Month: March 2009

My wife sent me this excellent article about an airplane crash that happened over Brazilian airspace half a decade ago.  This particular crash is interesting, in that it is one of the few mid-air collisions between two aircraft – an exceedingly rare occurrence, as most crashes occur on takeoff or landing.  In this particular case, a small executive jet sheared off the wing of a Boeing passenger jet at 37000 feet.

The article is interesting, in that it discusses a couple of failures of industrial design.  Of particular note, virtually all planes have an on-board computer that is designed to prevent in-air collisions.  But it only works if the plane’s transponder is on.  In this case, the pilots of the smaller jet accidentally turned their transponders off.  Unfortunately, the collision computer didn’t have an angry blinking error message, and instead had the benign error code “Standby”.  The two pilots had never flown the jet before, and as such didn’t notice that something was wrong.

Another interesting part of the article discussed how navigation computers have perversely made things less safe.  When humans fly planes, there’s a lot of wiggle room in the exact paths they end up on – there’s no guaruntee that a pilot will follow his exact planned flight path, or go to his exact prescribed elevation.  But when computers are choosing the flight path and driving the plane, it creates actually increased chance that two planes will be put on exactly the same trajectory.