Hello people - I need some help with flying at high altitude IFR. I posted this in the ACtiveSky forum, but it's not really a problem with ActiveSky I don't think.Basically, I'm happily flying along, and I start to get a tail wind. The wind as about 80kts and because the air is moving in the same direction of the aircraft this stops the wind flowing over the wings in the right direction at the right speed. My speed is currently saying 156kts, GS is 345 and it's mach .46. Basause my my speed is 156 kts, my aircraft has pitched right up, and now requires flaps to be deployed to prevent my aircraft from stalling. I'm currently at FL340 above the Atlantic.This has happened to me before. I'm halfway through a flight in the new LDS767. It's happened to me in the past in the PMDG737.How do I prevent this? I'm sure IRL if you have a strong tail wind it doesn't cause the plane to stall and fall out of the sky! What should I do?Thanks in advance.

156 kts indicated airspeed? That is way too slow for cruising. The 737 should cruise about Mach .74 or higher. Maybe I'm not understanding what you are asking.

Well, the problem is that the air isn't hitting the front of my airplane at the speed it would, if there was no wind at all. If you are still - no forward or backwards motion (you would have to be in a helicopter!), and you had the wind hitting your back, you would effectivly have a minus speed. So if the iwnd was 10kts, you would be going -10kts as far as the aircraft is concerned. Because I have a tail wind of 80kts, I have 80kts worth of airflow LESS over the wings, and therefore I'm about to stall.I can't load a screenshot because this forum keeps saying the file is too big.

Gary, What Craig is telling you is that you're flying too slow. At that altitude in a 737 you should be at Mach .74 which would be approximately 260-270 kias. Are you at full throttle when you have this problem or are you trying to fly so slowly?

I too would like an answer for this issue - crosswind, headwind fine, but a good tailwind and fs physics (and I'll admit - logic) says you're stalling. Depending on the a/c sometimes autothrottle will firewall thrust to 'compenstate' until wind changes.I'd like to know what happens in the r/w - is this normal?regards,Mark3.2HT/1GIG/X700pro256

Thank you Mark.Steve - I wasn't flying too slowing when I firtst encountered the tailwind. I was flying at mach .795. When I encountered the tail wind, my airspeed dropped by 80kts straight away because the air was travelling in the same direction as me.Obviously, that means there is LESS air going over the WINGS. Result: STALL. Becuase my engines are pointed forward (like on most aircraft), there is less air to take in becuase the air is headed away from the aircraft by the time it gets to the intake. Therefore I loose speed.As Mark says, if you think about the dynamics of flight, you would have to question why this doesn't happen in reality.

It sounds like you need to turn on wind smoothing. This way the tailwind will increase somewhat gradually and the autothrottle will have time to increase thrust with the increasing tail wind to keep at at cruising speed. If you are using ActiveSky make sure that you enter and process your route. If you have a registered version of FSUIPC I think there is an option in there as well.Drew

hmm - there's an idea - I do have wind smoothing on but perhaps a longer transition time would alleviate this.thanks Drew I'll try that.regards,Mark3.2HT/1GIG/X700pro256

Gary,Googling around it seems to have to do with air density at typical turbojet cruise altitudes, not to mention realistic wind transitions, that prevent this. Vastly different story at very low altitude - tailwind component of 10knots is an A320's landing limit for example.Clearly fs seems to apply the same rules at fl370 as it does at 37 ft aglI hope somebody with more knowledge of fs and r/w winds aloft will pipe in here...regards,Mark3.2HT/1GIG/X700pro256

Mark & Drew - thanks for the replies.I've mnaged to turn off the winds at the high altitude. I was looking around FSUIPC and I don't think I changed anything but when I clicked OK the wind went down to zero and I was able to pick up some speed. I hope wind still exists at lower altitude. I also turned of the WINDS ALOFT in ActiveSky - but as I say none of these changes seemed to work straight away.I think I have the wind smoothing set at 5kts/second. I don't know if that's a realistic value of not.

Hi Gary and Mark,First I'll address Gary...I agree with Drew as posted above that you should process your flight plan through Active Sky before your flight as this allows AS2004 to smooth your wind transitions. A 5kt/sec value should be fine for most flying in FS or you can even decrease it to 2 or 3 if you want. Your problem is extreme, but not unheard of in MSFS which has a problem with winds aloft transitions.When an aircraft encounters a tailwind, it should eventually equalize to its regular IAS with the same power setting because the transitions should be gradual enough for the aircraft to respond. In your jet, the autothrottles should increase to compensate for the IAS loss, but I've never seen a firewall compensation. In the real world, it is highly unlikely to encounter an istantaneous 80kt+ wind shift...it is usually gradual over distance. As far as the aircraft is concerned, it doesn't now if the wind is blowing or not (only the pilot does!!), it only needs a proper airspeed to stay in the air. Thus, as a tailwind increases, only the groundspeed should change as the aircraft equalizes to flow with the new wind (much as a boat travelling at 10kts with a 5kt current still indicates 10kts in the water but has a velocity of 15kts relative to the shore)As for Mark,As I stated above, instantaneous wind changes are very rare...almost non-existant in the real world in clear air (Under Thunderstorms can cause shears due to a microburst). Encounters are referred to as Clear Air Turbulence and we have seen the results of violent shears very rarely, thank goodness.Winds aloft usually shift gradually over distance...unfortunately MSFS does not simulate this very well. FSUIPC can help this FS shortfall, as well as Active Sky 2004. With this gradual shift, aircraft are more than capable to compensate.As for the maximum tailwind components for landing aircraft (all aircraft have a maximum), this is due to the fact that the greater the tailwind component during landing, the longer the runway rollout. The longer the rollout, the greater the chance of overrunning the runway.Here is an example:An airport has a runway 18/36. Winds are 180 at 10kts. Our aircraft lands at an IAS of about 130kts lets say.So...if we are approaching RWY 18 with the wind on our nose (into the wind) we will land at an Airspeed of 130kts, but the groundspeed would only be 120kts (130kts-10kts), thus a nice short rollout. Taking off into the wind does the same by reducing the runway usage on the takeoff run.Then...if we are approaching RWY 36 with a tailwind, we still land at an Airspeed of 130kts, but now our Groundspeed is now 140kts (130kts+10kts, 20kts faster than the other direction, thus we must use much more runway to slow. Takeoff with a tailwind also uses MUCH more runway...So that is why we are encouraged to land and takeoff into the wind.Hope this helps a little!!

Thanks Mate - I'm pleased someone understands my problem. I was beginning to think there must be something wrong with my setup.Anyway - I think you're saying that if I change the wind smoothing to 2 or 3 (actually, I've changed it to 1), that should sort itself out as it gives the a/c more time to adjust - right?Anyway - not that I've changed it hopefully I make make use of tailwinds. I'll also try loading my plan in ActiveSky.Thanks!

ditto :) regards,Mark3.2HT/1GIG/X700pro256

Glad you guys were able to understand my rambling!! :-)I use ActiveSky all the time and have never encountered any wind shift problems since they we able to enable wind smoothing along with FSUIPC. The secret is processing that flight plan in ActiveSky!!Hope you have success!!