THERE is a particularly treacherous type of accident which occasionally destroys aircraft that are working faultlessly. It is called "controlled flight into terrain", and it occurs when some sort of human error on the aircraft or on the ground causes it to fly into the dirt.
Last September an accident like this occurred on Mars. Space workers at NASA's Jet Propulsion Laboratory in Pasadena sent routine navigational commands to the Mars Climate Orbiter as it approached the red planet. But due to a series of human errors, the commands turned out to be wrong and the probe dipped low into the atmosphere instead of entering orbit. The spacecraft probably blew up, burned up or buried itself in the Martian soil; either way NASA never heard from it again. It was a classic "controlled flight into terrain" accident, but this time on another planet.
Only a few weeks later, in early ...
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