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Not able to climb and speed is suddenly dropping


aprodigy
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Experienced this a couple of times yesterday at different flight levels.

 

Speed is around .74, flight level at around FL300, plane is all leveled and up in the air without problems for around an hour. Tried then to climb a bit further but it resulted in nothing happening. The outside view however looked like this and the plane slowly began losing speed and height more and more.

 

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I tried to catch the plane at FL240 but didn't succeed either. The plane stayed at around 140kts and was still losing height. Then all of a sudden, the plane leveled itself in the outside view, speed rose again, i tried to climb again but to no avail. Tried a lot of things (checked for speed brake, tried anti ice et cetera).

 

FilbertFlies experienced somewhat of the same situation in his latest video at around 1h50. It's absolutely possible that I've done something wrong or didn't notice something, i.e. an arm chair pilot error happening but it was still a very strange situation I could not explain to myself.

 

Pebkac or bug? ;)

 

 

 

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A number of people have reported increasing weight of the aircraft which is likely the sim's icing effects. After I turned off the icing effects in the sim ("visual only"} the aircraft behaved normally and was able to climb and maintain altitude.

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vor 1 hour , John2 sagte:

A number of people have reported increasing weight of the aircraft which is likely the sim's icing effects. After I turned off the icing effects in the sim ("visual only"} the aircraft behaved normally and was able to climb and maintain altitude.

 

Thank you for the hint - this might be indeed an idea to try out.

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Also, once you are too slow, you will not be able to recover unless you actually increase speed by pitching down (and of course loosing altitude). Once you are below a certain speed and still try to hold the altitude, your aircraft will not have enough power to overcome the drag induced by the high pitch.

 

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vor 9 Minuten, HighFlyer51 sagte:

Also, once you are too slow, you will not be able to recover unless you actually increase speed by pitching down (and of course loosing altitude). Once you are below a certain speed and still try to hold the altitude, your aircraft will not have enough power to overcome the drag induced by the high pitch.

 

 

Alright, thank you. Is that specific to certain aircrafts or aircraft types? I would have expected the aircraft to easily climb at that speed since much more than .74 is not advisable but I guess I can find that out in the accompanying performance guide, uh?

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45 minutes ago, aprodigy said:

 

Alright, thank you. Is that specific to certain aircrafts or aircraft types? I would have expected the aircraft to easily climb at that speed since much more than .74 is not advisable but I guess I can find that out in the accompanying performance guide, uh?

It's a general thing with aircraft. There's a minimum-drag speed for every aircraft, below which going slower means needing more power to maintain speed.

 

This speed corresponds to the minimum hold speed, which is in the VSpeeds PDF that comes with in the Documentation section.

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The pause bug was already discussed here several times - pausing the sim (not active pause) leads to a massive performance drop afterwards.

Did you pause the game with escape key right before this happened?

 

Aerosoft acknowledged that there was an issue with pause. This is intermittent for me, I have had it a few times (~3-4 times). Try to avoid pausing with ESC key.

 

 

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Vor 1 Stunde, oisk sagte:

Did you pause the game with escape key right before this happened?

 

No I didn't. I was up in the air flying at .74 at FL300 as ATC told me to rise to FL380 (ignore that fact; FL380 is not tha maximum height for this plane so I just tried). I put the throttle lever to climb and switched to speed with a maximum set of around .78 and then the plane speed went slowly but surely down and it started to fall. Since ATC constantly reminded me to rise back again, I tried all I could to get up again but didn't have any success so I asked ATC for a lower FL. First FL280, then even FL240.

 

That's when I took both of the screenshots above. In the FilbertFlies video I mentioned above they were discussing this issue, too because he was facing the exact same issue but I couldn't really get around what they were assuming and talking about. That's when I decided to ask about this in here because I'm not sure what I could do to get the plane rising while already at .74 apart trying to speed up more in order to get the plane higher.

 

I will try the "visual ice" option as soon as I get a chance. Since it happened to me two or three times now I'm quite interested to find out what this is all about.

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On 3.4.2021 at 15:55, JRBarrett sagte:

Yes, “visual only” icing is strongly recommended. The MSFS icing effect is overdone. It adds weight to the airplane.

Even the "Visual Icing" setting is not preventing one from seeing this increase of weight.  Just happened again....
Had live weather ON, FL370, AntI Ice  OFF and in (stable) cruise for over an hour, when it happened. No ICE warning, nothing

No increase in the DEVs menue   OPTIONS/ Visual Icing slider either

 

Oliver

 

 

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vor 3 Stunden , JetNoise sagte:

Even the "Visual Icing" setting is not preventing one from seeing this increase of weight.

 

Ya, I guess the same is happening here and again:

 

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I was on a flight from KJFK to KMIA today. Everything was smooth at FL360 and at .73-.74 - N1 was at around 80-81 when the plane suddenly after about an hour or so lost speed down to around 180KTS when I realized what was happening (wind hadn't changed, though). I catched the plane, though by pushing the levers to their max (N1 at 91) but the plane just stuck around at around 180KTS and was barely gaining any speed back even though N1 was at 90+ aleady. If ATC would ask me to rise to FL380 I would have not gotten there, even in climb mode since it pushes N1 only +2 points more - I probably would have lost much more speed just by trying that like the day before yesterday when I first reported it.

 

I then put the plane back to climb (N1 at around 93+) and after maybe seven or eight minutes or so I was finally back at .74:

 

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I put the icing effects to visual only, too now but that doesn't seem to be the issue at stake here. I really don't know if that's the expected behavour. I've also rewatched FlibertFlies video I mentioned abobe - he also had the icing effects to visual only. They seem to have suspected that he didn't realize that he was losing speed beforehand. I did check the display readings constantly though.

 

And this other topic kind off explains what I'm somewhat experiencing. when it comes to climbing.

 

 

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Same for me today. Climbing to FL380 with Mac 0.66 and A/P on Speed / Nav. from TFFR to MDCP, nice weather, no icing ,  Passing FL300 ( after about 15 mn  flying), throttles stable on CLIMB detent, trim stab was about 4,5/5 THEN SUDDENLY  the speed dropped >> 180 its >> 160 its  and the pitch get up with a stab trim up to >9... resulting in a stall profile.

Disconnected AP, trying to get out from the stall, pushing the yoke down trying to get more speed, loosing some 10.000 ft....OK got a 250 its speed at 25.000 ft manually , stable pitch

 when reconnecting the AP >> the pitch suddenly move up with a + 30° and of course stall again....

This seems to be a recurrent issue due to weight/ power inbalance above 25.000 ft. and A/P is not functioning after stall recovery.

something Aerosoft have to work out I think. AND THIS IS NOT DUE TO ICING EFFECT AT ALL. 

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vor 7 Minuten, Patrick Paris 75 sagte:

above 25.000 ft

 

I agree. Around or below FL200 I could not replicate the issue we're facing here but I'm still trying to make any sense out of it all to be honest. But the situation you're describing is the exact same I have been experiencing.

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13 minutes ago, Patrick Paris 75 said:

Same for me today. Climbing to FL380 with Mac 0.66 and A/P on Speed / Nav. from TFFR to MDCP, nice weather, no icing ,  Passing FL300 ( after about 15 mn  flying),<...>

 

If you try climbing to FL380 with Mach .66 you will definitely get on the wrong side of the drag/power curve at some point and can even stall. Keep a minimum of M.74 up to FL360 and I suggest M.77 after that for a solid margin at all weights.

 

Just for future flights, not saying that is what happened on your flight. Around FL300 you should still have some margin with M.66, but not for much longer/higher above FL300.

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20 hours ago, aprodigy said:

I catched the plane, though by pushing the levers to their max (N1 at 91) but the plane just stuck around at around 180KTS and was barely gaining any speed back even though N1 was at 90+ aleady.

Adding more power will not help, you need to pitch down and descend to gain airspeed when you’re that slow. When you’re back at around 290 knots you can start climbing back up again. 
 

There is also an issue when spoilers can be deployed without showing it on the lever in the cockpit. It can happen if you have the axis assigned and pause the game AFAIK. Sometimes worth to just move the lever to make sure they’re really retracted. 

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