— Reader Terry points to this article in Aviation Week on preliminary findings that UWB interferes with airplane Instrument Landing Systems:
Ultrawideband transmitters temporarily “knocked out” the instrument landing system and traffic-alert collision avoidance systems during some very preliminary tests by NASA Langley.
The test was conducted with UWB transmitters inside the aircraft, where low signal levels are still sufficient to interfere. The Economist article below says this isn’t supposed to happen, but it does. UWB would be an ideal terrorist weapon in its current configuration, so it’s a no-go, except where locked-down.