When Iridium’s new satellites will start blasting into orbit next year on top of SpaceX and Dnepr rockets, they’ll be carrying a special payload: an aircraft tracking system that will be able to locate a plane anywhere in the world once Iridium’s 66-satellite constellation is fully operational in 2017.

The service is run by Aireon, a joint venture between [company]Iridium[/company] and government aviation agencies in Canada and Europe, and it plans on charging airlines for its core flight monitoring services. But Aireon said it would open the network up gratis to international rescue agencies during emergencies, allowing them to home in on missing aircraft.

In the case of Malaysia Airlines 370, which disappeared in March, the emergency service could have helped in locating and the possible rescue of the still-missing flight by plotting its exact GPS coordinates every few seconds. The technology behind it is called Automatic Dependent Surveillance-Broadcast