How satellites tracked down flight MH370 – but why we still can’t find the plane (updated)

• By Sebastian Anthony on March 27, 2014 at 11:10 am
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Updated @ 11:10 March 27: Thailand’s Thaicote satellite has spotted another 300 objects in the Indian Ocean, about 200 kilometers (120 miles) south of the objects spotted by the French satellite. This new imagery was captured on March 24, one day after the French data. Earlier today, the 11 search-and-rescue aircraft were called off after just a couple of hours due to bad weather and zero visibility. We still haven’t physically located any of the objects spotted by satellites — and due to bad weather and strong currents, it may be some time until we finally track down the debris of flight MH370.

300 new objects, spotted by the Thaichote satellite

The MH370 search area, on March 27 [Image credit: BBC]

 Updated @ 10:45 March 26: 122 objects, possibly debris from flight MH370, have been identified in new satellite imagery captured by the French company Airbus Defence and Space. The objects are up to 23 meters (75 feet) in length, and are spread out over an area of 400 square kilometers. Australian search-and-rescue planes today checked the areas highlighted by the satellite imagery, but left without finding anything. There is still no sign of oil slicks or floating debris that would help pinpoint the wreckage of flight MH370. As you can see in the image below, we’re searching tens of thousands of square kilometers for signs of debris — using just seven military and five civilian planes, and a few ships (but they cover a very small area, very slowly).
Suffice it to say, I would not be surprised if we never find the remains of flight MH370.

The 122 new bits of possible MH370 debris

The original story, about how we tracked flight 370 to its crash landing in the Indian Ocean, continues below.
Yesterday morning, the Malaysian prime minister confirmed that Malaysia Airlines flight 370 crashed in the south Indian Ocean, killing all 239 people on board. Curiously, though, despite the PM’s confidence, this conclusion is based entirely on second-hand information provided by UK satellite company Inmarsat. There is still no sign of debris from MH370, and investigators still have absolutely no idea what happened after the final “All right, good night” message from the cockpit. If you’ve been following the news, you probably have two questions: How did Inmarsat narrow down MH370′s location from two very broad swaths across central Asia and the Indian Ocean, and furthermore, if we know where the plane crashed into the ocean, why haven’t we found it yet?

How Inmarsat tracked down flight MH370

After flight MH370′s communication systems were disabled (it’s still believed that they were disabled manually by the pilots, but we don’t know why), the only contact made by the plane was a series of pings to Inmarsat 4-F1, a communications satellite that orbits about 22,000 miles above the Indian Ocean.
The initial Inmarsat report, which placed MH370 along two possible arcs, was based on a fairly rudimentary analysis of ping latency. Inmarsat 4-F1 sits almost perfectly stationary above the equator, at 64 degrees east longitude. By calculating the latency of MH370′s hourly satellite pings, Inmarsat could work out how far away the plane was from the satellite — but it couldn’t say whether the plane went north or south.

A map showing the location of Inmarsat 4-F1, which received Satcom pings from MH370, and the plane’s radius from the satellite (calculated from the “ping” round-trip time).

Inmarsat’s global coverage. The satellite that tracked flight MH370 is shown in purple.

To work out which direction was taken by flight MH370, Inmarsat, working with the UK’s Air Accidents Investigation Branch (AAIB), says it used some clever analysis of the Doppler effect. The Doppler effect describes the change in frequency (the Doppler shift) as a sound/light/radio source travels towards the listener, and then again as it moves away. The most common example is the change in frequency of a police or fire truck siren as it passes you. Radio waves, such as the pings transmitted by flight MH370, are also subject to the Doppler effect.
Basically, Inmarsat 4-F1′s longitude wobbles slightly during its orbit. This wobble, if you know what you’re looking for, creates enough variation in the Doppler shift that objects moving and north and south have slightly different frequencies. (If it didn’t wobble, the Doppler shift would be identical for both routes.) Inmarsat says that it looked at the satellite pings of other flights that have taken similar paths, and confirmed that the Doppler shift measurements for MH370′s pings show an “extraordinary matching” for the southern projected arc over the Indian Ocean. ”By yesterday [we] were able to definitively say that the plane had undoubtedly taken the southern route,” said Inmarsat’s Chris McLaughlin.

A satellite spotted some possible debris off the coast of Australia — but by the time airplanes arrived to check out the scene, the debris had gone.

So, where is flight MH370?

At this point, if we assume that Inmarsat knows what it’s doing, we know with some certainty that flight MH370′s last satellite ping originated from around 2,500 kilometers (1,500 miles) off the west coast of Australia. Because we know how much fuel the Boeing 777 was carrying, we know that it probably ran out of fuel sometime after that last ping, crashing into the Indian Ocean. Assuming the plane was flying at around 450 knots (517 mph, 833 kph), the potential crash zone is huge.
The southern Indian Ocean is one of the most inhospitable and remote places on Earth. Its distance from major air and navy bases make it one of the worst possible places to carry out a search and rescue mission. Even if satellite imagery purports to show debris from flight 370, waves, weather, and ocean currents mean that the debris will be constantly moving. ”We’re not searching for a needle in a haystack,” said Mark Binskin, vice chief of the Australian Defence Force. “We’re still trying to define where the haystack is.”
Multiple nations are sending search-and-rescue aircraft and ships to the region to look for flight 370, and the US is deploying its Towed Pinger Locator — a device that can locate black boxes up to a depth of 20,000 feet (6,100 meters). The flight data recorder (FDR) or cockpit voice recorder (CVR) generally only have enough battery power to ping for a month or two, so time is of the essence.

What happened to flight MH370?

So, the million dollar question remains: What series of events led to Malaysia Airlines flight 370 ending up in the Indian Ocean?
There appear to be two likely options. The most pertinent point still seems to be that the plane’s ACARS (automated reporting system) was manually disabled. This would indicate that the plane was either hijacked, or that the ACARS had to be disabled for some other reason (a fire). It’s possible that there was some kind of disaster on-board, killing or disabling everyone, and the plane continued on auto-pilot until it ran out of fuel. It’s also possible that the plane was hijacked (perhaps by a passenger or one of the pilots), and they continued to fly the plane on some kind of suicide mission.
Neither of these explanations quite ring true, but really, given the dearth of information, it’s the best that we can do. At this point though, we should be terrified of another eventuality: Given where the plane crashed, we may never find the flight data recorder (FDR) or cockpit voice recorder (CVR) — theorizing about the fate of flight 370 might be all we can ever do.