For the past few weeks the world's attention has been focussed on the lost Malaysia Airlines plane and its 239 passengers and crew that has apparently crashed in the far reaches of the southern Indian Ocean. Today the air and sea search shifted yet again as fresh radar data suggested the aircraft headed south faster than initially thought, bringing the plane down some 1100 kilometres north-east of the previous search area, putting the crash point 1800 kilometres off Perth, Australia. But just how can we lose a plane in an age of always-on surveillance? Some safety measures are already being put in place, and the UN's International Civil Aviation Organization (ICAO) is considering others.
Flight tracking over the oceans is already possible and it's cheap
That flight MH370 could not be tracked with GPS, when even your walk to the shop can be mapped on a cheap smartphone, is astonishing. Consumer outcry is likely to prompt the ICAO to order mandatory tracking of aircraft over ocean routes.
For 20 years Inmarsat, a satellite telecommunications company, has been tracking every ship on the high seas free of charge for the International Maritime Organization, from which it spun off in 1999. One way it makes money is by selling spare satellite bandwidth to airlines, so they can provide in-flight connectivity anywhere on Earth. Today, says Inmarsat spokesman Jonathan Sinatt, 90 per cent of the world's wide-bodied jets come with Inmarsat antennas built in to the upper fuselage – whether or not the airline operating the plane ultimately uses it.
Malaysia Airlines did not use it for technical data transmission – but even so it has proved extremely useful in the search operation. When the plane's radar transponder and VHF radio link were mysteriously disabled an hour after take-off no one knew where the plane was or where it was heading. But the satellite transmitter still pinged an hourly "I'm still here" handshake signal (with no location data) to Inmarsat's satellite – and those radio pulses that have been used to work out the missing plane's rough flight path south towards the Antarctic.
Pinging location data as well as that handshake signal would have cost just one dollar an hour, says Sinatt: that's 4 pings at 25 cents each. Airlines could pay for more location pings per hour to make tracking resolution finer, too. Other providers of in-flight entertainment and seatback connectivity could do likewise: Panasonic, for instance, offers in-flight broadband and could provide data pings. And the Iridium satellite network is launching 66 new satellites that will provide constant aircraft location data via a service called Aireon from 2017, though prices are not available yet.
But until now there has been no call for complete location data, says Matthew Greaves, head of the air safety and accident investigation unit at Cranfield University in the UK. "Current primary and secondary radar give us the full air traffic control we need to stop aircraft colliding. What we haven't had until now is knowledge of where all aircraft are at all times. We haven't had that motivation before," he says.
Make accident conditions trigger black box data bursts
Why do aircraft flight recorders not routinely stream their data via satellite to cloud servers on the ground? The stumbling block is a lack of affordable satellite bandwidth to transmit the thousands of critical flight parameters that would need transmitting. Even next generation satellite-based in-flight entertainment systems will only deliver 50 megabits per second to an aircraft – and shared between, say, 300 passengers that's a mere 166 kbits/s each.
A much better idea has been hatched by an industry working group led by the BEA, the French accident investigation organisation, after it took two years to find the black boxes from Air France flight 447, which crashed in the Atlantic Ocean in 2009. The BEA's idea is called and its aim is to use avionics software to recognise the signs of an accident in the making – and stream only recent (buffered and real time) black box flight data via satellite. That way only planes in trouble will send out data on their status and location.
To design the system, the BEA-led working group built the world's first database of black box data from 68 previous crashes worldwide. They then worked out the physical parameters that showed each plane was getting into trouble, such as decreased cabin pressure, excessive side-to-side roll, a stall warning sounding or low airspeed. "The algorithm we developed managed a perfect response," says Greaves, a member of the working group. "We triggered on all the accidents with no false positives when it was run against both the accident database and data on normal flights." The algorithm also narrows down the last known location of the aircraft to within 6 nautical miles.
ICAO's flight recorder panel will consider the adoption of the triggered transmission technology in a meeting in Montreal, Canada, in October.
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