MH370: Losing wide-body jet exposes communications gap at 35,000 feet

The silencing of most communications from Flight 370 exposes how easily the voice, radar and satellite links in a modern plane can be disabled. A beacon to help controllers track the jet was shut off. So was the text-and-data system to help Malaysian Airline System Bhd. stay in touch with the crew.

The mystery may spur a redesign of switches that let pilots sever the connections, and speed adoption of satellite technology for real-time tracking of planes and crucial systems, said George Hamlin, a former Airbus SAS executive. Other signals had to be analyzed to trace the jet’s probable last-known location to the Indian Ocean off Australia, two people familiar with the matter said.

“The book of rules is written in blood,” Hamlin said, citing the catchphrase used among aviation professionals. “Many of the rules were written because people discovered how things could go wrong that were unknown before.”

Even a cockpit voice recorder that is part of the so-called black box may not provide telltale clues if the 777-200 operated for four hours after controllers lost contact, as satellite data suggests. The unit keeps only two hours of audio as it overwrites older material in a continuous loop, said Todd Curtis, president of Seattle-based consultant AirSafe.com LLC.

"Off Screens"

Flight 370 last appeared on air controllers’ screens as it neared Vietnamese airspace on March 8 at a cruising altitude of about 35,000 feet (10,700 meters) over the Gulf of Thailand. The last voice communication was normal, according to Malaysia Air.

Before contact was lost, the jet’s radar signature was enhanced by its transponder, which gives air traffic managers details about the target they’re tracking. Pilots can code them to emit distress signals for an emergency or hijacking, said Hans Weber, president of San Diego-based Tecop International, a consultant focusing on aviation safety and security issues.

Malaysia Air’s 777 also was outfitted with the Aircraft Communications Addressing and Reporting System, dubbed Acars, which lets pilots send text message-like communiques to flight operations staff.

The technology allows the jet itself to send reports via satellite or radio to ground handlers of any abnormal performance or mechanical breakdowns. Transmissions to Malaysia Air and engine-maker Rolls-Royce Holdings Plc ceased shortly into flight, the companies said in statements.

Malaysia Air didn’t subscribe to a popular Boeing add-on: a maintenance program to beam real-time information to the Chicago-based planemaker, said a person familiar with the jetliner, who wasn’t authorized to speak on the record. Boeing compiles the data and sends maintenance alerts to participants in its Airplane Health Management program.

Anyone intent on ending aircraft data communications would need to turn a switch to silence the transponder or disable a cockpit circuit-breaker to cut off Acars, said Bill Waldock, professor of safety science who teaches accident investigations at Embry-Riddle Aeronautical University in Prescott, Arizona.

Flight 370’s interrupted Acars data feed indicates intervention by “someone who knows the system on the airplane,” Waldock said. “That has to be the crew or someone who’s intimately familiar with how a 777 operates.”

Even without the flow of Acars reports to the ground, the jet’s position was tracked to near Australia by analyzing pings from a transmitter that signaled a satellite about once an hour after the transponder went dead and the plane veered off its northerly course, said the person familiar with the analysis. The person spoke on condition of not being named because of the sensitivity of the information.

Investigators narrowed the jetliner’s possible routes by mapping the satellite contacts that continued after Acars and other systems were shut down, according to three people familiar with the work.

The pulses provide no data about the plane’s speed, location or altitude. Still, they allow calculations of an arc along the earth’s surface where the plane was each time it communicated with the satellite.

As the industry assesses how to forestall communication gaps in the future, Airbus Group NV and Chicago-based Boeing will have to balance design changes against a host of considerations, from the costs for airlines to the risk of saddling air crews with technology they can’t control.

Requiring more satellite-based flight monitoring may spur objections from airlines about the expense, said Curtis, who worked on the 777’s development as a Boeing employee in the 1990s. Pilots also want to be able to prevent a cockpit fire or short-circuit by pulling the plug on any electronic device, like a transponder or the Acars system, he said.

“Under normal circumstances, in flight you would never shut them off unless you wanted to hide,” said Denny Kelly, a former airline pilot who runs accident-investigation consultant Kelly-James & Associates in Dallas. “Information from the airplane can be a lifeline.”

Hamlin, the former Airbus executive, said one easy fix would be making switches for transponders, cockpit voice recorders and data tracking more cumbersome to turn off.

“If you make things difficult enough, people will go do something else,” said Hamlin, who is president of Fairfax, Virginia-based Hamlin Transportation Consulting.

Wilson Chow, a Boeing spokesman, declined to comment on how Flight 370 might affect aircraft design, as did Mary Anne Greczyn, a U.S. spokeswoman for Toulouse, France-based Airbus Group NV.

Data communications as basic as the aircraft-performance signals sent via Acars were pivotal in unraveling the 2009 Air France jet crash in the South Atlantic.

Messages transmitted automatically as the jet tumbled toward the sea helped point search crews to the disaster zone, even though the pilots never sent a distress call. Five days later, a Brazilian rescue ship began pulling bodies from the sea.

For Flight 370, the cutoff of that data for an unknown period of time leaves a hole in investigators’ understanding of what happened its final moments.

Onboard voice recorders can be disabled by a circuit- breaker in the cockpit, Hamlin said. Curtis, the former Boeing employee, said recovering Flight 370’s recorders also may prove little if the two hours of recording capacity weren’t enough to capture any course change.

“Even if this aircraft is recovered, we may not have answers,” he said. “Passengers’ electronics could be absolutely essential to determine what happened and when it happened.”

Flight 370 is already sparking renewed talk about implementing satellite-based tracking, to span areas beyond radar coverage and provide airlines and controllers more information about what’s occurring in the air.

With technology that’s more advanced than after the Air France crash -- and with the expense of dozens of ships and planes hunting for Malaysia Air debris -- closer monitoring of planes may be an idea whose time is at hand, Weber said. Compiling that data would eliminate the need for data and voice recorders on planes.

The industry discussed the need to stream black-box data after the Air France tragedy. Limited real-time data collection would be possible now at relatively little extra cost as airlines upgrade inflight Internet, said Robert Mann, a former American Airlines executive who heads aviation consultant R.W. Mann & Co. of Port Washington, New York.

“The entire industry is going in the direction of fitting planes with broadband satellite connections for passenger uses and yet for operational purposes they’re kind of stuck in the 1950s,” Mann said.

Richard Aboulafia, an aerospace analyst with Fairfax, Virginia-based consultant Teal Group, said practical limits exist to the redundancies that can be built into aircraft communications. A bedrock premise of aviation is that anyone at the controls of an aircraft would, and should, use all the available safeguards, not actively shun them.