Speed indicator stops soon after take off

Hello. I fly 737 and 747 and David Maltby Comet and Trident.

I fly IFR and use auto pilot soon after take off.

All is fine sometimes, but often as not the speed indicator will suddenly return to zero, not long into the flight, and I have to kill auto throttle and fly manually.

However I still have no idea what my speed is. unless I am using FS Commander, an add on linked to fsx , and that shows some data including indicated air speed. I rely on that

Funny thing is, when I am making the descent the speed indicator in the aircraft panel comes back on and stays on for the landing!

 

It's as though I might be at the computers power limit, and something has to give, so the speed dial stops working?

Is it a fsx problem or a computer power problem do you think.

 

I've checked. " failures" and I've got nothing set there to fail.

 

In confg file I see there is a true/false option for indicated air speed. I had it set at false. Is that relevant do you think?

 

Thanks

Are you turning on your Pitot tube heat before you take off?

To expand a bit on what Mr. Zippy said, a pitot tube (receives ram air pressure to drive the airspeed indicator) can ice up, especially when there's a lot of moisture in the air and it's cold outside. And that's what the pitot heat is designed to deal with. So if there are clouds and it's cold, you'll want it on. And if you're going to jet altitudes you'll want it on anytime.

To expand a bit on what Mr. Zippy said, a pitot tube (receives ram air pressure to drive the airspeed indicator) can ice up, especially when there's a lot of moisture in the air and it's cold outside. And that's what the pitot heat is designed to deal with. So if there are clouds and it's cold, you'll want it on. And if you're going to jet altitudes you'll want it on anytime.

 

Thanks for this. I am not specifically aware that I am doing that. However I get a "ice" light come on and I've found some switches or buttons , depending on model , that when I activate them the "ice " light goes out.

Is that it?

If not where can I find out what the switch is please.

If in doubt where the switch is press shift plus h to turn on pitot heat. The switches you were turning on to get rid of the ice light are deicing switches for wings/prop boots.

I don't know anything about those specific aircraft that you listed, but it will be a switch somewhere labeled Pitot Heat, and it may or may not have a panel light associated with it. It should be somewhere on the instrument panel, or perhaps in the overhead panel, and probably isn't the same for all those aircraft. The "Ice" light probably indicates wing icing, OR some aircraft have some lights on the wing that, when turned on, let the pilot look to see if ice is accumulating on the wings -- I don't know which you may be seeing.

Thank you guys. I think that was it. The pitot tube heater.

I found the switch in the 737 overhead, and I have a switch in PDF for 747.

 

One more please. How do I go back to cold Nd dark start when first starting fsx

Thanks

Thank you guys. I think that was it. The pitot tube heater.

I found the switch in the 737 overhead, and I have a switch in PDF for 747.

 

One more please. How do I go back to cold Nd dark start when first starting fsx

Thanks

 

Start a flight, I would use a default aircraft like the Baron58. Plant it at an airport in your time zone. Turn off the engines and all electrical. Leave the avionics switch and pivot switch on. Set your parking brake. Now hit your semicolon key. Name this flight as your default flight. Check the box that says " Save as Default flight.". Save it!

Edited May 13, 2020 by mrzippy

Thanks Done that with A320.

Getting there😀