Leaps in unmanned aircraft technology have military authorities clamoring to use more drones for everything from coastal patrols and border surveillance to tracking natural disasters. However, fears of midair collisions are slowing any broad expansion of their domestic use. FAA officials made it clear in a recent closed government conference that until the pilotless aircraft gain the high-tech ability to sense and avoid commercial aircraft and other airborne objects, the government is unlikely to allow them to operate much more freely in congested airspace.
