Hi everyone, I’m encountering a strange issue with GPS tracking in my app, and I’m hoping for some insights. I’m developing an app that records users' GPS activities (walking, biking, etc.) with app in the foreground and/or background. Most activities are outdoors, sometimes in areas with poor GPS reception, such as mountains. To track user location, we’re using: locationManager = CLLocationManager() locationManager.distanceFilter = 3 locationManager.activityType = .fitness locationManager.pausesLocationUpdatesAutomatically = false locationManager.allowsBackgroundLocationUpdates = true The Issue In certain scenarios, the GPS behaves unexpectedly. For example (see attached image below): A user followed a normal route (brown line), then reached an intersection and turned right (blue arrow). However, the GPS continued straight for about 200 meters (brown line) before correcting itself and resuming accurate tracking. Here’s a snippet of the recorded coordinates during this misbehavior: time,latitude,longitude,elevation,verticalAccuracy,horizontalAccuracy 10:17:17,47.92408,7.10438,950.82375,4.74865,4.80005 10:17:33,47.92410,7.10435,950.14966,4.74865,4.10799 10:17:44,47.92412,7.10431,943.63913,4.74865,4.46287 10:17:53,47.92413,7.10427,939.51380,4.74865,4.60644 10:17:59,47.92415,7.10424,934.82986,4.74865,4.52599 10:18:02,47.92417,7.10420,932.53145,4.74865,4.823035 10:18:05,47.92418,7.10416,927.84917,4.748655,4.59619 10:18:09,47.92420,7.10413,924.89886,4.748655,4.50172 10:18:13,47.92422,7.10409,923.35354,4.74865,4.77356 10:18:18,47.92424,7.104055,920.16327,4.74865,4.78286 10:18:22,47.92426,7.10400,915.23174,4.74865,4.66226 10:18:28,47.92427,7.10397,906.08626,4.74865,4.97331 10:18:31,47.92429,7.10394,903.25157,4.74865,4.81649 10:18:35,47.92431,7.10390,895.27948,4.74865,5.15392 10:18:38,47.92433,7.10386,889.71076,4.74865,5.25283 10:18:42,47.92435,7.10382,881.74041,4.74865,5.49089 10:18:46,47.92437,7.103785,874.34945,4.74865,5.55564 10:18:49,47.92439,7.10374,869.63184,4.74865,5.37537 10:18:53,47.92441,7.10370,861.26690,4.74865,5.39344 10:18:57,47.92443,7.10366,854.67646,4.74865,5.30404 10:19:01,47.92445,7.10362,848.48881,4.74865,5.59742 10:19:06,47.92447,7.10359,836.48915,4.74865,5.65666 10:19:08,47.92449,7.103555,835.72566,4.74865,5.54957 10:19:10,47.92450,7.10352,834.41579,4.74865,5.63540 10:19:13,47.92452,7.10348,830.17080,4.74865,5.65795 10:19:16,47.92454,7.10344,828.17052,4.74865,5.72169 10:19:19,47.92456,7.10340,824.93658,4.74865,5.62606 10:19:24,47.92458,7.10337,818.40503,4.74865,5.23265 10:19:34,47.92460,7.103335,804.42539,4.74865,4.683855 10:19:38,47.92462,7.10329,799.51747,4.74865,4.47590 10:19:48,47.92464,7.10324,784.97044,4.74865,4.59459 10:19:50,47.92466,7.10320,782.04750,4.748655,4.71036 10:19:57,47.92468,7.10317,777.49314,4.74865,4.60504 10:20:05,47.92469,7.10313,771.30168,4.74865,4.35574 10:20:09,47.92472,7.10308,766.64446,4.74865,4.94510 10:20:13,47.92474,7.10304,757.33384,4.74865,5.39175 10:20:15,47.92476,7.10300,753.52157,4.74865,5.442045 10:20:20,47.92477,7.10297,742.66179,4.74865,5.52391 10:20:23,47.92479,7.10293,735.38369,4.74865,5.44657 10:20:25,47.92480,7.10290,732.19367,4.74865,5.519945 10:20:28,47.92482,7.10286,725.15380,4.748655,5.58173 10:20:31,47.92484,7.10282,717.08813,4.74865,5.37805 10:20:34,47.92486,7.102785,710.35208,4.74865,5.27918 10:20:37,47.92488,7.10274,706.16774,4.748655,5.53270 10:20:40,47.92490,7.10270,702.84802,4.74865,5.71088 10:20:41,47.92648,7.10356,940.27115,6.600805,10.78768 10:20:43,47.92651,7.10355,940.24665,6.61807,10.45243 At 10:17:44, the location data was correct. Shortly after, CLLocationManager started returning inaccurate coordinates. Despite the system reporting good horizontal and vertical accuracy, the altitude readings drop progressively from 940m to 702m, even though the user remained at 940m in reality. (We also recorded barometric elevation, which confirms that he stayed around 900m) Then, at 10:20:41, the GPS corrected itself. Questions Is it possible that GPS could "lock onto" the wrong path, generating valid-looking but incorrect coordinates? Can we force CLLocationManager to use GPS exclusively (disabling other sensors like Wi-Fi)? I assumed that setting activityType = .fitness would prioritize outdoor tracking, but I’m still being located indoors. Could adjusting the activityType improve this behavior? Could having multiple CLLocationManager() instances in our app cause issues? (We use one to save the GPS coordinates, but MapBox also creates a CLLocationManager with lower accuracy for its Telemetry framework, for example) Thanks in advance for any help or suggestions!