Investigators are looking at a little-known phenomenon known as wind rotors for clues to why a jetliner went into a nosedive and crashed, killing all 25 people on board.

Wind rotors occur when winds curl under and form undercurrents flowing in the opposite direction.The theory has come up in the investigation of the March 3 crash of United Airlines Flight 585. The plane's landing approach was normal until its last six seconds, when it pitched out of control and buried itself more than 15 feet in the ground.

Investigators believe that neither the pilot nor the co-pilot had suffered an incapacitating injury; there was plenty of fuel; there is no sign of sabotage or a major collision with a bird, and the engines were running normally.