http://en.wikipedia.org/wiki/Localizer_Performance_with_Vertical_guidance http://en.wikipedia.org/wiki/Localizer_Performance_with_Vert... GPS is also replacing

http://en.wikipedia.org/wiki/Localizer_Performance_with_Vertical_guidance http://en.wikipedia.org/wiki/Localizer_Performance_with_Vert... GPS is also replacing ground-based radar for traffic control in the US. It's a good idea to have alternatives in your cockpit, but 99% of the time GPS is the easiest and most accurate option.