gmentation systems are the Wide Area Augmentation System (WAAS) from the U.S. Federal Aviation Administration (FAA) and the European Geostationary Navigation Overlay Service (EGNOS) from the GSA (on behalf of the European Commission). Both systems are heavily involved in enhancing navigation and safety for aircraft operations. These two systems, and others in various stages of deployment, are designed to be interoperable-so that aircraft equipped with one system can use another when in the airspace of another regional system. The only disadvantage to these GEO augmentation systems is that the satellites, being over the equator, are quite low to the horizon when the receiver is at high latitudes (toward the poles). This makes their use on the ground less than ideal because of obstruction to the line of sight from the satellites (something QZSS has addressed for Japan). However, to assist in those cases, the data is made available in other forms, allowing devices to access the same information from another source, such as the Internet. The signals are mostly fine at the altitudes used by commercial aircraft -anyway, there is only a limited amount of airports in the polar regions. WAAS is a system of three GEO satellites anchored over the equator above the Pacific Ocean, working with GPS data collected from 38 ground monitoring stations. WAAS is used to provide a GPS-enabled version of an instrument landing system across almost all North America as well as improve navigation across much of South America. EGNOS is a system of three GEO satellites stationed over the equator (above Africa), and 40 mon- itoring stations placed in more than 25 countries (not just in Europe). India's GPS-Aided GEO Augmented Navigation (GAGAN) is a system of three satellites stationed over the Indian subcontinent offering augmentation services for that region. GPS receivers with GAGAN capability use basically the same technology as WAAS. Japan also has a system based on GEO satellites (most recently MTSAT-2 or Himawari 7) and was known unt