BY MARIKO SANCHANTA

TOKYO—Japan Airlines Corp. will shrink dramatically under a government-led restructuring plan, cutting significantly its work force, its routes, and the number of affiliated companies launched when the airline tried to diversify into a broad-based service firm.

Under the terms of its three-year restructuring plan, JAL is set to cut 15,700 employees, or about a third of its work force, and slash a total of 34 loss-making international and domestic routes, according to people familiar with the plan speaking Tuesday morning in Tokyo.

JAL was slated to file its petition for bankruptcy protection on Tuesday at 5 p.m. Tokyo time to ...