The victims of the world's deadliest single-plane crash were mourned on Friday as their kin climbed a steep mountainside in Gunma Prefecture where Japan Airlines Flight 123 crashed 31 years ago.

In an annual ritual, they prayed at a monument to the 520 passengers and crew who died on Osutaka Ridge on Aug. 12, 1985, when their Boeing 747 slammed into the peak after a catastrophic decompression crippled the plane.

"We want to convey this accident to children and create a safety culture," said Kuniko Miyajima, 69, a representative of the families. Miyajima lost her 9-year-old son Ken in the accident and now conducts lectures on air safety.