found online by Raymond
From Our favorite Earth-Bound Misfit:
One of the side-effects of a war between adversaries with first-world comparable EW gear will be a loss of the GPS network. Whether it will be world-wide or localized to the combat area(s), whether the GPS constellation itself will be disrupted is a matter of speculation.
But what will also likely happen is a disruption of the global air traffic system. The short-sighted beancountrs in the FAA have been pushing the decommissioning of a large chunk of the VOR network and shutting down VOR/DME -based approaches.