The USA proposes to retain ground-based navigation aids because of the vulnerability of the global positioning system (Flight International, 18-24 June).
I am puzzled. Surely a satellite-based system can only be interfered with by the broadcasting of misleading signals on the system's frequency. Presumably the person thus interfering could equally broadcast misleading signals simultaneously on one or more frequencies associated with the ground-based back-up, or physically destroy it, rendering the back-up system useless.
Am I missing something?
Michael Stannard
Ewell, UK
Editor's note: a single transmitter can jam GPS in a wide area, whereas each ground beacon has a different frequency, so it is less easy to jam a whole region.
Source: Flight International