My PFD air speed display resets....

[Nick1150]

Hi,

It happened twice, and I know that most probably it is something in my setup or something that has to do with my flight plans settings, but I do not know how to fix this, so here it goes...

Both times it happened after or before (I am onot sure) the last STAR of the flight plan, when the ATC gave me a specific HDG and left LNAV/VNAV to HDG mode. After that my PFD airspeed display resets to zero (30 knots to be more specific) and the A/T doesnot operate and does not listen any speed I input.

After the usual approach procedures, when the aircraft is on final the airspeed display comes back again to the real speed.

Note: During all this, all other information including the altitude tape work perfectly.

Any idea ?

[yoss]

Just guess

Are you engaging pitot heating?
You should do that
Otherwice pitot tubes freezing and wierd speed anhd altitude values displayed
Whe you are low again on approach- -temperature raising , the pitot not blocked by ice anymore and all cames to normal
This phenomina is simulated

[Nick1150]

If this is true, I am amazed !!!

In fact I do not engage pilot heating, but really could this be true ?

Just asking...

[yoss]

Thats what happends in real life ,Nick

I have somewhere Discovery channel video abot B767 crached in the see , at night , becouse the ground crew forgot to remove the maskentapes from pitot tubes
The perfectly operational aircraft with expierienced crew crached only becouse they lost their altitude and speed indications by night over the see

Real storry with many lives lost

[Nick1150]

Thanks yoss,

I will try it and let you know

[leilson]

If this is true, I am amazed !!!

In fact I do not engage pilot heating, but really could this be true ?

Just asking...

You should always engage probe heat on ( pitots heat), just after starting both engines . The sequence before initiating taxi is eng gen on , probe heat on , eng start switches cont , apu off , recall, flaps 5 .

[Nick1150]

Thanks for the response,

Actually I do not have an overhead yet, but I have an 11 switch panel located on my pedestal box instead connected with a Leo Bodnard card for that reason. All switches are assigned mainly for the lighting panel and autostart, shutdown of both engines plus generators a and b....



Unfortunately the switches are all occupied, I will have to exchange a switch with pilot heat on/off, until I add more switches in this panel.

Thanks,

[saabpilot]

I have the very same symptoms in the B737 PM PFD - Speed suddenly goes to zero (30) and after 30 sec it is back to normal again.
This happens on 1-2 hr flights randomly - mostly only once per flight.
All anti-icing and probe heat is on, so that is not the problem.

Full Magenta suit incl. pmSystems - build 480.

Bjorn

[Thomas Richter]

I have the very same symptoms in the B737 PM PFD - Speed suddenly goes to zero (30) and after 30 sec it is back to normal again.
This happens on 1-2 hr flights randomly - mostly only once per flight.
All anti-icing and probe heat is on, so that is not the problem.

Full Magenta suit incl. pmSystems - build 480.

Bjorn

Hi

It is the only reason when the Speed tape fails.
Just check it is in FS really set to ON, may be pmSystems doesn't switch it correct in FS to ON.

[leilson]

I have the very same symptoms in the B737 PM PFD - Speed suddenly goes to zero (30) and after 30 sec it is back to normal again.
This happens on 1-2 hr flights randomly - mostly only once per flight.
All anti-icing and probe heat is on, so that is not the problem.

Full Magenta suit incl. pmSystems - build 480.

Bjorn

Try one thing: set OAT to 25 a 30 degrees Centigrades before takeoff . I´m saying this because this was happening in an friend of mine A320 simulator and work out.