BUG: Course navigation Climb Pro bug on a two directional part of course

I am reporting a bug that I observed during an ultramarathon race least weekend.

I had the entire 100 km race course loaded on the watch so that I could see all climbs and descents in Climb Pro and also use features like Up Ahead.

The race utilizes many parts of the race course twice with two directional traffic. The race course isn't completely out-and-back, but there are both loops and two-directional parts making the course more complex. There was one part where the actual race course slightly diverged from the planned one due to the last moment re-routing. That is probably important.

What I noticed after going through that rerouting for the second time is that the watch had a really hard time locking back to the course. Even though at that moment I was going back on course and climbing a long hill at around mile 32, the watch was repeatedly trying to lock me to around mile 6 of the course where I earlier went downhill on the same trail. So it repeatedly, for many times, went off course, then on course at the wrong part of course, then off course again, then on course again, and so on. That was driving me nuts. Needless to say that Climb Pro feature didn't work because it was showing me on the downhill instead of uphill. Up Head feature didn't work either.

How hard it is for the course navigation to use a best match based on my current distance to see where I am more likely to be on the course? Or perhaps it should use the direction of travel. Or perhaps the combination of the both factors. Anyway, that should be smarter than just blindly using the first possible position match on the course.

After a while the watch had somehow locked me to the uphill part of the course, but not before it caused a needless frustration.

I should add that the watch lost the course (went off course) multiple times when going through tight switchbacks in other parts of the race course. Garmin should realize that the course GPX files aren't always perfect so some tolerance for imperfect data should be allowed before triggering off-course alerts.

0 S4ndor over 2 years ago

Same error here. Yesterday my fenix made in the same way. I was forced to stop the course because it was so annoying , constantly on course/off course. Sometimes i was at the end of the course sometimes at he beginning on the climb pro. Couldn't stop the laerts neither..

Are chances that this bug will be fixed in the future?

0 HESHER over 2 years ago

I noticed this too and stopped course navigation

My takeaway is to not run races that have course overlap :)

0 S4ndor over 2 years ago in reply to HESHER

Or maybe I should let the watch at home and follow the others on the course :))

0 silentvoyager over 2 years ago in reply to S4ndor

Yes, the issue is still there, as well as a number of other navigation issues. I've had this exact issue two days ago when running a 50K trail race. There was one part of the race course with two way traffic. The course tracking got off at one point, which is a separate issue, then it locked to the initial part of the course that I ran earlier. Then it couldn't get it right for a few minutes. The ClimbPro was obviously wrong too, as well as the elevation profile.

And the reason the watch goes of course so easily is also a well understood issue that Garmin knows about. The algorithm for tracking a course is deficient. It doesn't handle a case when the course makes a sharp turn. You can try it for yourself - make a course that makes a 180 degree turn. I'll guarantee that if you try to follow that course your watch would go off course when approaching the turn. I seems that the algorithm expects to keep moving towards a point on a course that is slightly ahead (e.g. about 15-30 meters or 50-100 feet). However, if there is a sharp turn, that point that is tracking ahead of the current position may end up being behind you. It is ahead on the course as the course goes, but because of the sharp turn but you may end up moving away from it. The watch interprets that as going off course. Similarly, if you stop on a course for whatever reason or if the moving speed is very slow, the GPS positions may wobble a bit and a new GPS position may end up dropping slightly behind the current position, away from the next point on course. The watch navigation interprets that as going off course too, and it seems to be overly sensitive.

Once it is off course it can lock to another part of the course that happens to be at the same position. As a variant of the above issue, sometimes on the way up to a mountain the watch may lock to a return path from the same mountain. If that happens, the elevation profile gets completely screwed - it basically cuts the entire top of the climb and stops reacting to any changes in altitude until you hit the same spot on the way back.

Someone at Garmin needs to look at all of these issues in a systemic way, but it has been this way for at least the last 3 years, and I don't think that anything would ever be changed. Too few people complain to Garmin about these issues, and Garmin doesn't seem to care to make these things right even though they are obviously broken.