Flight to Earls Colne

[AlanB]

I flew from Brimpton to Earls Colne with PilotAware and have an observation which I need cross checking please.

I fly an Europa with a AVMAP EK V as my main GPS display and I also had the PilotAware running with a GPS Dongle and therefore providing the GPS position information and traffic alert to RunwayHD on an iPAD.

On both the outbound and inbound flights the Track on the iPAD was some 5Nm behind the position track on the AVMAP, constantly while moving. When stationary on the ground there was no difference.

I cross checked the position with me overflying various waypoints, Wycombe Air Park, Stoken Church Mast, Bovingdon VOR, Stapleford and the AVMAP was spot on but the iPAD definitely 5Nm behind.

Need to cross check further with the iPAD inbuilt GPS and a blue tooth GPS to see if I get the same results but is anyone else noticing this kind of difference?

Any explanation?

[Admin]

Very strange.
Lets confirm a few things
Firstly, is runwayhd taking its position information from PAW or the internal iPAD GPS ?
(Just checked, and this is configurable in runwayhd)

When stationary, were the two in agreement, or offset ?

I am trying to ascertain if there is a constant offset of 5nm, or whether there is a latency.
If there is latency, then after you completed your journey there should have benn a catching up of the positions

Thx
Lee

[AlanB]

Position from PAW I made that selection.

At the waypoints at LAM and BNN where there were changes in direction the Runway HD was definitely behind and stillon the inbound track when my Autopilt had turned onto the new heading and the AVMAp was showing new outbound track.

Runway HD caught up and then turned at the the way point but after the actual event and continued on the outbound leg with exactly the same track but delayed.

As I was concentrating on the landing and taxi I didn't look at Runwy HD during that phase just noticed on stopping that both GPS were now aligned

As the tracks overlayed it definitely looked like lag and and not position inaccuracy.

Need to explore further.

[Tony Crome]

HI

<I think> I noticed a similar occurrence of false GPS position with RunwayHD when using PAW.  Only a brief trial flight  and I was solo so not too much time to investigate.

Also I have posted about ADS-B traffic flicking continuously off then on. Perhaps the wifi is interfering with the iPad/Runway HD in some way ?

Early days and I need to do some more flight testing.

Tony

[Admin]

Is this specific to RunwayHD, or is anybody seeing similar behavior in the other tools ?

[Tony Crome]

Tried RunwayHD in the cockpit again using a better power source - the pi red light now on throughout. All working well at home.

When trying in the cockpit though I still get the ADS-B returns cycling on/off regularly about every 2 seconds, usually with the message 'loss of Flarm data'. This occurs  even on the ground with all aircraft supply switched off.
During the 30 minute flight there was no loss of GPS position on RunwayHD.

I did notice after taking it all out of the aircraft - still running - that there seemed to be a loss of wfi on the iPad for a second or so.. Perhaps this could just have been a poor connection somewhere.(?) and the cause of the data loss.
Anyway in case I have a faulty 801.11n dongle, I have ordered another. Strange though because it all worked normally in the car driving for about 30 mins with very good ADS-B reception and GPS position.
Tony