Dangerously dependent on a whole lot of systems. Never mind the GPS unit in the police car/ambulance whatever, the radio systems now in use by the emergency services rely on the mobile phone network, their vehicles rely on oil, their control rooms rely on electricity, the list of technologies that are relied upon is endless, GPS is kind of low on the list.
Want to confine to to say aircraft? well then TCAS is just as easy to disrupt, and even worse, different parts of the world rely on that ssytem in different ways, so it is already a great potential danger, some nations teach pilots to obey TCAS over air traffic control, where others teach the other way round.
Yet more slow news day scaremongering.