ADS-B aircraft now only reported as MLAT?

[hansp]

Hi! Any idea why an aircraft (SE-VPF) with ADSB-out, that before has been perfectly tracked and displayed as ADSB, now shows up - very poorly - as MLAT? And simultaneously is tracked on f.ex. FA and ADSBX with 100% coverage, as ADS-B?

[user12345]

Hi! Any idea why an aircraft (SE-VPF) with ADSB-out, that before has been perfectly tracked and displayed as ADSB, now shows up - very poorly - as MLAT? And simultaneously is tracked on f.ex. FA and ADSBX with 100% coverage, as ADS-B?

Feeders in your area have disconnected their service, is the most likely explanation.

[hansp]

I don´t buy that. 2 of my 4 feeders in the region are temporarily out of service, the other 2 are updated and configured correctly. And on the airfield there is a F-feeder up and running. And also other services report the aircraft correctly. If there is some setting that needs to be changed in the FR24feed-settings I´d like to know. None are using MLAT as FR24 requests since they also feed other services.

[user12345]

I don´t buy that. 2 of my 4 feeders in the region are temporarily out of service, the other 2 are updated and configured correctly. And on the airfield there is a F-feeder up and running. And also other services report the aircraft correctly. If there is some setting that needs to be changed in the FR24feed-settings I´d like to know. None are using MLAT as FR24 requests since they also feed other services.

support@fr24.com

[hansp]

support@fr24.com

We did and got a nonsense reply about coverage in the area, filtering on the website etc. The issue is still the same as in the first post. There is nothing wrong with the data sent to FR24, there is something wrong with how this particular aircraft is handled.

[user12345]

We did and got a nonsense reply about coverage in the area, filtering on the website etc. The issue is still the same as in the first post. There is nothing wrong with the data sent to FR24, there is something wrong with how this particular aircraft is handled.

If you read the old threads you'll see there were a lot of disgruntled feeders after FRs decision to terminate MLAT feeds. Rather than disable MLAT which would impact all the other tracking sites they also feed to, many chose to simply remove the feed to FR and contined to feed MLAT to the other tracking sites. I have just checked the plane in question on other tracking sites and it is showing perfectly there with no gaps in its flight paths around the Kristianstad airstrip so it appears to be a 'lack of feeders' issue.

If you delve even deeper into the old messages you'll see that FR has some quirky ways of displaying the data from the feeder sites too. Before they removed the feeder ID tags you could see whose feed was showing each plane on the map. Some feeders reported having their receiver right next to the airfield with clear unimpeded views for 200 miles in every direction, but FR would be showing the planes from a receiver 50 miles away in the bottom of a valley, meaning that planes on final approach would stop tracking in mid-air at 2000 ft. There seems to be some sort of internal feeder rank list for each area, and so it doesn't matter if your receiver is situated at the airfield, it will choose to display data from the receivers with the higher rankings.

I believe Oblivian has better insights into this so may be able to chime in with his thoughts, but I doubt you'll ever see any change here.

[hansp]

Thanks for replying to this in length. However, it is still an ADS-B aircraft so MLAT coverage does not apply. Have a look at a similar aircraft landing at the same airport on the same time VPF was active, also with ADS-B (https://www.flightradar24.com/data/a...e-vuz#330ee1f4) and how it is reported. I find no technical reason why VPF should not be displayed in the same way unless there is a reason for FR24 to filter it out but I guess I´ll never find out.

[Svedan]

I have the same issue as Hansp. FR24 filters out ADS-B on our particular aircraft.

Since 2-3 months ago our ADS-B aircraft (SE-XTF) has started showing up as M-LAT on FR24.

Other ADS-B equipped aircraft flying in the same area at the same time show up as ADS-B on FR24
Our aircraft shows 100% ADS-B coverage on other tracking sites like adsbexchange

Here is an example from today 11:13 UTC comparing FR24 with ADSBexchange.

FR24: SE-XTF shows as MLAT while surrounding aircraft in the same area and altitude shows as ADS-B
FR24.png


ADSBexchange: All aircraft including SE-XTF shows as ADS-B
ADSBex.png

[hansp]

I see that it is also discussed on EuroGA here. So the problem seems to be not only Sweden. I have basically given up since support does not be able - or have interest - to support on issues that might be feeder-related. I guess the money is in the big planes for passengers to be able to see if their flight from major airports are delayed. A shame really. To be honest both FA and RB have far better representation of small aircraft if you want a fancy graphical interface. I still have an outstanding problem with my own aircraft specifically on both those services but that's another story.

[JBAviation]

I have the same issue as Hansp. FR24 filters out ADS-B on our particular aircraft.

Since 2-3 months ago our ADS-B aircraft (SE-XTF) has started showing up as M-LAT on FR24.

Other ADS-B equipped aircraft flying in the same area at the same time show up as ADS-B on FR24
Our aircraft shows 100% ADS-B coverage on other tracking sites like adsbexchange

Here is an example from today 11:13 UTC comparing FR24 with ADSBexchange.

FR24: SE-XTF shows as MLAT while surrounding aircraft in the same area and altitude shows as ADS-B
FR24.png


ADSBexchange: All aircraft including SE-XTF shows as ADS-B
ADSBex.png

This is exactly what is happening with an aircraft from my local flying school (23-1560) up until November 5th 2023, it was being tracked perfectly by Ads-b, after that date it has been tracked poorly or not even tracked at all by MLAT, obviously the coverage of MLAT in my area isn't good hence why it isn't showing up, but the Ads-B coverage is fine because all the other planes from my flying school show up and track just fine with source being Ads-b, so something on November 5th in Flight radars system made it change to MLAT only on that aircraft.https://www.flightradar24.com/data/aircraft/23-1560# also for the same aircraft on Flight aware and Ads-b exchange the source is Ads-b so it's definitely a Flight radar problem.

[Svedan]

This is exactly what is happening with an aircraft from my local flying school (23-1560) up until November 5th 2023, it was being tracked perfectly by Ads-b, after that date it has been tracked poorly or not even tracked at all by MLAT, obviously the coverage of MLAT in my area isn't good hence why it isn't showing up, but the Ads-B coverage is fine because all the other planes from my flying school show up and track just fine with source being Ads-b, so something on November 5th in Flight radars system made it change to MLAT only on that aircraft.https://www.flightradar24.com/data/aircraft/23-1560# also for the same aircraft on Flight aware and Ads-b exchange the source is Ads-b so it's definitely a Flight radar problem.

For me, it was working fine on November 26th, but on the next day, it was showing as M-LAT, and has done so since then.

The only thing I could think of was that after the flight on the 26th, I updated the software in my Garmin G3X to version 9.31.

What kind of equipment do you have in your aircraft?

[JBAviation]

For me, it was working fine on November 26th, but on the next day, it was showing as M-LAT, and has done so since then.

The only thing I could think of was that after the flight on the 26th, I updated the software in my Garmin G3X to version 9.31.

What kind of equipment do you have in your aircraft?

very interesting the aircraft has the same a Garmin G3X system so maybe my flying school may have updated the software on that day and something may have happened, it just doesn't explain to me why it is only happening on flight radar.. Also I was just looking at the playback of a flight you did yesterday and the data source says Ads-b and as from May 16th, did you update your Garmin to a newer version? or did Flight radar somehow magically fix it?

[Svedan]

very interesting the aircraft has the same a Garmin G3X system so maybe my flying school may have updated the software on that day and something may have happened, it just doesn't explain to me why it is only happening on flight radar.. Also I was just looking at the playback of a flight you did yesterday and the data source says Ads-b and as from May 16th, did you update your Garmin to a newer version? or did Flight radar somehow magically fix it?

I had not noticed that we were getting picked up as ADS-B again in FR24. I have not updated my Garmin software.

Looking at the flight on May 18th, on the way out it was still showing M-LAT but after I landed and on the way home it was ADS-B. However, the other aircraft flying in formation with me (SE-VOK) was showing up as ADS-B both on the way there and also on the way home. The same thing also happened on the May 16th

Could this be dependent on which FR24 receiver first picks up the aircraft ADS-B transmission?

Could there also be a technical reason behind this? For example, my aircraft has the GPS antenna connected directly to the Garmin Display Unit, which does not have a certified GPS receiver so technically I’m not ADS-B compliant and therefore my ADS-B transmission will have the worst integrity/accuracy parameters. Maybe this gets filtered out by some FR24 receivers?

Could Garmin version 9.31 possibly have changed the way G3X transmits ADS-B signals when it senses it's not connected to a certified GPS receiver (e.g. GPS 20A or GTN 650)?

Checking ADSBexchange I can see that I have the following ADS-B accuracy/integrity parameters:

NACP: EPU < 10 m
SIL:> 1e-3 per flight hour (I guess this corresponds to SIL = 0)
NACV: < 3 m/s
NICBARO: cross-checked
RC: unknown

Looking at flights before I installed version 9.31 will show the same accuracy/integrity data, however, there might be more parameters being transmitted than those seen on ADSBexchange.

[JBAviation]

I had not noticed that we were getting picked up as ADS-B again in FR24. I have not updated my Garmin software.

Looking at the flight on May 18th, on the way out it was still showing M-LAT but after I landed and on the way home it was ADS-B. However, the other aircraft flying in formation with me (SE-VOK) was showing up as ADS-B both on the way there and also on the way home. The same thing also happened on the May 16th

Could this be dependent on which FR24 receiver first picks up the aircraft ADS-B transmission?

Could there also be a technical reason behind this? For example, my aircraft has the GPS antenna connected directly to the Garmin Display Unit, which does not have a certified GPS receiver so technically I’m not ADS-B compliant and therefore my ADS-B transmission will have the worst integrity/accuracy parameters. Maybe this gets filtered out by some FR24 receivers?

Could Garmin version 9.31 possibly have changed the way G3X transmits ADS-B signals when it senses it's not connected to a certified GPS receiver (e.g. GPS 20A or GTN 650)?

Checking ADSBexchange I can see that I have the following ADS-B accuracy/integrity parameters:

NACP: EPU < 10 m
SIL:> 1e-3 per flight hour (I guess this corresponds to SIL = 0)
NACV: < 3 m/s
NICBARO: cross-checked
RC: unknown

Looking at flights before I installed version 9.31 will show the same accuracy/integrity data, however, there might be more parameters being transmitted than those seen on ADSBexchange.

That's interesting who knows what it could be, but I have a feeling it has to do with that Garmin version like you said where it may have changed the way Ads-b is transmitted and maybe Flightradar is getting confused by it.

[hansp]

That's interesting who knows what it could be, but I have a feeling it has to do with that Garmin version like you said where it may have changed the way Ads-b is transmitted and maybe Flightradar is getting confused by it.

No no no please. We´ve been down that road, chasing software version of our equipment etc. Not showing on FR24 but showing up on ADSBX or RB or FA etc - then the cause "is not me - it´s you" (you being FR24)

The values by Svedan are excellent. And funny enough today one of our "troubled" machines showed up fine on FR24... someone maybe finally listened.