It was likely a grid navigation error - probably a case of adding instead of subtracting (or vice versa). I doubt that the aircraft has GPS. The 737-200 is hardly modern. Grid Navigation is used when flying close to the poles. Rankin Inlet may seem far north, but its not nearly far enough to be using Grid.
Yes the A/C had a retrofitted GPS.
And the a/c came from NWT air, not Air North...
