How Flight MH370 could vanish without a trace

The world’s oceans remain gaping blind spots for air traffic controllers, and systems to accurately track planes offshore are years away

Jason Lee/Reuters

Jason Lee/Reuters

On Wednesday, Malaysian police chief Khalid Abu Bakar told reporters that the investigation into the disappearance of Malaysia Airlines Flight MH370 could “go on and on and on” and that, at the end, investigators may never know the true cause of the tragedy. Chris Sorensen explains why this may be the case. This article was first published on March 21, 2014.

For well over a week, what investigators knew—actually knew—about the disappearance of Malaysia Airlines Flight MH370 could be scribbled on a cocktail napkin. The Boeing 777 left Kuala Lumpur International Airport at 12:41 a.m. local time on March 8, bound for Beijing. There were 239 people aboard, including 12 crew members. The plane had about eight hours worth of fuel in its wings. The last communication from the cockpit occurred at 1:19 a.m., when someone, believed to be co-pilot Fariq Abdul Hamid, calmly told controllers, “All right, good night.” The plane then left Malaysian airspace and vanished from controllers’ screens.

After that, things got muddy in a hurry. Officials say the plane’s transponders, used to identify the flight to controllers on the ground, were shut off at 1:21 a.m. A messaging system called ACARS (Aircraft Communications Addressing and Reporting System) that sends data about the plane’s systems was similarly disabled around the same time. There were indications, based on military radar, that Flight 370 banked to the west after ground controllers lost contact, climbed quickly to 45,000 feet and then descended unevenly before heading northwest toward the Indian Ocean. The 777 may have been in the air for as long as seven hours after that last sighting, but investigators don’t know which direction it was flying. Clues gleaned from brief, automated contacts sent to a nearby satellite have “narrowed” the possible last known location of Flight 370 to two huge arcs covering an area about the size of the continental United States—one that curves upward from Thailand to the border of Kazakhstan and Turkmenistan, and another that extends into the middle of the Indian Ocean, as far south as Perth, Australia.

With some 25 countries involved in the hunt for Flight 370, the plane’s disappearance quickly became one of the most bizarre mysteries in modern aviation. At various times, the theories about what might have happened to Flight 370 included: a fire on board, a mid-air explosion, a meteor strike, a hijacking, a pilot suicide or even a James Bond-like plot to steal the airplane and fly it at 5,000 feet above the water to avoid military radar detection, to a secret location.

But regardless of what transpired, the most troubling element of Flight 370’s disappearance is that investigators had no idea where to begin looking for it. “This is very unusual to have something just go missing without a trace,” says Sunjoo Advani, an expert in flight simulation who’s been working with a team to improve pilot training in the wake of the industry’s previous big accident, the 2009 crash of Air France Flight 447. “We can’t lose airplanes. We can’t let airplanes just disappear on us.”

Indeed, questions are already being asked about the way air traffic control systems track the roughly 90,000 flights that criss-cross the globe every day. How is it possible, many have asked, to simply lose a US$261-million airplane—one of the biggest twin-engined commercial jets in the world—in an age of GPS-equipped smartphones that tell your friends which restaurant you’re dining in?

Despite all the technological advances, including planes that can basically fly themselves, a surprising amount of long-haul flying is done well beyond the eyes and ears of air traffic controllers—particularly over oceans, which largely remain gaping blind spots. At present, the global system that tracks commercial flights relies heavily on radar, a Second World War-era technology. Such systems suffer from a lack of range—about 200 nautical miles for a plane travelling at 35,000 feet—and are therefore of little use beyond a country’s shores. Moreover, there’s little equipment on a modern airliner that can’t be turned off or tampered with, including the transponders and other communication systems.

Only relatively recently have countries begun work on comprehensive satellite-based tracking systems to figure out exactly where planes are flying over open water. Canada’s air navigation services provider, Nav Canada, is one of several partners in a project that aims to provide near worldwide, real-time surveillance of commercial flights. But it won’t be up and running until 2018 at the earliest, and it remains to be seen whether there will be calls to make such transponder equipment tamper-proof. Either way, it’s of no use for the 239 people aboard Flight 370 and hundreds of their family and friends who are still wondering: what in the world happened?

It didn’t take long for the hunt for Flight 370 to dissolve into confusion and chaos. Teams from Malaysia, Singapore and Vietnam scoured the water along the plane’s intended route for signs of wreckage. Promising leads evaporated as quickly as they appeared. Reports of oil slicks near an island off the coast of Vietnam turned out to be fuel left behind by a ship. A potential life raft sighting was actually cable reel covered with moss. A Chinese satellite photo of a piece of floating debris yielded nothing but empty water when investigators arrived on scene. Millions of armchair volunteers scoured other satellite photos posted on the website Tomnod. The ocean, they soon realized, was an impressively big place.

Within a few days of the plane’s disappearance, a separate and equally muddled narrative emerged about the possibility of terrorist involvement. Early on in the investigation, an Italian and an Austrian came forward to inform authorities they had not flown on the plane, despite being listed on the manifest. Closed-circuit video footage of the two Iranians who used their passports was released, though it later emerged that the two were likely asylum seekers, not terrorists, reported London newspaper the Guardian.

Answers to some very basic questions—did the plane go down? Did it fly somewhere other than Beijing?—might have been easier to come by if flight controllers had been able to continue monitoring the flight’s progress in real time. But in Malaysia, as is the case in most other parts of the world, it’s not nearly that straightforward.

When it comes to real-time surveillance of the air—meaning detecting objects in your airspace whether they want to be seen or not—the only tool currently at the disposal of air traffic controllers is primary radar, which sends out radio waves and waits for them to hit something and bounce back. Such systems are used mostly by the military to search for intruders, or by air traffic controllers charged with making sure unwelcome objects—hang gliders, weather balloons—don’t wander into a busy, off-limits airspace.

However, primary radar doesn’t tell controllers much about what they’re looking at—a plane or a flock of birds. For more specific information, the industry relies on so-called secondary radar systems that couple ground-based arrays with aircraft-mounted transponders. In addition to signalling a plane’s presence, transponders send back radio signals that include the plane’s flight number, altitude and speed. (In the case of Flight 370, the plane was still within range of the secondary radar system’s 200-nautical-mile limit when controllers lost contact, leading them to believe the transponder was turned off for some reason.)

Things get infinitely more difficult when trying to track a plane flying over the open ocean. With nowhere to set up radar stations, airlines and air traffic controllers are forced to take educated guesses as to where, exactly, a jet is flying along its predetermined path at any given moment. In the old days, this was done by having the pilot periodically call in his position over high-frequency radio. Needless to say, there was plenty of room for error, which is why planes were typically spaced out 10 minutes apart, or the equivalent of about 60 nautical miles, on busy oceanic routes, according to Rudy Kellar, Nav Canada’s executive vice-president of service delivery.

Starting about seven years ago, Kellar says, the industry began utilizing a type of satellite communication to get a better idea of where planes were flying over the North Atlantic, the world’s busiest oceanic corridor with more than 350,000 flights traversing it every year. The system, called ADS-C (automatic dependent surveillance-contract) requires the cockpit’s computers to pull the plane’s GPS coordinates from a satellite and then relay them to the ground via another satellite. The extra data, combined with traditional radar and other land-based tracking systems installed in Greenland, allow controllers to safely put planes on the track about five minutes apart, or the equivalent of 30 nautical miles, Kellar says.

The same network also transmits ACARS data. In the case of Flight 370, the ACARS system was set up to transmit data about the performance of the engines to manufacturer Rolls-Royce, but was turned off along with the transponder. Even so, the system continued to send out “pings” to a nearby satellite (not unlike how your cellphone routinely makes contact with nearby towers so incoming phone calls can be properly routed) that allowed investigators to determine Flight 370 had actually kept flying for several hours after controllers lost contact with it.

Damir Sagolj/Reuters

Damir Sagolj/Reuters

And so, Flight 370 was essentially invisible to civilian air traffic controllers once its transponders were turned off (either by accident or intentionally). Even if they had been left on, they would have been nearly useless in locating the plane once it travelled 200 nautical miles offshore, which is beyond the reach of most primary radar systems. Nor is it clear whether ADS-C data would have made it much easier to figure out exactly where the plane was flying once it headed out over the Indian Ocean. “We get a message every 15 or 20 minutes,” says Kellar in the case of the North Atlantic. “So, in that time frame, we’re monitoring where we predict that airplane will be and then we’re validating that estimate when we get the actual report.” Kellar adds there’s a simple reason why ADS-C does not provide more frequent, by-the-second updates: “It would cost a crazy amount of money.”

Without location data from Flight 370 itself, investigators were forced to piece together clues about the plane’s whereabouts from other sources, including military radar and the ACARS “pings.” Hence, the first indications that the plane had veered wildly off course didn’t emerge until March 11, three days after it disappeared. That’s when Malaysia Airlines suggested the pilots may have tried to turn the plane back toward Malaysia. The Guardian reported that the chief of the country’s air force said the plane may have been detected by military radar around 2:40 a.m. near Pulau Perak, an island in the Strait of Malacca on the opposite side of the country. Two days later, the Wall Street Journal cited U.S. sources who suggested the Boeing 777 had flown for hours after its last reported contact, based on the ACARS satellite pings that had been received. The theory was initially rebuffed by Malaysian officials and then later confirmed by the satellite company itself. “Routine, automated signals were registered on the Inmarsat network from Malaysia Airlines Flight MH370 during its flight from Kuala Lumpur,” Inmarsat said in a statement.

In the days that followed, the search zone ballooned to include both central Asia and the southern part of the Indian Ocean, based on the satellite pings. More satellites were directed overhead. Dozens of other countries became involved. The investigation swung to focus on the pilots as it increasingly appeared as though it was possible someone with a deep knowledge of the 777 had deliberately turned off its various transponders and other identifying systems to avoid detection. (Patrick Smith, of the popular Ask The Pilot website, pointed out in a recent blog post that “very few of a plane’s components are hot-wired to be, as you might say, ‘always on,’ ” and are designed to be isolated and turned off in the event of a fire.) Key to this theory was the supposed order in which things went offline. Early in the week, Malaysia’s defence minister said the ACARS system was disabled before the co-pilot’s last message to ground controllers, which would be an unlikely sequence of events if the system went down as a result of a problem in the cockpit.

Police searched the house of the plane’s captain, 52-year-old Zaharie Ahmad Shah, who had built his own flight simulator and talked about it on online forums. Some newspapers also tried to draw a link between Zaharie’s support of Malaysia’s People’s Justice Party, the group headed by opposition leader Anwar Ibrahim.

With the once remote-seeming possibility of a stolen airplane suddenly looking plausible, experts and cable news reporters raced to explain how a plane could fly for hours undetected through the airspace of some of the most militarized nations in the world. Perhaps whoever was behind the controls flew below 5,000 feet to defeat the radar systems? A spokesperson for the Pakistan Taliban denied responsibility for the disappearance of Flight 370, telling Reuters, “We wish we had an opportunity to hijack such a plane.”

At the other end of the spectrum, a post on Google’s social media site by a former pilot suggested the possibility that Flight 370 was stricken by a simple cockpit fire. Under that scenario, the flight crew may have tried to change course in an attempt to reach the nearest airport with a sizable runway—perhaps at Langkawi, an island off the west coast of Malaysia—before they were overcome by smoke. The rapid changes in altitude recorded could have been an attempt to starve the fire of oxygen; the disconnected transponders an attempt to isolate an electrical fire. The autopilot could have conceivably continued flying the plane until it ran out of fuel over the Indian Ocean.

To add to the already considerable confusion, the CEO of Malaysia Airlines on Monday backed away from assertions that the final voice message from the cockpit followed the disabling of the ACARS system, noting that the last scheduled transmission was at 1:07 a.m. and that another transmission wasn’t expected for a half hour—meaning investigators didn’t actually know whether the ACARS system was switched off before or after the co-pilot’s final words.

There is no quick fix to the dated, patchwork air traffic monitoring systems now in use. While countries around the world are spending billions to upgrade their existing technology, the current goal is driven by economics, not safety—namely finding ways to cram more planes into the skies overhead.

The U.S. is rolling out a new “NextGen” system using a technology called ADS-B (automatic dependent surveillance-broadcast) that uses a type of radio transponder system to broadcast information about a plane’s flight number and position to antennas on the ground. Australia, Canada and several other countries have already made similar upgrades. The advantages for airlines and air traffic controllers are numerous: lower cost, greater range and more accurate positioning (thanks to GPS). The signals can also be picked up by other pilots.

But, in its current form, ADS-B functions a lot like existing secondary radar systems, with the key difference being that planes are continually broadcasting their position instead of waiting to be interrogated by radar. And there are indications that ADS-B was already up and running in the Gulf of Thailand, where Flight 370 first disappeared. Websites like, which track ADS-B broadcasts, lost contact with Flight 370 at around the same time as air traffic controllers back in Malaysia did. Moreover, like radar, current ADS-B systems do not provide coverage over the ocean because of the need for antennas on the ground to relay data. (The U.S. FAA has, however, mounted receivers on oil platforms in the Gulf of Mexico, providing real-time flight tracking over that busy body of water for the first time ever.)

There is a potential solution on the horizon. Two years ago, Nav Canada signed a $150-million partnership deal with communications satellite company Iridium, which is scheduled to begin launching a new network of 66 communications satellites next year. The agreement, which involved the formation of a company called Aireon, will allow ADS-B receivers to piggyback on the new satellites, making it possible to monitor air traffic anywhere around world for the first time in history, including over oceans or desolate regions like Canada’s Far North. Air navigation providers in Italy, Denmark and Ireland have since signed on as partners. “The main challenge in many people’s minds was, could you finance an entire constellation of satellites just to receive airplane signals? That’s why the Aireon was such a unique opportunity for the world,” Kellar says. “It’s a game changer.”

Kellar estimates that the space-based ADS-B system will allow for a separation of 15 nautical miles between transatlantic flights, translating into savings for airlines on the North Atlantic route of about $120 million a year. But it’s also clear, in the wake of Flight 370, that there may be interest in such a system simply to keep tabs on airplanes around the world—particularly if combined with new requirements for an always-on transponder system. Kellar says the system should be available for the North Atlantic by 2018.

In the meantime, it’s been a tortuous few weeks for the families of Flight 370’s missing. In Beijing, Malaysia Airlines recently invited family members to private daily updates on the search at the Lido Hotel, but the meetings did little to satisfy them. One of the few relatives who agreed to speak was Wen, the wife of a Chinese passenger aboard Flight 370 (she only offered her surname, and refused to fully identify her husband). “The information they gave us was useless, and a lot of it was confusing,” she said of the jargon-heavy briefings that lacked any concrete new details. Other relatives were also angry. “We’ve lost confidence in Malaysia Airlines,” said a man from Shandong province, who also refused to give his name. “We think they aren’t telling the truth. We want to hear the whole story.”

The truth? Nobody knows.

—with Kyle Mullin

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