Malaysian Air Flight 370’s disappearance became the longest in modern commercial aviation as investigators lacking new information to back other theories explored the possibility of pilot suicide.

Whoever was operating the plane went to great lengths to avoid being detected, shutting off the plane’s transponder beacon and a text-to-ground messaging system before turning the Boeing Co. 777-200 off its course to Beijing from Kuala Lumpur. While not ruling out hijacking or sabotage, Malaysian officials said they had to investigate the pilots.

“Yes, we’re looking at it,” Acting Transport Minister Datuk Seri Hishammuddin Tun Hussein said at a press conference in Kuala Lumpur yesterday referring to a question about pilot suicide.

The longest period in modern passenger-airline history between a disappearance and initial findings of debris was seven years ago, when Adam Air Flight 574 went missing off the coast of Indonesia’s South Sulawesi. The Boeing 737-400, operated by PT Adam Skyconnection Airlines, lost contact with air traffic control Jan. 1, 2007. Wreckage wasn’t found until 10 days later.

U.S. officials have said the most likely location of Flight 370’s final satellite transmission was over the Indian Ocean in a zone around 1,000 miles (1,600 kilometers) west of Perth, Australia, an area with some of the world’s deepest and most forbidding underwater terrain.


‘Most Probable’


The “most probable” theory is the plane carrying 239 people is beneath the ocean, though there isn’t physical evidence to make that conclusion, U.S. Representative Mike Rogers, a Michigan Republican and chairman of the House Intelligence Committee, said March 16.

That area is “in the middle of nowhere, more or less,” said Rhys Arangio, operations and compliance officer for Austral Fisheries Pty., a Perth-based seafood company.

Satellite pings that weren’t turned off showed Malaysia Airlines Flight 370 operated for almost seven hours after last making contact on March 8, Malaysia Prime Minister Najib Razak has said. That may have taken the plane more than 3,000 miles from where it was last tracked and pushed it to the limits of its fuel load, if it was airborne the whole period.

The search for the missing airliner faces four enormous obstacles -- the absence of fresh clues, the time that’s passed, the distance from the nearest air and naval bases and the size of the area to be searched -- said a U.S. intelligence official with search and rescue experience.


'Australia, U.S.'


A lesser possibility being explored is a northern route over land toward Kazakhstan, though U.S. officials and radar experts said the jetliner probably couldn’t have passed through Indian or Chinese airspace undetected.

The U.S. Navy ended its search effort in the Andaman Sea and moved a P-8A Poseidon reconnaissance plane to Western Australia to better support the search effort, Commander William Marks, a spokesman for the Navy’s Seventh Fleet, said yesterday.

Australia started searching the southern Indian Ocean west of Perth with two sweeps over the region today and another due to be made later today, Prime Minister Tony Abbott told parliament. An AP-3C Orion aircraft that had been assisting the search from a base in Cocos Islands southwest of Java was being relocated overnight to the Royal Australian Air Force base in Pearce, near Perth, according to a statement from the Australian maritime Safety Authority today.


'Sparse Population'


The search group was liaising with Australia’s military about whether additional aircraft were available that could operate over long distances in the Southern Ocean, AMSA said.

The area off Perth is “pretty sparsely populated,” with some container shipping from Africa to Australia plying the route as well as tuna fleets and some trawlers, Arangio said.

Storm fronts will bring waves about 10 meters (33 feet) high comparable to those where Austral usually operates, around Heard Island in the Southern Ocean, he said.

“On the average day it may be flat or a few-meter swells,” he said. “If they get lucky, there’s every chance it might not be horrible for a few weeks at a time.”

Even if floating debris is found, it may be difficult to determine an area to begin searching for the crash site, said Mike Purcell, principal engineer at the Woods Hole Oceanographic Institution, which helped locate the so-called black boxes from Air France Flight 447 after it crashed into the Atlantic Ocean off Brazil in 2009.


'Not Easy'


“It’s not easy and it gets harder the longer the time goes by,” said Purcell, a leader of the search expedition. “Things will have drifted farther and farther the longer we have to wait.”

Searchers will try to listen for sound-producing pingers attached to the plane’s black boxes that emit signals for 30 days after becoming immersed in water.

It can be difficult to hear the pingers if they are blocked by undersea mountains, said Dave Gallo, director of special projects for the Woods Hole Oceanographic Institution in Massachusetts, in an interview. Layers of water with different temperatures can also block sounds, he said.

While the black boxes are designed to operate at depths of 20,000 feet (3.8 miles) and may work in even deeper water, the range of the pings is a mile, according to manuals from Honeywell International Inc., the maker of the equipment. That may make the signals difficult to pick up even if an underwater microphone is over the correct location.


'Air France 447'


The emergency locator transmitters on a 777 are designed for land and don’t work underwater, nor do the satellite transmissions that investigators have used to triangulate the likely last-known location.

In the search for Air France 447 wreckage, authorities were able to narrow down a 5,000 nautical-mile area after finding floating objects five days following the crash. They also had a last known position plus four minutes of signals from the plane’s so-called Acars system, which was turned off on Flight 370.

Even with those clues, the pings from Flight 447’s recorders weren’t picked up. It took two voyages over almost a two-year period to find the debris field with unmanned underwater vehicles that searched the ocean floor with sonar equipment.

Police searched the homes of the Malaysian flight’s captain, Zaharie Ahmad Shah, and Fariq Abdul Hamid, the first officer, taking a 777 simulator Zaharie had built at his house for experts to examine.


‘Alright Good Night’


Initial investigations indicated that the co-pilot had the last contact with air-traffic controllers, Malaysian Airline System Bhd. Chief Executive Officer Ahmad Jauhari Yahya said yesterday. “Alright, good night” were the last words from the cockpit, which came in at 1:19 a.m. as Malaysian air traffic controllers prepared to hand the plane over to Vietnamese counterparts, he said.

The jet made its last satellite contact at 8:11 a.m. on March 8, according to Najib. Malaysian officials previously said the plane was last tracked by its transponder, a device that helps radar find its location more precisely, at about 1:30 a.m.

The plane’s transponder and the Aircraft Communications Addressing and Reporting System, which transmits text messages and data to and from planes, have multiple redundancies against failure. However, that’s only if they are not turned off from the cockpit, according to a person with knowledge of the plane’s system who wasn not permitted to speak to the press about an ongoing investigation.


'Against Pattern'


The engineers designed back up plans for every conceivable mechanical failure, though not for a scenario when someone intentionally turns off.

The actions on the flight deck indicate a high level of training in aviation and the 777 specifically, Patrick Veillette, a Park City, Utah, commercial pilot who has taught aviation safety, said in an interview.

“We’re not talking about sitting in a simulator or reading a book for an hour,” he said. “This would have required substantial training.”

There have been at least six airline crashes killing a total of 465 people that were caused by intentional actions by airline employees since 1982, according to AviationSafetyNetwork, which tracks accident data.

The most recent example of suicide came late in 2013, when a pilot steered an Embraer E-Jet into the ground in Namibia, killing 33, according to a preliminary report by the Mozambique Civil Aviation Authority.


'EgyptAir'


In 1999, a co-pilot aboard EgyptAir Flight 990 pulled back the power in a Boeing 767 and dove toward the ocean off Massachusetts after the captain left the cockpit to use the restroom.

The one case not involving a pilot was in 1987, when an employee of Pacific Southwest Airlines who had just been fired smuggled a gun aboard a flight and shot the crew, according to the U.S. National Transportation Safety Board.

In all of those cases, unlike the situation with the Malaysia flight, the end came quickly, usually with a dive into the ground. Also, investigators later found evidence of mental inability or high stress in the pilots’ lives, said John Cox, president of Washington-based aviation consulting company Safety Operating Systems, in an interview.

Suicide is rare even among private pilots, with eight recorded between 2003 and 2012, according to a newly published study by the U.S. Federal Aviation Administration.

“This is completely against every other case that I’m aware of that we have seen,” Cox said. -- Bloomberg