GPS is incredibly flimsy. Normally it operates by taking the average of 1000 observations to generate a noisy signal. It's not that difficult to be louder than something shouting from space. You can pick up cheap GPS blockers easily about the size of a walkie-talkie (handheld radio).
> By carrying a group of atoms cooled to -273C on the plane itself, rather than relying on an external signal, the technology can't be interfered with by jamming.
Last year I was on a plane where if the engines were not running, it entirely went into darkness. They hooked the plane up to the airport and tripped the airport electrics too. Now imagine if your plane loses power momentarily, and suddenly your GPS stops working entirely.
> Henry White, part of the team from BAE Systems that worked on the test flight, told BBC News that he thought the first application could be aboard ships, "where there's a bit more space".
> Quantum clocks, gyroscopes and accelerometers are large, bulky and incredibly expensive, with an accurate quantum clock costing around £100,000. Yet military research is allowing the creation of smaller, better and cheaper systems.
Likely a minimum of 10 years from being viable. Mt White of BAE is politely saying as much.