information and a group of knowlegable S80 fliers always on hand. There's also a decent tutorial flight stickied in the relevant section of the forums.

been there and done search with no usefull result. Its not that i dont know how to use fmc or vnav.in fact vnav worked the very first time i flew. dont know what has changed

been there and done search with no usefull result. Its not that i dont know how to use fmc or vnav.in fact vnav worked the very first time i flew. dont know what has changed

Did you ask the same question over there? I'm sure you'll get plenty of suggestions.Could always try an unistall and re-install of the aircraft if all else fails.

Did you ask the same question over there? I'm sure you'll get plenty of suggestions.Could always try an unistall and re-install of the aircraft if all else fails.

Assuming you have vertical information in the FMS you will also need to set the ALT knob to the altitude you wang to initially climb to, and then pull the knob out to arm it (I think it's a right click but I could be wrong). Following that I would go to the forums, I have always found them helpful there.Bruce.

Assuming you have vertical information in the FMS you will also need to set the ALT knob to the altitude you wang to initially climb to, and then pull the knob out to arm it (I think it's a right click but I could be wrong). Following that I would go to the forums, I have always found them helpful there.Bruce.

Thanks , sounds like you know the super80 well, not pulling/pushing that silly knob nearly crashed me on descent a few times, so i learnt that hard way. If you just set and dont do the knob the a/c just keep going to the ground.I take off then engage AP speed, heading and altitude, lnav works ok, but as soon as i hit vnav, speed starts to reduce till the a/c stalls, even though econ speed in fmc climb page reads 300 knots.In any case i have reinstalled as suggested, yet to try again, just chnaged from vista64 to win7 , so maybe a reinstall could be the issue. but then who knows.thanks

The learning curve with new plane is hardly ever fun for me, but once you get there its ok.Just figured the problem with VNAV was that i pull the throttle back to idle when i engage Auto Throttle, but AP speed control works perfect with throttle in idle, but vnav speed control fails.So solution is to push throttle forward and leave it there for vnav speed to workThanks for the help guys, shame i did not find this out before reinstalling the a/c and fsx sp1 and sp2.Its learning curve that mostly puts me off buying new a/c in fsx not always the cash.