Flarm traffic is shown in safesky as Mode S

English
1

Aircraft with Flarm shows as Flarm at takeoff but after a few seconds shows as Mode S on safesky. On Glidertracking sites the aircraft is visible as Flarmtraffic the whole time.

2

I observe the same. Glider tracking sites show more flarm targets than SafeSky.

3

Maybe SafeSky isn’t taking data from the glider tracking network?
Or perhaps the connection, if there was one has stopped working…

4

Hello @ms172,

SafeSky aggregates traffic from multiple sources and ground stations, always prioritising the most up-to-date traffic information.

In your example, could it be that the aircraft is equipped with both FLARM and a Mode-S transponder? If so, it might be detected more quickly when close to the ground via FLARM, and then multilaterated at altitude once it’s within range of enough ground stations for MLAT. Do you have the hex code for this aircraft so we can verify?

That said, if the assumption below is correct, FLARM traffic is likely to be more accurate than Mode-S, as FLARM positions come directly from GPS. In this case, we should adjust the priority and, when both FLARM and Mode-S are available, prioritise FLARM by default.

Thanks for spotting this, we’ll review our logic on this as well.

Fly safe,

Tristan

5

Hello Tristan,

yes, Aircraft is equipped with both Flame and Mode S. Hexcode should be 3D1049

Has the priority (Flarm vs Mode S) recently changed, because a year ago or so I if I remember correctly Flarm was shown on this aircraft and not Mode S.

Regards

Matthias

6

Thanks @ms172 , we have then found the explanation :slight_smile:

The logic itself hasn’t changed recently, but the expansion of ground stations has. You’re likely now within optical range of a newer station, which is triggering the multi-alteration of your Mode-S.

That said, we are already adapting our logic to prioritise FLARM when available, as this makes more sense.

Fly Safe,

Tristan