A simple way to track aircraft

Tracking aeroplanes is considered prohibitively expensive, but we already have the necessary cost-efficient technology to do it. By Alan Finkel.

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We can track just about anything. You can use a free app to find your missing iPhone; taxi companies track their cabs; parole boards track their wards. So why can’t we track a 200 tonne technological marvel called a jet aeroplane? Despite the likely expenditure of more than $100 million on a massive international search for Malaysia Airlines flight MH370, no one is any the wiser as to where it is.

What we do know is that after the pilots left Malaysian airspace there was no further communication to the outside world. Someone in the cockpit deliberately turned off the transponder that transmits altitude and location whenever the aeroplane is in a radar zone. Unlike the transponder, the black box flight data and cockpit voice recorder cannot be manually switched off so it would have kept gathering data. But unless we can find it, it is destined to keep its secrets forever.

The only reason we can even estimate where the aeroplane might have gone down is because engineers at British telecommunications satellite operator, Inmarsat, performed brilliant mathematical feats on hourly satellite signal “handshakes” that continued to operate automatically.

So why, when it comes to aeroplanes, does 21st century satellite imaging and radar fail to deliver? It’s not a technological limitation, it’s about cost. But there is a simple solution.

Pundits claim it would be prohibitively expensive to track aeroplanes because it would consume too much satellite bandwidth. But that’s based on the assumption that all the data gathered by the black box flight recorder needs to be broadcast in real time, adding up to gigabytes per hour. No need.

That data includes cockpit conversations and readings from every sensor on the aeroplane – critical for sleuthing the cause of a crash, but irrelevant to the task of finding a missing aeroplane.

All that needs to be broadcast to track an aeroplane is its latitude, longitude and altitude – information that could fit into the 140 character limit of a Tweet, and only a hundred thousandth of the bytes recorded per hour by the black box system.

The amount of location data is so small that even if it were sent over the existing satellite communications network the charges per hour would be a few dollars.

At the moment, the best estimate for where MH370 went down covers an area of 100,000 km2 – the size of South Korea. If the searchers knew where the aeroplane was until the last minute of its flight the search area would be merely the size of metropolitan Melbourne.

So let’s imagine that MH370 had carried a simple location transmitter, one that could not be turned off from the cockpit so no pilot or terrorist could interfere with it. It would broadcast just a few hundred characters each minute – enough for a unique flight identifier and location information.

The amount of location data is so small that even if it were sent over the existing satellite communications network the charges per hour would be a few dollars, a grand total of a hundred dollars or so for a long-haul flight.

There are already satellite-connected devices on the market, such as the Aircraft Communications Addressing and Reporting System (ACARS) installed on most commercial aeroplanes. This system is mostly used for air traffic control information and for equipment maintenance data - it is not designed to transmit the location data that would assist
in the critical task of finding a missing aeroplane.

There is no excuse not to institute requirements that commercial airlines immediately fit transmitters broadcasting location information to all their aeroplanes. Often, developers and planners pursue perfection with the unintended result that the target drifts into the distant future. Instead, the “very good” is a better place to start. In that spirit, the immediate goal should be to send simple location data to help searchers find missing planes and their black boxes.

Loftier ambitions to broadcast the black box data itself should be postponed.

As data transfer costs come down, as they always do, the quantity transmitted can be increased, but in the meantime the cost to transmit the essential location data is so low it should not be an impediment.

Of course, mass-produced commercial versions of such a device would be ideal for sailboats, private aeroplanes, balloonists, hikers and other wilderness travellers, potentially saving lives and untold millions of dollars in search and rescue fees.

But these are not the immediate challenge. The immediate challenge is to ensure that never again will a commercial aeroplane disappear leaving no hint as to where it was when disaster struck. The technology is available, it is time for the regulators to act.

Alan finkel 2014b.png?ixlib=rails 2.1
Alan Finkel is an electrical engineer, neuroscientist and Chief Scientist of Australia.
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