wrote in message
oups.com...

The controller's attention might be elsewhere (have you never been sent
right through a localizer?).


There's no similarity. There's a window of a few seconds for the turn to
intercept the localizer. It would take at least several minutes for the
controller to notice an enroute aircraft drifting off course unless the GPS
was erroneously calling for a significant turn. If it did that the pilot
should notice the error before the controller.