Relatives of victims who died in the 1985 Japan Airlines jumbo jet crash on Sunday marked the 33rd anniversary of the world's deadliest single-aircraft accident that claimed the lives of 520 crew members and passengers.

As in past years, relatives climbed the steep mountain trail to the Boeing 747 crash site on Osutaka Ridge in Gunma Prefecture to mourn their loved ones lost in the disaster.

Kimiko Yoshida, 84, who lost her daughter in the accident, said,"She is always on my mind, but I feel like I can get close to her every time I come here on Aug. 12."

The relatives also prayed for aviation safety, just days after a rescue helicopter crashed in the mountains of the same prefecture, killing all nine people aboard.

On Aug. 12, 1985, Flight 123, en route from Tokyo's Haneda airport to Itami airport in Osaka with 524 passengers and crew aboard, crashed into the mountainous area, killing all but four aboard. A rupture in the plane's rear pressure bulkhead led to its vertical stabilizer being blown off, destroying its hydraulics and rendering it uncontrollable.

A government investigation commission in 1987 concluded that the accident was caused by faulty repairs conducted by Boeing Co., the aircraft's manufacturer, on the pressure bulkhead in 1978, with JAL failing to detect any problems in its maintenance checks.

Japanese police referred a total of 20 people, including Boeing and JAL employees, to prosecutors for their alleged negligence in 1988. However, none were ever indicted after Boeing refused to cooperate.

Among the dead in the accident, which occurred during the Bon summer holidays, was 43-year-old singer Kyu Sakamoto, who is known for his hit song "Sukiyaki," as well as many families, including children.