The circumstances were chillingly similar. Last Aug. 31 a small private plane took off from a suburban Los Angeles airfield, flew into the restricted airspace that protects Los Angeles International Airport without informing controllers, and collided with an Aeromexico jetliner. Eighty-two people died. Last week a single-engine Mooney aircraft lifted off from a municipal airfield 15 miles south of Salt Lake City, intruded without warning into the restricted zone around the city's international airport, and struck a SkyWest commuter airliner. All ten people in the two planes were killed.
In each case visibility was excellent. In each, the pilots of the...