BEIJING - Xi Jinping, general secretary of the Communist Party of China (CPC) Central Committee, has extended his "condolence with deep feeling of grief" on the unexpected death of Luo Yang, the on-site director-in-chief of China's carrier-borne J-15 fighter jet research program.

In his instruction, which was made on Monday but publicized on Tuesday, Xi called Luo's death "a big loss to the Party as well as to the nation," and he also extended words of comfort to Luo's family.

Xi, also chairman of the CPC Central Military Commission, said Luo devoted himself to the country's aviation industry and made an extraordinary contribution to its development.

The Party and military leader urged all Party members and cadres to learn from Luo's qualities and treasured spirit. He asked relevant departments to take good care of Luo's family.

Luo, chairman and general manager of the Shenyang Aircraft Corp. (SAC), headed the manufacturing and production phase of the J-15 fighter jet. He had a heart attack onboard the carrier after the successful landing of the J-15 on Sunday, and later died in hospital at the age of 51, according to an obituary issued by the SAC.

Chinese people nationwide, including Luo's colleagues, acquaintances and netizens, have mourned his death.