911 SYSTEM BREAKS DOWN FOR 1-1/2 HOURS.

Byline: Daily News Staff and Wire Services

The center that runs the 911 emergency telephone system in Los Angeles broke down for nearly two hours Tuesday night, but calls were rerouted to local fire and police stations during the failure.

Police routed calls through a backup system that uses shortwave radio, but the city Fire Department apparently experienced a systemwide breakdown and used alternative local telephone numbers that were broadcast over local media.

Also, firefighters from the city's 102 stations patrolled their districts, said Brian Humphrey, a spokesman for the Los Angeles Fire Department.

San Fernando Valley police stations reported receiving hundreds of rerouted calls - mostly from people attempting to see if the system worked.

``It was just a deluge of people calling and hanging up and people calling to see if it works,'' said Lt. Gary Nanson of the LAPD's Devonshire Division.

City Fire Department helicopters were dispatched from Van Nuys Airport to fly over the region to make sure there were no fires or other obvious emergencies during the communications trouble, Humphrey said.

The Los Angeles County Sheriff's Department's 911 system never ceased operation, but people who heard about the city system problems burdened some sheriff's telephone lines, said Deputy Henry Garza.

Police Capt. Mike Downing, who commands the Central Dispatch Center, said calls were rerouted to the city's 18 local police divisions. The downtown dispatch center handles between 5,000 and 10,000 calls per day.

Pacific Bell technicians determined the problem was in a switch at the city's 911 dispatch center under City Hall East, said telephone company spokesman Steve Getzug.

``It's not a simple `On' or `Off' switch,'' Getzug said. ``It was in a number of circuits all meeting at the dispatch center.''

An investigation is under way to determine if the failure was in city-owned equipment or components owned and maintained by Pacific Bell, Getzug said.

The breakdown happened about 7 p.m., and the system was back in operation at 8:40 p.m., Humphrey said.

Tuesday night's breakdown followed a similar occurrence last month.

In the early hours of Nov. 10, hundreds of police officers lost normal radio communications with the city's 911 dispatchers for several hours due to a technical malfunction.

The malfunction caused a radio blackout between the 911 emergency center dispatchers working downtown near police headquarters and about 600 officers patrolling citywide during the overnight shift.

Preliminary investigations showed that breakdown was caused by a malfunction in a battery-charging system.

As on Nov. 10, police stations Tuesday night used shortwave radio to relay information to officers.

An estimated 180,000 calls went unanswered last year in Los Angeles, according to a recent city audit. The audit also showed 85 percent of the 3.6 million calls flooding the city's 911 system last year were not emergencies at all. Nationwide, that figure ranges from 50 percent to 90 percent.

Plans were already under way for two new dispatch centers, one downtown and another in the San Fernando Valley, that would decentralize the city's emergency dispatch system, to diminish the likelihood of future breakdowns.

Construction of one of the centers has been scheduled to begin in late 1998. Both centers are to be completed around 2002.