GPS recorded wrong track not according to the map or reality

Last Saturday I run a half marathon and in the middle of the race I got a completely strange GPS recording tracking going by far of the supposed to be correct race track...

Time counting was ok, suddenly the recording jumped from 11 to 12 km and it messed up all my data... Distance became longer and pace became faster than the reality.

Is there a way to fix the GPS data manually? And How can this kind of problem be avoided?

Thanks for the support.

/Fabio

What it should be: race offical track

What is actually recorded: <iframe src='https://connect.garmin.com/modern/activity/embed/8865411313' title='Gothenburg Corrida' width='465' height='500' frameborder='0'></iframe>

0 trux over 2 years ago

Evergreen said:
Is there a way to fix the GPS data manually?

You can correct the distance manually by editing the activity. However, as for the map track, you'd need to export the file, edit in an external tool, and then import back (after deleting the original). Easier done with the TCX file format, but there are also editing tools able to work with Garmin's native FIT file format. For example plotaroute.com can handle FIT files. On my mind it is not worth of the effort. In your place, I'd just edit the total distance (using the official map), and write into the notes there was a GPS error, for later reference.

Evergreen said:
And How can this kind of problem be avoided?

Keeping as far as possible from buildings, walls, and other obstacles (although, looking at the map, it does not really seem to be the problem in this case). Updating the ephemeris file over Garmin Express shortly before the activity (especially if it is an important one). Updates over the Garmin Connect Mobile tend to fail easily. Turning on the option GPS+Galileo in the concerned activity settings. Verifying you have the last available firmware version. Rebooting or soft-resetting the watch up and then, to clear up potential cumulation of dead memory allocations.