China is mourning the death of Luo Yang, who made major contributions to the development of the country's first carrier-based fighter jet.

Xi Jinping, general secretary of the Communist Party of China Central Committee, has extended his "condolence with a deep feeling of grief" at the unexpected death of Luo, chairman and general manager of the Shenyang Aircraft Corp and on-site director-in-chief of China's carrier-borne fighter jet program.

Xi called Luo's death "a big loss to the Party as well as the nation", and he extended words of comfort to Luo's family.

Xi said Luo devoted himself to the country's aviation industry and made an extraordinary contribution to its development.

Luo headed the development and production of the J-15 fighter jet. He died of a heart attack shortly after leaving China's aircraft carrier, the Liaoning, on Sunday. He was 51.

"Luo Yang, I know you were too exhausted these days," his wife, Wang Xili, said as she watched his body being sent to a funeral home. "I don't want to lose you. You were so tired and now you can sleep!"

Her words moved everyone present to tears.

Chu Xiaowen, Party chief of the Shenyang Aircraft Design Institute, where Luo worked for 20 years after graduation, recalled: "After Luo finished his work at the Zhuhai Airshow, he flew to Beijing for a business meeting.

Then he took a helicopter to the Liaoning aircraft carrier without having any rest.

"On the Liaoning, I noticed he was seriously fatigued, and I tried to persuade him to take at least a short break, but Luo refused and told me he had to catch up with the agenda."

Xie Genhua, Party chief of the Shenyang Aircraft Corp and a longtime colleague of Luo's, wrote in a memorial letter: "Now, return home, Luo.

Your wife and sister have come to Dalian to receive you. Leaders and your brothers-in-arms from the People's Liberation Army navy have come to the hospital to bid you farewell, and leaders and your friends at the Dalian Shipbuilding Industry carried your coffin to the hearse and they were shouting ‘Now you are going home, our brother!'"

Researchers, technicians and workers at the Shenyang Aircraft Corp have been flooding the mourning hall at the company to express their respects and grief.

"I don't know the words to express how deeply sad I am," the general manager of a subsidiary of the company who gave his name as Li said on Wednesday as he left the mourning hall.

"Without Luo's contribution, our company would not be what it is today."

Tian Feng, of the Shenyang Aircraft Corp labor union, said: "Luo was always very nice to us ordinary workers. Our incomes saw substantial increases because of his efforts.

"In our hearts, he has not died. I think the best way to commemorate him is to work harder for our country's aviation industry."

A 32-year-old employee at the company said: "I don't believe he has left us. The name Luo Yang will live as long as the Liaoning aircraft carrier, and we will never forget him."

The man was too grief-stricken to give his name.

Receptionists at the mourning hall said every day more than 1,000 people, from primary school students to an 88-year-old man, have come to say goodbye to Luo.

Bombardier, a Canadian aircraft manufacturer and partner of Luo's company, sent a representative to Shenyang to express its sorrow.

In Beihang University, China's top aeronautics and astronautics institute and where Luo studied high-altitude equipment from 1978 to 1982, professors who taught him said he was a model for all students.

"Luo once told me that being busy at work made him feel happy because ‘our nation had so many missions to accomplish'," said Wang Jun, a member of the Chinese Academy of Engineering who tutored Luo.

Li Min, the instructor of Luo's class, said Luo's accomplishments far exceeded all expectations and his selfless spirit inspired admiration and respect.

Luo had never boasted of his achievements, according to Li Zhaojian, who shared a dormitory with Luo during their time at the university.

"I didn't know anything about his success and achievements until I saw them on the Internet and the TV. He used to keep a low profile."

Huang Yuchen, a postgraduate from the School of Aeronautical Science and Engineering at Beihang University, said: "His story has been encouraging us. We selected the profession of aeronautics and we are determined to serve our motherland with our knowledge. We will follow Luo's path."

In commemoration and respect, the Liaoning sounded its siren on Tuesday morning as the crew lined up along the bows saluting Luo.

Contact the writers at [email protected], [email protected] and [email protected]

Yang Yao in Beijing contributed to this story.