Satellite-enabled signaling by aircraft transiting oceanic routes offers a near-term solution to curbing aviation emissions, asserts a Purdue University study. Aireon, the joint venture developing a space-based surveillance system based on automatic dependent surveillance-broadcast (ADS-B) position reporting, funded the study by Purdue’s school of aeronautics and astronautics.
Beyond the reach of land-based radar, aircraft flying on oceanic routes must report their position by satellite link or HF voice radio when they arrive at predetermined waypoints. With less frequent information on the whereabouts of such aircraft, air navigation service providers (Ansps) keep them separated laterally by 50 nm and longitudinally (in trail) by 10 minutes, or about 80 nm.
Space-based ADS-B, a system using transponders mounted on satellites, will enable aircraft to constantly signal their position over remote expanses, creating a picture comparable to radar-controlled airspace. Ansps will be able to reduce separations of ADS-B-equipped aircraft to 15 nm laterally and 15 nm in trail, according to the study—freeing up airspace to accommodate optimal altitudes, speeds and routes.
More efficient routing and operations will have the concomitant effect of limiting greenhouse-gas emissions, giving the aviation industry a nearer term solution to addressing its environmental goals than introducing new engines and aircraft and producing sustainable aviation biofuels at commercial scale. According to the report, Federal Aviation Administration and industry analyses have determined that average fuel savings of 30-to-38 kg per flight would result if 86 percent of aircraft transiting New York Oceanic airspace were allowed to fly at 15/15 nm separations. Similar, proportional benefits would result in Pacific and Arctic oceanic airspace, where the distances are larger.
“Space-based ADS-B will reduce lateral and longitudinal separation, increase access to preferred altitudes and allow fuel-saving speed changes for the majority of aircraft crossing the Atlantic,” states the report, which Aireon released on December 21. Once in place, the system could help airlines save on average “about 2 percent” in fuel in currently unsurveiled oceanic and remote airspaces, it concludes.
The Aireon joint venture consists of mobile satellite services provider Iridium Communications, launch customer Nav Canada and the Ansps of Ireland, Italy and Denmark. Plans call for Nav Canada to acquire a 51 percent controlling interest in Aireon by late next year.
The partners will administer a surveillance network constructed of ADS-B payloads hosted on the new Iridium Next generation of 66 low-earth-orbit satellites. Earlier plans called for activating the system next year, but Aireon has pushed the start date to 2018 with the delayed deployment of the Iridium Next constellation. The first 10 satellites were scheduled to launch on December 16 aboard a SpaceX Falcon 9 rocket, but the launch date has been postponed to early January. SpaceX said it needs more time to complete its investigation of a September 1 explosion that destroyed a Falcon 9 at Cape Canaveral Air Station, Florida, causing it to ground the fleet.