The Malaysian airliner crash in eastern Ukraine on Thursday came on the 18th anniversary of another huge aviation disaster. TWA Flight 800 exploded midair and crashed into the Atlantic Ocean off Long Island on July 17, 1996, killing all 230 people on board. Investigators determined the likely cause was a spark igniting vapors in a fuel tank, but many conspiracy theories about the disaster have persisted, including claims that it was brought down by a missile.
