New MIT algorithm targets safer skies


July 7, 2011

MIT is developing an algorithm, designed to keep aircraft from being involved in mid-air collisions (Photo: Jakub Halun)

MIT is developing an algorithm, designed to keep aircraft from being involved in mid-air collisions (Photo: Jakub Halun)

Proponents of flying cars like to state how much less likely collisions would be up in the air, where everyone wouldn't be traveling on the same level, yet mid-air collisions between aircraft do already occur. Although certainly not as common as automobile collisions, approximately 10 to 12 aircraft do fly into each other every year, with many more reporting near-misses. This has led to the U.S. Federal Aviation Administration (FAA) mandating that by 2020, all commercial aircraft (and small aircraft flying near airports) must be equipped with a GPS tracking system, which would give more accurate information on their location than is provided by ground-based radar. Scientists from the Massachusetts Institute of Technology (MIT) has been tasked with creating an algorithm, that would use that GPS data to keep the planes out of each other's way.

Using six month's worth of data from San Francisco-area airports, a team led by Maxime Gariel, a postdoc in MIT's International Center for Air Transportation, created a computer system that places virtual horizontal hockey puck-shaped volumes of airspace around aircraft. These pucks represent where an aircraft is likely to go. If the edges of two pucks overlap, the pilots are warned that they're getting too close to one another.

The size of the pucks vary, according to how risky the situation is. Two planes flying parallel in the same direction, for instance, will have relatively small pucks. Once one or both of those planes start to move toward the other, however, their pucks will get larger, in order to provide a warning that much sooner.

To keep pilots from getting tired of receiving too many warnings, the system issues two types: a moderate alert, that lets them know that their current trajectory is intersecting that of another aircraft, and a high alert, that tells them a collision is imminent. Gariel and his team were concerned about the possibility of there being too many false alarms, so the puck algorithm was tested in a computer model, which incorporated air traffic data gathered over eight months from all the aviation radar systems in the U.S. The algorithm reportedly worked well, with a low false alarm rate.

The air traffic model, created at MIT's Lincoln Laboratory, did however have one limitation. All of its data was based on radar, which small aircraft often fly beneath. They particularly do so near airports, which is where 60 percent of midair collisions occur. In response, Gariel's team is now working on another model, that simulates the flight paths that small aircraft tend to follow around airports. They are also looking towards testing the algorithm on real planes.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

I wonder if any of people are pilots?


Once again Soaring/Gliding pilots are way ahead. Its called FLARM a device that does collision avoidance using GPS position and transmission on a private radioband for interdevice communication. It accuratly predicts flightpaths over the next 30 seconds and uses multistage alerts via a led display to alert people of immidiate collisions.

Its been in active use in europe since 1998 and almost all Gliders and SAR Helicopters are equiped with it. (it even has social network capabilites with the combination of There is now an effort that tries to incorporate ADS-B recievers with Flarm in one device called powerflarm.

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TCAS already does this (mostly for larger aircraft), using Mode S transponders to exchange IDs, vectors, etc. Using GPS as one of the data sources is already incorporated into flight control computers. Lots of questions arise about how to handle two different systems: What if one aircraft has TCAS and the other is exclusively this new GPS-only system? How are their resolution advisories to be coordinated? What if they both say \"Descend, descend now\"? Also, how would it interface with ADS-B, etc.?


I would have thought hooking up a GPS chip to a Wi-Fi transmitter/receiver would be much cheaper than transponders. With software controls it could be used to ensure drones never collide and even connected to auto-pilots on GA planes.

The whole transponder/radio thing is so clunky and extremely expensive.

Craig King
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