The transition to iOS 11 was a smooth one for most pilots, but it wasn’t completely problem free. The update introduced a small bug affecting the iPad’s GPS when flying at high speeds. This would cause you to lose GPS location data on your iPad if you placed it in airplane mode and flew at a groundspeed over 300 knots, which would be a common scenario for jet operators.
After thoroughly testing the latest iOS 11.1 update, both ForeFlight and Bad Elf are reporting that the bug appears to have been fixed:
Compatibility testing between ForeFlight and iOS 11.1 is complete and we are issuing the “all-clear” to ForeFlight customers. Additionally, we believe that this update solves the issue involving GPS receivers used in high-speed aircraft that we found in previous versions of iOS 11.
Make sure to follow our iOS Update Green Light program for up-to-date guidance on when it’s ok to update to the latest iOS version.
Source: Ipad appsiOS 11.1 fixes high-speed GPS bug