Aircraft Flying Backwards

[SGS66]

I have a track log which when played on Aircrew has an aircraft flying backwards on final. If anybody wants to debug the file I will send it via email. As it happens I know the aircraft concerned and checked. The pilots were using SE2 and they were navigating their flight with SkyDemon using SE2 to give them the GPS data and traffic and that all was fine as far as they were concerned.

They assure me they were not flying backwards on final. Actually after landing on 'roll out' their aircraft was going forward.

This is not the only time I have seen this phenomena.

The pilots also said that their SE had tracked my aircraft which has a Garmin 330 ES mode S transponder ie with ADS-B out.

[Admin]

Hi SGS66

unfortunately the track log is after decoding, and this is an error before decoding.

The track is determined by the ADS-B reported velocity E/W and N/S
https://mode-s.org/decode/adsb/airborne-velocity.html

At the heart of the ADSB decode is dump1090, this is used by every ADSB decoder in the world!
so if the track is incorrect, it is the ADSB transmission

You say flying backwards, are you sure it was not NORTH up ?
This would indicate no velocity component for E/W or N/S

Thx
Lee

[AlanG]

Lee

I have never seen this happen in my EFB in flight but do often see a/c apparently flying backwards when monitoring my OGN-R via VRS and I think I have seen it when simultaneously monitoring my EFB connected to my static PAW but assumed it may be due to it being static.

Regards
Alan

[Admin]

Lee

I have never seen this happen in my EFB in flight but do often see a/c apparently flying backwards when monitoring my OGN-R via VRS and I think I have seen it when simultaneously monitoring my EFB connected to my static PAW but assumed it may be due to it being static.

Regards
Alan

I think there are a number of issues with transponders getting this wrong.

I think there are 2 buggy versions of Funke transponder firmware
one release has planes always pointing North
the other release has the planes pointing backwards

Thx
Lee

[Ian Melville]

I had an RV overtake me, going backwards E-W. I think he had a Funke Transponder.

[JCurtis]

At the heart of the ADSB decode is dump1090, this is used by every ADSB decoder in the world!
so if the track is incorrect, it is the ADSB transmission

Not if you use an RF front end and throw the data into an FPGA to do to decode, rather than an SDR dongle....

[SGS66]

Lee, thanks for looking at this. Using the Aircrew playback the false heading of this aircraft does appear to be a Northerly direction but I am not familiar with decoding the numbers hence my original suggestion. This aircraft also appears to have several seconds between transmissions - how often do these SE devices transmit ?

I checked the other instance I have of an aircraft flying backwards and that was heading backwards in an exactly northerly direction (Aircrew playback). The a/c was also indicating the presence of ADS-B according to Aircrew playback.

Two different aircraft both saying they have ADS-B out and giving duff information as regards heading - not sure what can be done about this but I guarantee it is not limited to two aircraft.

Thanks for the explanation of the track info available to us for download ie that it is processed data.

[Admin]

Hi SGS66

Unfortunately there is nothing we (PilotAware) can do, the fault is at the transmitting end not the receiving end I'm afraid.

Thx
Lee

[SGS66]

I understand, but on the question of how often SE transmits ?

[Admin]

I understand, but on the question of how often SE transmits ?

I think it’s approximately 1/second, but not really a question we can answer

If you are seeing several seconds between each packet, I am guessing it is down to obscuration
We have been monitoring the performance of these low power CAP1391, and their range appears severely limited when used in a metal aircraft in the cabin

Thx
Lee

[CliveJ]

Does anyone have any more information for why this happens?

My hangar mate's plan is always 'North Up' for me on my PAW though if I look at him on any of the radar apps he's pointing the way he's going. As he's invested in his SE he just shrugs when I tell him.

Is there something that can be done to the SE, or is it something that should be directed to the SE community?

It's not a big deal but it maybe allied to the fact he does disappear now and again. Yesterday for much of the time he wasn't showing as ADSB, just as a TXP bearingless target, his relative height looked right. Then while he was in the circuit he showed up, North up tho.
Regards, Clive

[steveu]

Is the firmware in his SE up to date? Is your PAW firmware up to date?

Has he got a transponder?

If his SE hasn't got GPS location it will not transmit...

If you mate is happy with SE then maybe best leave him be...

[Admin]

are you sure this is an SE ?
We used to see this on an old revision of the Funke firmware

Can you share the ICAO code / tail reg of the offending device please

Range of SE is pretty poor, that will be why he drops off.
With the ICAO we could look at his vector transmission pattern.

The fact that he appears track up on flight tracking apps, I think they are determining his track by successive position reports.
If his track is not being reported, it may be because his GPS is not reporting speed, which would generally mean that the track field would be ignored

Thx
Lee

[CliveJ]

Hi Lee, yes I remember the Funke. I had one.

Yes it's a SE though I will check the configuration and have a more in depth chat with the pilot.

The HEX is 4073E4. G-FOKS

I can't get the Vector to work ATM. Tried on two browsers and 2 PC's and a phone, is it only me?

Thanks Clive