iOS 11 tracking inaccurate when running, accurate when cycling

Number:rdar://646839378473 Date Originated:
Status:Open Resolved:
Product:iOS Product Version:11.0+
Classification: Reproducible:Yes
I use an Apple iPhone 7 and Endomondo to track my runs and when cycling. Since updating to iOS 11 in Sep 2017 the tracks for my runs are extremely incorrect. At the same time, other activities like cycling and driving have nearly perfect tracks.

Steps to Reproduce:
This issue occurs whenever I run and track my workout with various apps. Tested with Endomondo, RunKeeper, Strava. If I cycle, the tracks are almost perfect.

Tested in various locations over a 6-month period. None of the updates for iOS fixed the issue.

Expected Results:
Running tracks should be as accurate as cycling tracks.

Actual Results:
Running tracks are inaccurate, skipping turns and having huge jumps in the data.
iOS 11.3

Apple iPhone 7, plastic case. The same case was used prior to iOS 11. The runs are usually in an open park without any nearby buildings or other obstructions.



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