Investigators don't yet know why the tail fin and rudder broke off in flight just before American Airlines 587 crashed, but such a catastrophic loss has occurred just once before in commercial aviation history.
On Aug. 12, 1985, a Japan Air Lines jumbo jet lost its vertical tail section on a flight from Tokyo to Osaka. The Boeing 747 flew in circles for half an hour before crashing into a 7,000-foot mountain, its pilots still trying desperately to understand why they had lost control.
That crash killed 520 people, the worst single-aircraft mishap in commercial aviation. Four people survived.
In the 1985 crash, the aircraft suffered "massive decompression" _ a sudden loss of cabin pressure _ when the dome-shaped pressure seal in the rear of the passenger compartment unexpectedly collapsed.
The explosive force destroyed the aircraft's hydraulic lines that converged in the tail, and ripped away the vertical stabilizer and rudder.
Unable to see the plane's rear, the cockpit crew did not know it had lost the tail, only that the aircraft's control surfaces _ flaps, elevators and rudder _ were suddenly and mysteriously inoperative.
Capt. Masami Takahama told air controllers that a rear door had broken, declared an emergency and was cleared to land at either of two nearby airports.
Takahama was able to steer the plane by applying and easing power to the engines, but with no rudder to control the turns, the jetliner turned in circles, unable to set a course for either runway.
Photographs taken by witnesses on the ground clearly showed the plane's tail fin was missing.
Investigators eventually found that the plane's rear pressure dome, damaged earlier in a "hard landing," had been improperly repaired, and eventually gave way during the Tokyo-Osaka flight. Boeing, which had supervised the pressure dome repairs, took responsibility for the failed repairs.