KUALA LUMPUR - Investigations into the mystery of the missing Malaysian jet appeared to be at a deadlock on Wednesday, with an exhaustive background search of the passengers and crew showing nothing untoward and no sign that the plane could be quickly found.
Eleven days have passed since Malaysia Airlines Flight MH370 went missing, and 26 nations are struggling to search for the airliner over an area roughly the size of Australia, or more than two-thirds the size of the United States.
Malaysia's top official in charge of the unprecedented operation said it was vital to reduce the scale of the task and renewed appeals for sensitive military data from its neighbours that Malaysia believes may shed light on the airliner's fate. "All the efforts must be used to actually narrow the corridors that we have announced - I think that is the best approach to do it. Otherwise we are in the realm of speculation again," Malaysia's Acting Transport Minister Hishammuddin Hussein told reporters late on Tuesday.
The US Navy said it had switched mainly to using P-8A Poseidon and P-3 Orion aircraft instead ships and helicopters. "The maritime patrol aircraft are much more suited for this type of operation since the search field is growing," said Navy Lieutenant David Levy, who is on board the USS Blue Ridge, the US Navy ship that is coordinating the search effort. "It's just a much more efficient way to search," he said.
Flight MH370, with 239 people on board, vanished from civilian air traffic control screens off Malaysia's east coast less than an hour after taking off from Kuala Lumpur for Beijing early on March 8.
Investigators piecing together patchy data from military radar and satellites believe that someone turned off vital datalinks and turned west, re-crossing the Malay Peninsula and following a commercial route towards India.
After that, ephemeral pings picked up by one commercial satellite suggest the aircraft flew on for at least six hours, but investigators have very little idea whether it turned north or south, triggering a search expanding across two hemispheres.
Malaysian and US officials believe the aircraft was deliberately diverted, talking down the possibility that an electrical fire could have prompted pilots to turn off electrics before succumbing to the fumes, which has been the subject of widespread online speculation.
US government sources said intelligence agencies had extensively analysed people on the flight but came up with no connections to terrorism or possible criminal motives.
A senior US official said he was "not aware of any stones left unturned".
Unless there is some kind of breakthrough, either in the form of new data or a sighting of the plane, the investigation appears to be drifting towards deadlock, sources said.