Information Bulletin No.92

Accurate Weather Forecasts, Courtesy of Commercial Airliners

March 29, 1996

Planning is underway for a new system for gathering weather information that will rely on passenger airplanes in flight and an artificial satellite. This next-generation flight control system, a Ministry of Transport project, will allow the Meteorological Agency to receive real-time meteorological data from aircraft via satellite that will assist in weather forecasting activities. In addition to further improving the accuracy of weather forecasting, the system is also expected to lead to safer flying.

Next-Generation Flight Control System
Flight control is currently based mainly on information supplied by radar. However, radar waves do not reach to distances of more than approximately 400 kilometers out to sea. Therefore when aircraft fly over the sea, data about the position of the aircraft is computed by a system mounted on the aircraft and transmitted to controllers via short-wave radio. Since information is only conveyed at once an hour, and short-wave radio is often inaccurate, adequate real-time control is impossible.
In contrast, the next-generation flight control system, scheduled to go into operation at the beginning of the twenty-first century, will employ a multipurpose geostationary satellite that the Ministry of Transport will newly launch and a Global Positioning System provided by polar-orbit satellite, already in use by the U.S. With this system, when aircraft fly in locations inaccessible to radar, such as over the sea, they will confirm their position using waves from the GPS of the aircraft, and then convey this information in real time to a flight control center via a geostationary satellite. In addition, weather information can also be dispatched to the Meteorological Agency.

Weather Information in Real Time
Passenger airliners already measure wind direction and speed, air temperatures and air pressure as they fly. However, because there is no data communications system, crew members simply use radio to communicate this data at fixed intervals, resulting in inadequate information. Estimates of atmospheric and other conditions over the sea out of reach of meteorological radar are made on the basis of photographs of cloud movements taken by weather satellites. It is this situation that prompted the investigation to establish a system to send real-time meteorological data from passenger airliners back to land.
When it is up and running, this system will vastly improve the accuracy of weather forecasts and the prediction of the paths of typhoons. In addition, when passenger aircraft hit turbulence, the instantaneous communication of this information back to land, whence it will be relayed to any following aircraft, is expected to generate the added benefit of safer flying.

(The above article, edited by Japan Echo Inc., is based on domestic Japanese news sources. It is offered for reference purposes and does not necessarily represent the policy or views of the Japanese Government.)