The Fire and Disaster Management Agency plans to develop a system to locate missing mountaineers using radio waves sent from their mobile phones, agency officials said.

To cope with the increasing number of mountaineering accidents resulting from a climbing boom among elderly and middle-aged people, the agency hopes to develop a system within the next few years to facilitate search operations by helicopter.

The system will pick up waves from cellphones even when the missing people are in zones where their mobile phones cannot be used to make calls, they said.

The agency will include 33 million yen in development costs for the system in a budgetary request for the next fiscal year, which starts in April. The request will be made by the end of this month.

Helicopters involved in search operations will carry antennas to detect cellphone stations and the direction from which mobile phone radio waves are coming.

Helicopters will try to detect waves sent by climbers from their mobile phones in response to waves from cellphone stations.

When the system detects responding waves, the helicopters will be able to narrow down the area from which the waves are coming to pinpoint the missing people.

Even if the system picks up waves from several mobile phones, searchers will be able to distinguish missing climbers from other people through telephone number data that can be obtained from the radio waves.

The agency plans to conduct experiments on the system using cars in the next fiscal year and load the system into helicopters from fiscal 2003 for tests to prepare for practical application.

Agency officials said it will ask climbers to register their cellphone numbers when they start climbing and switch on their phones in case they get lost.