The case of the missing plane remains an excruciating mystery, and the only thing authorities are saying with confidence is that Malaysia Airlines Flight 370 went south instead of north, flying almost halfway to Antarctica before crashing somewhere in a remote expanse of the southern Indian Ocean.
Even that conclusion, which is problematically vague for searchers, is propped up by delicate satellite data that required two weeks of interpretation. Small changes in initial assumptions about the plane’s speed produce large differences — many hundreds of miles — in the calculated outcomes.
Debris in that lightly traveled expanse of ocean has been sighted by satellites and aircraft, but there is no evidence that it has any connection to the missing plane. Military searchers in surveillance aircraft are battling brutal weather; clouds are hampering satellite searches and NASA’s efforts to spot debris with a camera on the international space station.
Time is precious. Military vessels are on the way with instruments that could pick up the ping of the aircraft’s “black box” flight data recorder on the sea floor, but the pinger’s batteries typically last only 30 days.
“This is really uncharted territory. Usually you have plenty of data to work with — black boxes, voice recorder and lots of satellite telemetry. Everyone is working pretty much in the blind,” said Scott Madry, a satellite expert at the International Space University in Strasbourg, France.
The jetliner, a red-eye from Kuala Lumpur to Beijing with 239 people aboard, vanished March 8 with no hint of distress or any sign of an explosion or hijacking. Radar picked up signs of the plane turning around and heading west, back across the Malaysian peninsula into the Strait of Malacca.
There are many scenarios for what happened in that first hour after takeoff, ranging from a fire to a sudden decompression to a hijacking to a diversion carried out by a member of the crew. There is still no solid evidence supporting any particular narrative.
There is, however, a new consensus among investigators that the plane turned again sharply to the south and, for whatever reason, flew steadily across the uninhabited reaches of the open ocean until it ran out of fuel and crashed.
Malaysian Prime Minister Najib Razak announced Monday that the flight had “ended” in the southern Indian Ocean, and on Tuesday the government released background materials to justify that conclusion — instantly generating controversy.
The new flight-path analysis emerged from data gathered by the British satellite company Inmarsat. The company has a satellite in a geostationary orbit, hovering 22,000 miles above the equator over the Indian Ocean. Once an hour, a ground-based radio antenna had a “handshake” with a computer on the plane, with the transmission relayed by the satellite.
The first computer handshake came when the plane was still at the gate in Kuala Lumpur. After the plane vanished, the ground station and plane had six more hourly handshakes, indicating that the plane was still flying.
Inmarsat’s scientists studied those signals and looked for subtle changes — a Doppler shift in the frequency — that would indicate whether the plane was flying toward or away from the satellite, according to a statement released Tuesday by the Malaysian government and attributed to the British Air Accidents Investigation Branch.
The analysis indicated that the plane flew away from the satellite in a corridor to the north or a corridor to the south. Then, in recent days, the analysts developed a theoretical model for what the signals ought to look like in each flight corridor. They examined flight data and changes in frequencies from half a dozen other Boeing 777s flying on the same night that MH370 vanished. The transmissions from MH370 matched the predictions for signals coming from a plane flying on the southern corridor.
Still, that analysis did not reveal precisely which southerly route the plane took. The final location of the plane would depend in part on its speed.
A graphic produced by the British investigators shows two potential flight paths, one if the plane was flying at 450 nautical miles per hour and another if it was going only 400 — both of them plausible speeds for a Boeing 777 cruising on autopilot.
The two paths veer apart hour by hour. The lines on the map end at points where the plane may have been at 8:11 a.m., Malaysia time, when the plane and satellite had their last handshake. The plane could have flown a bit farther after that. The two conjectured locations of the final handshake are roughly 1,000 kilometers (621 miles) apart, estimated Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics and an expert on satellites.
“In terms of finding the debris, you’d really like to narrow it down to a hundred miles or so, and you can’t do that, because small changes in assumptions about the airplane’s speed are going to change the search area by thousands of miles,” McDowell said. “All this analysis does is tell you that, yes, it is in the southern Indian Ocean, it’s on the southern track, it’s west of Australia. But how far west, how far south, we can’t do that.”
He added, “What this whole experience is bringing home to people is how big this planet is and how much of it is empty ocean.”
The Malaysian government said further analysis will attempt to refine the likely location of the plane when it made its final handshake.
Another anomaly surfaced Tuesday: The satellite information indicated a possible “partial” handshake eight minutes after the final full handshake. Investigators have no explanation for this.
“Why was it only partial?” Madry asked. “If there was a fire aboard the plane, it could have burned through the electrical power. Or it could have been when the aircraft impacted. That’s less conceivable. Something happened on that aircraft to allow this partial handshake. Was it an anomaly? It’s just a microsecond burst. It could have been an electrical failure. It could have been a fire.”
The British investigators did not state explicitly that the plane crashed. Instead, the official statement sticks to what is known about the plane’s ultimate silence. There was no response from the plane when, an hour and four minutes after the last full handshake, the ground station sent the next message to the plane.
“This indicates that the aircraft was no longer logged on to the network,” the investigators said.
They concluded that the plane was no longer able to communicate.
“This is consistent with the maximum endurance of the aircraft.”
Jia Lynn Yang in Kuala Lumpur and Ashley Halsey III in Washington contributed to this report.