Airspeed suddenly goes to zero inflight

[Skywatcher 133]

4 hours ago, BigGiraffe said:

Good Evening,

The weather I'm using is FS Global Real Weather.  And, thinking about it, that might be about the time I started to notice the airspeed dropping off as described.  Prior to that, I was using FSRealWX Lite.

Kurt

Ok, it's starting to look like it's the icing injected into the sim from these programs that may cause the issues. I've had the issue forever but also used ASE forever! lol

[edetroit 933]

3 hours ago, Skywatcher said:

Ok, it's starting to look like it's the icing injected into the sim from these programs that may cause the issues. I've had the issue forever but also used ASE forever! lol

I would have to agree with you Mark. I think the only way to fix this would be to switch of icing in the options section of ASE.

Having said that it does make me smile when I am in my lazy man's aircraft (with VNAV)  and I have to be quick to switch off the auto throttle get the throttles back to climb power and watch my pitch for a bit.....keeps one on one's toes.

I smile even more when I am flying with manual throttle control....and I'm thinking...is that the best you've got. 😁 

[Skywatcher 133]

35 minutes ago, edetroit said:

I would have to agree with you Mark. I think the only way to fix this would be to switch of icing in the options section of ASE.

Having said that it does make me smile when I am in my lazy man's aircraft (with VNAV)  and I have to be quick to switch off the auto throttle get the throttles back to climb power and watch my pitch for a bit.....keeps one on one's toes.

I smile even more when I am flying with manual throttle control....and I'm thinking...is that the best you've got. 😁 

Haha, yeah, iFly 737 for me and the issue screws things up pretty quickly. I mentioned earlier in the thread I've turned off icing now as you mentioned, it's the only guaranteed fix. Been flying with icing off for a while now. It's no great loss but it certainly is great to not have to put up with the issues.

I'll just pick and choose when I think I would need to flick the icing switches to not miss the pleasures of flicking them on and off. lol

Edited April 9, 2019 by Skywatcher

[Skywatcher 133]

Oh dear! lol

So I'm doing a flight, I'm at cruise and type my post above. Getting close to decent, I go back to FS. I check the destination weather report to see what to expect. The report states "Severe Icing!!!" Huh??? lol

I'm thinking this can't be good. I turn on the icing switches. I know they are totally useless but it's the right thing to do. I start descent and then just wait...and wait...and yep, sure enough, there goes the airspeed again!

I start thinking, "Why and how could this have happened?"

I'm no icing expert, haven't even read the icing download provided earlier but this is what appears to have occurred from what I can make of everything at this stage.

Turning icing off in ASE is for cloud icing. I imagine icing conditions are brought on by cloud icing and "general" icing. While cloud icing can and was turned off in ASE, I'm guessing I probably experienced "general" icing which has no off switch in ASE. I'm not sure if there is a way to fully turn off all icing conditions in FS9. I did a quick scan of the FS9.cfg, found nothing there. Will work on this a little more.

Since turning off cloud icing in ASE, I can certainly suggest I have had faaaaar less airspeed problems than when it was on. It may also be the case that cloud icing causes the less severe icing warnings which are also the more frequent ones.

From the above, I can now conclude icing is still in FS9 and it's likely a "general" form of icing which occurs. Turning cloud icing off in ASE certainly appears to eliminate most of the icing problems but certainly not all.

I love how FS always somehow manages to throw a surprise at you! I'm going to win in the end. May take another decade or two but I will win. haha

 

 

Edited April 9, 2019 by Skywatcher

[PebbleBeach 120]

We use an add on module that actually does respond to icing reports and injects this in the simulation.

Mitch

[John Hinson 22]

On 4/9/2019 at 10:15 AM, Skywatcher said:

I'm thinking this can't be good. I turn on the icing switches. I know they are totally useless but it's the right thing to do. I start descent and then just wait...and wait...and yep, sure enough, there goes the airspeed again!

I start thinking, "Why and how could this have happened?"

I'm no icing expert, haven't even read the icing download provided earlier but this is what appears to have occurred from what I can make of everything at this stage.

Turning icing off in ASE is for cloud icing. I imagine icing conditions are brought on by cloud icing and "general" icing. While cloud icing can and was turned off in ASE, I'm guessing I probably experienced "general" icing which has no off switch in ASE. I'm not sure if there is a way to fully turn off all icing conditions in FS9. I did a quick scan of the FS9.cfg, found nothing there. Will work on this a little more.

Since turning off cloud icing in ASE, I can certainly suggest I have had faaaaar less airspeed problems than when it was on. It may also be the case that cloud icing causes the less severe icing warnings which are also the more frequent ones.

From the above, I can now conclude icing is still in FS9 and it's likely a "general" form of icing which occurs. Turning cloud icing off in ASE certainly appears to eliminate most of the icing problems but certainly not all.

I am inclined to agree with you, since I turned off the cloud icing options in ASE, the occurrences seem less but definitely not eliminated. At any rate, they seem to occur whichever of three weather programmes I use.

However, I would dispute your comment that the icing switches are totally useless. This is not so, but you need to deploy them at the right time for effect, i.e. when the OAT gets down to around zero degrees. Certainly on propeller planes (95% of what I fly,in my imaginary world are large prop-driven airliners) the switches are very effective. But if you forget to deploy them untul you notice airspeed dropping dramatically, the slow speed they take effect could result in falling out of the sky. That in itself may be fairly realistic.

However, I agree those switches have no effect whatsoever on the issue discussed in this thread. The Pitot Heat is surely what is critical here but something else must be happening.

Is it not possible that it is not an ice problem at all, but something in the weather engine dropping the air pressure temporarily to zero? Pitot-static instruments detect air pressure to give the correct speed and altitude reading.

John

Edited April 13, 2019 by John Hinson

[ronzie 21]

Airspeed indicators that use pitot air inputs also use that static ports pressures to subtract from the ram port pressures to get the net dynamic air pressure relating to air speed. Check your barometer/altitude readings when this happens.

How about control surface (wing) deicers. Are they on?

 

[Skywatcher 133]

14 hours ago, John Hinson said:

However, I would dispute your comment that the icing switches are totally useless. This is not so, but you need to deploy them at the right time for effect, i.e. when the OAT gets down to around zero degrees. Certainly on propeller planes (95% of what I fly,in my imaginary world are large prop-driven airliners) the switches are very effective.

Ok, I've fllown the iFly 737 exclusively for a while now. May be a difference between the icing switches. The other thing which may be an issue with me is I use the no longer supported iFly panel. It's possible there may be a bug or two using this panel.

However, I'm certain I have experienced this same problem in the past with other aircraft so I consider the above possibilities unlikely.

14 hours ago, John Hinson said:

Is it not possible that it is not an ice problem at all, but something in the weather engine dropping the air pressure temporarily to zero?

I believe everything points to something between the weather engine and FS not functioning as it should. What, where, how and why, I have no idea. At least this thread is here. If we have enough pieces to the jigsaw maybe eventually we can put it together.

ronzie, I have everything on.

[John Hinson 22]

12 hours ago, ronzie said:

Airspeed indicators that use pitot air inputs also use that static ports pressures to subtract from the ram port pressures to get the net dynamic air pressure relating to air speed. Check your barometer/altitude readings when this happens.

How about control surface (wing) deicers. Are they on?

Barometer and altitide indications are fine, but we do not know of course how Microsoft modelled things. Much seems remarkably accurate but other things could be bodged.

Wing de-icers always on for me too.

John

[Skywatcher 133]

Last flight I had trace icing warnings. In this situation, sometimes I have the airspeed problem, sometimes I don't. The trace icing seems to actually trigger as it should and quite randomly as you would expect with a trace icing warning.

During the descent of my last flight I had the airspeed problem twice. The second airspeed issue occurred with TAT at +5 Celsius. Anyhow, just adding some information which may or may not be useful at some stage.

[BigGiraffe 0]

Hello,

I set FSUIPC to supress cloud icing and have not seen the "airspeed goes to zero" problem since then. 

This also cured an additional problem I was having -- The Fokker F-27 I was using would shut down engines during cruise, regardless of using anti-icing systems.  I didn't connect the engine shut-down with icing until a day or two ago.

Best regards,

Kurt