Japan Airlines said Monday it has reprimanded 15 more officials for their involvement in four separate mishaps.

The 15 include a pilot who attempted to take off without authorization from air traffic control at Hokkaido's New Chitose Airport in January, the nation's largest air carrier said. The pilot will be suspended from working for 10 days.

Another pilot and a copilot who misunderstood the control tower's instructions at Inchon International Airport in South Korea and moved their jet onto the runway were also given warnings, it said.

The two other mishaps were a March 16 incident in which cabin attendants failed to perform a safety procedure for emergency evacuation, and a case revealed in December in which a cargo plane was found to have had the wrong kind of wheel component for more than eight years.

An executive in charge of the cabin attendant division has returned a month's salary over the safety violation, while a senior official in charge of maintenance was admonished, JAL said.

Last Thursday, JAL submitted a set of preventative measures to Land, Infrastructure and Transport Minister Kazuo Kitagawa after the government ordered the airline in March to improve its operations.

The government has already reprimanded the JAL pilot in the Chitose incident and grounded him for 30 days.

The ministry also reprimanded the JAL pilot in the Inchon case.

The company has punished its top executives, including Chairman Isao Kaneko, who gave up his right to represent the company.