False leads set back hunt for missing Malaysian jet

Sepang, Malaysia: The mystery of Malaysia Airlines Flight MH370 deepened on Monday when a sweeping search failed to find any sign of the jetliner near its last known location, leaving experts to puzzle over how a Boeing 777 with 239 people aboard could have vanished without a trace.

The search was set back by a number of false leads that seemed to underline how little investigators have been able to pin down about the progress of the flight.(The hunt for flight MH-370: Timeline)

With so little concrete to go on so far, aviation experts explored a number of plausible scenarios to explain the loss of the plane, and investigators said they could not yet conclusively rule out almost any potential cause, including terrorism, hijacking, crew malfeasance, pilot error or mechanical failure. (Stolen passports probed in Malaysian plane mystery; hunt on for Iranian man)

An object bobbing in the Gulf of Thailand that from a distance looked like a life raft turned out to be the lid of a large box, Vietnamese authorities said. An oil slick in Malaysian waters was found not to contain any jet fuel. And what was initially thought to be an aircraft tail floating in the sea was actually "logs tied together," according to a Malaysian official. (Oil slick not from missing Malaysia Airlines plane: official)

The lack of results so far raised questions about whether the ships, planes and helicopters from nine nations that were scouring the waters near the aircraft's last reported location, some of them using highly sophisticated equipment, were looking in the right place.

Arnie Reiner, a retired captain with US Airways and the former chief accident investigator at Pan Am, noted, "If they somehow got turned around or went off course when the thing was going down, it could be 90 or 100 miles away from where the flight data disappeared."

It was not yet known whether the Malaysian plane deviated from its planned flight path or how long the pilots could still fly the aircraft after the last reported contact. After more than two days of fruitless search, Malaysian officials said Monday that they were expanding the search area. (Speculation widens over missing jet's fate as search area expands)

This much seemed clear: The aircraft took off from Kuala Lumpur after midnight on Saturday bound for Beijing and lost contact with ground controllers when it was over the Gulf of Thailand, making its way toward Vietnamese airspace in good weather under a moonless sky. The airline said there was no distress call.

Transponders on commercial airliners automatically report their location, altitude, speed and other data by radio. The last two readings from the devices on Flight MH370 were recorded at 1:21 a.m. local time, some 40 minutes after takeoff, and they did not include altitude, according to Mikael Robertsson of Flightradar24, a Stockholm-based organization that tracks aircraft around the world. Robertsson said that might be coincidence: Readings are often incomplete because of transient interference from other aircraft.

Boeing officials and investigators from the U.S. National Transportation Safety Board began conferring with Malaysian officials about Flight MH370 on Monday, U.S. and Malaysian officials said. The FBI has offered to send agents and forensic specialists to Vietnam, Malaysia and Thailand, but so far those countries have declined the assistance, U.S. law enforcement officials said.

One locus of speculation on Monday was the report from the Malaysian government that two men had boarded the plane using stolen passports from Italy and Austria. It was not clear whether the two men, whom Malaysian officials described only as "not Asian," had anything to do with the plane's disappearance. (Stolen passports probed in Malaysian plane mystery; hunt on for Iranian man)

The men, who were scheduled to connect in Beijing for flights to two different European cities, used one-way tickets issued by a travel agent in the Thai resort city of Pattaya. The police there said they were  booked not by the passengers themselves but by an Iranian man known to the police only as Ali, who ordered them by telephone. Another Iranian man paid for the tickets in cash, and the police questioned that man Monday, according to Supachai Phuikaewkhum, the chief of police in Pattaya.

The Malaysia Airlines plane is not the first modern jet to vanish mysteriously. Searchers sometimes take months to locate crash debris in remote areas, deep water or difficult weather conditions. But the Gulf of Thailand is busy with fishing boats, commercial vessels and natural gas platforms and is no deeper than about 260 feet. By contrast, an Air France flight that disappeared over the Atlantic Ocean in 2009 was recovered from a depth of about 13,000 feet.

Aircraft and surface vessels from several countries have joined the search, among them P-3C Orion military planes whose radar systems are capable of locating floating objects as small as a basketball. In a sign of how uncertain officials are of the plane's whereabouts, a U.S. Orion spent part of Monday searching off the western coast of Malaysia, several hundred miles from the flight's last reported location, officials said.

Three crashes at sea in recent years, including the Air France crash, involved problems with the airplane's equipment for measuring airspeed, a crucial parameter for jet flight. If the plane flies too fast, it can break up; too slow, and it does not generate enough lift to stay in the sky. Modern jets have several systems for measuring airspeed, but when they give conflicting readings, crews sometimes fail to determine correctly which ones to trust.

In the Air France case, involving an Airbus A330, an airspeed instrument called a Pitot tube clogged with ice during flight, and the crew misunderstood what had gone wrong. Two Boeing 757s crashed in 1996 because of Pitot tubes or related static intakes that became blocked on the ground, in one case by an insect nest and the other by protective tape that workers forgot to remove after washing the plane.

Another subject of speculation was the possibility that the plane might have been crashed deliberately by a member of the crew. Several past crashes, including an EgyptAir 767 flying from New York in 2002 and a SilkAir 737 in Indonesia in 1977, were known or believed to have been pilot suicides, and a PSA flight in California in 1987 crashed because a disgruntled mechanic entered the cockpit and shot both pilots.

Aircraft have also been known to break up in midair because of undetected cracks in the fuselage, failures of control systems or wiring flaws. But those problems generally affect older aircraft; the Malaysia Airlines 777 was just 11 years old.

Although officials have not ruled out terrorism in the Malaysia Airlines case, no evidence of foul play has yet come to light. No group has claimed responsibility for downing the plane, although as Reiner noted concerning the 747 that exploded over Lockerbie, Scotland, in 1988, "when Gadhafi's guys blew up Pan Am 103, they weren't talking about it."

By whatever cause, if the missing Malaysia Airlines plane broke up in the air or plunged headlong into the sea, experts said, there ought to be widely strewn debris for searchers to find, but none had yet been spotted by Monday night. That suggested to at least one observer, Robertsson of Flightradar24, that the pilots may have tried an emergency ditching like the one US Airways Flight 1549 managed in the Hudson River in 2009, only to have their aircraft fill with water and sink swiftly afterward. While Flight 1549 ditched on a smooth river in broad daylight, the Malaysia Airlines pilots would have been making the attempt in the dark in the chop of the sea.

There were conflicting views of how well the crisis was being handled by Malaysia. News reports in China, where many of the plane's passengers were from, have been highly critical. But a spokesman for the U.S. 7th Fleet, which has sent two warships to assist in the search, said the Malaysian rescue team was doing a "terrific job of organizing" the effort. (US sends second ship to help search for Malaysia Airlines plane)