Airspeed Indicator Problem

[Guest aviationhead]

Hi Guys,As this is my first post on this forum I would like to begin by thanking all of you for your help over the last number of years!I am noticing, over the last number of weeks (probably due to the drop in air temperatures in my area) that when flying in FSX my airspeed indicator will suddenly drop off to zero without prior warning. I have checked the the failure area and no failures are indicated and so I am left with only one logical conclusion, that the Pitot tubes are being frozen over and are causing my indicators to fail.With this in mind I have tried numerous 'anti-ice' configurations while in flight to see if I can solve the problem, all to no avail. I have even tried engaging full anti-ice prior to taking off, again with no improvement. I am using ASX to control my weather but I have also encountered the problem with some of the preset themes on the sim, all of which are the winter themes.I would be grateful if anyone could help me out with this one as it is quite frustrating that after going through the entire preflight stage with FS2Crew (45 mins) and spending time downloading charts etc that as soon as I get airborne I have to end the flight!!Perhaps this is a common FSX bug.Thanks in advance,

[Guest bluesky21]

What kind of weather do you usually fly in? It could be due to shifts in the wind, which don't happen very smoothly in FSX.

[phillroath 1]

You've probably already done this, but everytime I had those exact symptoms, Pitot Heat solved it. In some cases the acft switch did not seem to work, so I use the keyboard.Pitot Heat = Shift HOf course that's the default settings, did you reasign any controls?Phill

[Guest aviationhead]

Hi Guys,Apologies for the delayed response. I was out of the country all week.bluesky21; I fly using ASX and so I generally fly in the weather of the day.phillroath; I actually never thought of attempting a manual start of the pitot de-icing. In fact I have just tried it using the FSX theme of 'Heavy Snows' which is where I first found the problem, and it would appear that this corrects the issue!Thank you for your help!

[Tim Arnot 5]

RW, pitot icing can be quite insidious, since the effect is to seal the pitot tube at its current pressure. This means that the airspeed indicator will actually stay the same, so the pilot doesn't notice the problem. If the plane slows or speeds up, the indicator remains frozen. Because of the way the pitot static system works, an increase in altitude will show as an increase in airspeed, and a decrease in altitude shows as a decrease in airspeed (effectively behaving like an altimeter). This has resulted in a number of plane crashes when pilots didn't recognise what was happening. e.g. http://amelia.db.erau.edu/reports/ntsb/aar/AAR75-13.pdfIf the freezing is only partial, and the drain hole isn't blocked, the pitot pressure will gradually equalise and slowly drop towards zero (it may or may not reach zero). Not all pitot tubes have a condensation drain though. This is the only mode that FS (nearly) models, although it shows an immediate drop to zero.Pitot ice typically forms when flying through cloud or precipitation when the airframe temperature is below zero. The solution is to apply pitot heat while flying through clouds or rain. It is not normally applied on the ground (other than as part of the pre flight) due to the risk of burning out the element.