One Of Two WAAS Satellites Failed


The Wide Area Augmentation System, which broadcasts GPS corrections used by aviators across North America, is powered by just two satellites, and one of them has failed. Intelsat, the company that provides the satellite service to the FAA, lost control of the satellite on April 3. The satellite will “drift out of orbit over the next two to four weeks,” the FAA said on April 12. The most immediate impact will be felt in northwestern Alaska, where service will be unavailable at 16 airports. However, the FAA said that due to the lack of redundant coverage, WAAS users across North America may experience temporary service interruptions. Also, a “single-point failure situation exists until redundancy [is] restored,” the FAA said. A replacement satellite should launch by the end of this year; meanwhile, the FAA is looking at other options to mitigate the impact.

The Government Accountability Office raised questions last year about the lack of redundancy in the GPS system. “It is uncertain whether the Air Force will be able to acquire new satellites in time to maintain current GPS service without interruption,” the GAO report warned. “If not, some military operations and some civilian users could be adversely affected.” Click here for more details about the outage, in an FAA PowerPoint presentation.

At Sun ‘n Fun last week, AVweb raised the issue of satellite redundancy with AOPA President Craig Fuller; click here for that podcast.