KUALA LUMPUR: Investigating authorities engaged in the search for the missing Malaysian Airlines Flight MH370 are on the verge of dismissing the theory that pilot suicide may have led to the tragic downing of the plane presumably in the southern Indian Ocean.

However, nothing can be ruled out until the black box is found. That possibility grows increasingly remote as time drags on. MH370 disappeared on 3 Mar 2014 during a routine Kuala Lumpur to Beijing flight with 239 passengers and crew on board.

The Australian quoted Dan O’Malley of the Australian Transport Safety Bureau as saying: “The limited evidence available for MH370 was compared with three accident classes: an in-flight upset, an unresponsive crew/hypoxia event, and a glide event [generally characterized by a pilot-controlled glide].”

The leading theory held by investigators is a so-called hypoxia event i.e. a dip in oxygen in the cabin causing the crew to lose both consciousness and control of the plane.

“The pilot suicide theory for Flight MH370 gained traction because, throughout the last year, there’s been no evidence of an outside plot,” according to aviation writer Sylvia Spruck Wrigley in BBC News recently.

The first clue on what may have happened to MH370 emerged when a flaperon, a part of the wing, washed up on Reunion Island in the western Indian Ocean recently. Since then, investigators have been puzzled by what actually happened to the plane.