A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Bob Goethe
Date: 2016 Nov 1, 13:37 -0700
The Royal Majesty cruise ship had the cable to their GPS antenna come loose, and the GPS defaulted back to a DR mode...and none of the bridge crew noticed that the GPS display was showing a "DR" indicator, and they ended up 14 miles off course and ran aground.
The error here was not with the GPS itself, but with the failure of the crew to read the GPS display carefully ...and to use no independent methods (LORAN, RADAR, celestial) to check their position. Had they used some other method, it would have shown up a discrepancy that would have triggered a closer look at their GPS data.