Pitot covered (by icing), No ground speed displayed

[skyview_user]

Hi Dynon, when the pitot tube is covered, no ground speed is available. But SkyView has it. Why do I need to take my 50 $ phone to get ground speed displayed?

 

[DBRV10]

From the manual;

The SkyView artificial horizon display (attitude) is generated via a complex algorithm using a multitude of sensors as described in Table 1. In normal operation, SkyView uses airspeed to provide superior attitude accuracy. Should airspeed become unavailable due to inadvertent blockage of the pitot system, GPS ground speed will be used as an attitude aid. CHECK PITOT HEAT will be annunciated on the PFD when this mode is in effect.

and this

In the event of airspeed loss (due to icing or other blockage) an accurate attitude is maintained if there is an accurate GPS ground speed source. When in this mode, a CHECK PITOT HEAT message is displayed on the PFD and the ground speed is displayed below the indicated airspeed (IAS). If the connectivity with the GPS fails while in this mode, the attitude continues to be displayed, using the last known GPS ground speed as a reference. This mode is flagged on the horizon with a yellow CROSS CHECK ATTITUDE message. In the very rare case that this sequence of events occurs, the ADAHRS’ attitude accuracy is reduced; use other references in the aircraft to cross-check against the SkyView display.

Having said that this is what used to happen, and the IAS box changed to Magenta

Added: GPS assist mode to ADAHRS algorithm. GPS ground speed is automatically substituted for airspeed when the System detects that the airspeed indication has failed (usually because of an iced, blocked, or otherwise disconnected pitot). When this happens, the PFD annunciates that its attitude indication is in a “GPS Assist” mode. The EFIS display also shows GPS ground speed next to the failed airspeed indication to help the pilot maintain situational awareness. Most importantly, when in GPS Assist mode, the attitude provided by Dynon Avionics PFD continues to be accurate.

I have never had an in flight blockage with SV/HDX, but I copped a bug years ago with the D100/D180 and it immediately came up with GPS ASSIST and magenta everything as the wheels left the runway. We were VFR on this leg so we continued.

 

[skyview_user]

Thanks, David. Very interesting. The behaviour on my SkyView (not the HDX version) was unfortunately different. Hm....

 

[DBRV10]

Thanks, David. Very interesting. The behaviour on my SkyView (not the HDX version) was unfortunately different. Hm....

You might want to test it some more. Put the pitot cover on and do a run down the runway, heck....I would take it for a fly, so long as there were no flapping tags to destroy things. You should be capable of flying without airspeed. If you are not confident in that perhaps stay on the runway.

 

[jakej]

does anything fly without airspeed ?

 

[Dynon]

So the attitude will keep working, using GPS speed as its aiding source. IAS will be zero. It isn't replaced to not cause misleading indications. GPS isn't airspeed, and can be quite different based on wind. However, just under the IAS tape, ground speed is GPS speed, and that will remain active and can act as a proxy for general speed information.

 

[skyview_user]

Thanks for the answers. Maybe I overlooked ground speed. Next time I'll have a look on that.