A CONSTELLATION of next-generation communications satellites has a surprise in store for the environment. When Iridium Communications begins launching replacement orbiters in 2015, it will do much more than upgrade its satphone services. Piggybacking on the satellites will be a set of transmitters that could revolutionise long-haul flight, save airlines billions of dollars worth of fuel and prevent millions of tonnes of carbon emissions.
For the first time, these devices, known as ADS-B transponders, will enable air traffic controllers to locate aircraft that are far out over oceans, remote deserts or the poles where there is no radar coverage. On top of the greater safety this offers airlines if a plane gets into trouble, say, it will also let controllers pack planes in closer together along optimal flight paths, which will cut carbon emissions.
The ADS-B radio transmitting system is designed to replace expensive, unreliable and low-range radar tracking. It bundles an aircraft's call sign, GPS position, speed and altitude into 112-bit digital packets, which are broadcast continually from the aircraft to the control stations.
But like today's radar, ADS-B radio packets have limited range. "If you're way out in the Pacific or over the North Pole no one's going to pick it up," says Dan Mercer of Iridium Communications. So the transponders piggybacking on the new satellites will pick up those signals and beam them back down to Earth. "For the first time, they'll have total vision of the aircraft at all times," Mercer says.
To avoid potential collisions, planes on long-haul routes out over the oceans currently have to fly quite a long way apart. And only some planes can fly in air lanes with kind tailwinds, while others have to push through less-favourable air currents. "If air traffic control can see where aircraft are precisely, they can fly them all closer together and on the most efficient routes. So they will save fuel and cut emissions," says Mercer.
A study commissioned by Iridium found that between the service's proposed start in 2017 and 2030, the technology should save airlines about $7 billion on fuel and cut carbon dioxide and nitrogen oxide emissions by 35 million tonnes. Another projection that looked at just North Atlantic flights says orbital ADS-B will save airlines $110 million in fuel and 300,000 tonnes in emissions in 2018 alone.
The system can "improve the efficiency of oceanic air traffic management by reducing aircraft separation distances and allowing greater route optimisation", says Pauline Lamb, operations director of National Air Traffic Services in Prestwick, UK. She adds that her organisation is working to fully understand the benefits it will provide.
Meanwhile, one of the world's largest air traffic management firms, Nav Canada of Ottawa, Ontario, has formed Aireon, a joint venture with Iridium. Aireon will operate and sell the transponder service to airlines and air traffic control providers. In combination with other measures - such as use of lighter carbon fibre planes and more efficient engines - Iridium's move should help aviation fight its environmental corner.
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Satellite upgrade should let planes slash emissions
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Satellite upgrade should let planes slash emissions
