Author Topic: Flightradar24 track error  (Read 2575 times)

frankmcm

Flightradar24 track error
« on: October 18, 2021, 11:04:53 pm »
My colleagues followed my recent crossing of the Irish Sea on Flightradar24, and hugely enjoyed my zigzag route line.  Some deviations are 20 miles from track.  My SkyDemon log, using PAW as navigation source, shows my actual and much straighter route.
I also have an accurate breadcrumb trail on my Garmin GDL795. I filed a flight plan and used a Basic service from appropriate controllers all the way across, and nothing to suggest that my routing was strange.
So am I really sending out inaccurate position data?   I have a Funke transponder connected to PAW.
I’m not sure if FR gets its data from ground radar, or if it uses my extended squatter.  In any case I would hate to broadcast data that falsely suggests I may be breaching controlled airspace, or might send a rescue helicopter to an erroneous last known position when I ditch.
Do I need to check something? Pointers would be appreciated.

Admin

Re: Flightradar24 track error
« Reply #1 on: October 18, 2021, 11:12:02 pm »
My guess would be that you are not in fact outputting an extended squitter
And the track you are seeing is a poor implementation of MLAT (multilateration)

Have you checked vector for your adsb performance?
Thx
Lee

frankmcm

Re: Flightradar24 track error
« Reply #2 on: October 19, 2021, 09:47:44 am »
Good thought.   I am grounded for a few days maintenance but will check this at earliest opportunity and report back. Thanks.

frankmcm

Re: Flightradar24 track error
« Reply #3 on: October 19, 2021, 01:21:00 pm »
So I have absolutely nothing on Vector, despite flying around Lancashire a few days ago. And I have plenty of traffic showing on screen.  More research required.

exfirepro

Re: Flightradar24 track error
« Reply #4 on: October 19, 2021, 06:07:26 pm »
Hi Frank,

Strange, as there are lots of active PAW ATOM-GRID Ground Stations in and around Lancashire. Unfortunately, Vector doesn't currently report Mode-S due to the extremely high levels of data storage and processing required to do so, however Vector should at least be reporting your PAW P3i transmissions - even if you aren't transmitting Extended Squitter ADS-B.

As Lee has commented, the most likely explanation for a 'jaggy' track on flight reporting websites is poor multilateration (triangulation of position) due to poor reception of Mode-S from your transponder to their Ground Receiving Stations (they certainly DON'T get reports from official Ground Radar!).

If you care to share some details - Aircraft Reg / ICAO, date and time of last flight and points of departure / arrival - I will take a look and try to work out what might be going on.

You can PM me via the details via the message board if you don't want to make the details public.

Best Regards
Peter

frankmcm

Re: Flightradar24 track error
« Reply #5 on: October 19, 2021, 06:43:28 pm »
Hi Peter
I flew EGAD to EGNF on Sat 16th, in an approximately straight line.
Out journey ~ 1100 hrs, returning ~ 1500 hrs.

G-CMON, RV7   ICAO 4075B1

I currently use the internal dipole aerials, but I have acquired a pair of external aerials still awaiting installation on the belly. PAW/SkyDemon sees plenty of traffic, so I had thought it was working.

I’m well capable of misconfiguring things, but at initial setup I believe it passed the post install check.  I will hunt out that report.

Regards
Frank


Ian Melville

Re: Flightradar24 track error
« Reply #6 on: October 19, 2021, 08:36:43 pm »
Frank, Can you show us screenshots of the home pages and status page of your PAW?

Admin

Re: Flightradar24 track error
« Reply #7 on: October 19, 2021, 09:26:38 pm »
+ Configure page

exfirepro

Re: Flightradar24 track error
« Reply #8 on: October 19, 2021, 11:11:30 pm »
Hi Frank,

Ditto to the above requests.

I take it you are based at (or near) Newtownards? PilotAware Ground Stations are unfortunately still very thin on the ground in N.I. (only 3 sites at Derry/Londonderry, Tandragee and Kilkeel), so I wouldn't necessarily expect great reports from the Newtownards area.

ATOM Ground Stations are, however, much more common over here on the UK mainland and as you flew from Newtownards direct to Netherthorpe on Sat 16th October, you will have passed a considerable number of them during that flight, yet I can find only one single report for 4075B1 in the PAW database, and that is a single P3i 'ping' at 66Km from PWShireN (near Chepstow) back on the 14th of May, with no record whatever either before or since, and no record whatever of any active ADS-B transmissions (which at much higher power would be more easily received at range). This clearly indicates to me that there is definitely something wrong with your equipment, setup or both.

This could be something as simple as that your PilotAware Licence has expired, but sight of the requested screenshots should help us identify the problem, or at least point us in the right direction as to the likely cause.

Best Regards Meantime
Peter

frankmcm

Re: Flightradar24 track error
« Reply #9 on: October 20, 2021, 01:59:49 pm »
Progress!   
My hex ID is wrong.   Currently set to FEDE60, which is the tail end of my SSID . 
Reset to correct hex, and seems to work .
Incidentally vector search on fede60 shows a reasonable polar diagram.  Moreover an “icao fede60” google doesn’t report another aircraft, so presumably the hardware is ok.
I have no idea when or how the hexID was changed. I have one software update and one iPad mini change in that time.  My setup test in June 2020 reports the correct hexID of 4075B1
Now to check if my Funke transponder has an issue. I seem to recall that it’s setup specifies a hexID. Should I be checking this ID regularly??? I would not have been aware of the issue had my colleagues not been following my route.

Thanks for the backup
Frank


exfirepro

Re: Flightradar24 track error
« Reply #10 on: October 20, 2021, 07:30:25 pm »
Hi Frank,

Thanks for the feedback.

That's one of the things we would have checked / seen from the requested screenshots. FEDE60 is obviously the 'default' Hex ID of your PAW, based on the last 6 digits of the unit's 'MAC' address - and allocated to the PAW automatically during pre-dispatch setup and testing. This, along with other 'default' settings is held in a default profile*, which is normally superseded when you create and save your own 'profile' during initial setup of your unit prior to your first flight. I have no way of checking your initial setup as there are as I say no reports on the database from 4075B1** and the earliest reports from FEDE60 start from 23 April 2021 and continue until 16 October 2021 from ground stations as far apart as Kilkeel, East Fortune and Edinburgh West, and the West and South West of England. The most likely explanation therefore in view of the lack of reports from 4075B1 is that the initial profile was set up and the post install check done, but that profile was either not saved or somehow inadvertently reverted back to the default at some time between the initial setup and 23 April 2021. Whilst historically we have had reports of units reverting to the default profile during updates or licence renewals, this was a bug which was sorted a long time ago, so this is unlikely to be relevant with the current software versions***. I am however aware of at least two recent cases where aircraft which I know personally have been operating on their correct ICAO Hex ID and have mysteriously reverted to the default, but I suspect that these were almost certainly finger-induced errors.

* Profiles are created to allow the unit to be 'swapped' between aircraft with minimal fuss and can be found from a button at the bottom of the PAW Configure Screen. They are created by re-configuring the unit to match each aircraft in which it is likely to be used, then 'Saving' each set of settings as an individual 'Profile'. The desired profile can then be be selected at will prior to flight in a different aircraft.

** With the exception of the single 'ping' from 4075B1 reported by PWShiren on 14th May, which is almost certainly a rogue transmission of some sort.

*** Unless of course you are still running old software - the latest released version is 20201101

Re your Funke Transponder - in view of the numerous recent reports on the database from your PAW transmissions, and the complete lack of reports for ADSB from either Hex ID, it is pretty certain that your transponder is NOT transmitting Mode-S/ES ADS-B, so this obviously needs further investigation. You can find several threads on this subject by searching 'Funke' from the Forum Home Page. Please feel free to come back to us for help if you need it.

Best Regards

Peter
« Last Edit: October 20, 2021, 07:34:06 pm by exfirepro »

frankmcm

Re: Flightradar24 track error
« Reply #11 on: October 21, 2021, 10:33:05 am »
I can’t work round the 512k file size for attachments, so limited images…Working on it, but iPhones have almost broken me…

I will sort the “save default profile “ issue now.

PAW Software versión 20201101.   Expiry 20211121

Will dig into the Funke configurations and report back.

Thanks again.

Frank







exfirepro

Re: Flightradar24 track error
« Reply #12 on: October 21, 2021, 08:34:22 pm »
Hi Frank,

I have sent you a PM via the message board.

Best Regards
Peter