The Chinese Air Force has begun to use H-6 bombers to train flight crews, a move experts say indicates the People's Liberation Army is steadily strengthening its bomber force by putting newer versions into service and moving older ones to flight schools.

Starting in early April, students at the PLA Air Force Harbin Flight Academy have been using the H-6 for bomber training. In the past, they used other planes to simulate bomber flights, according to the PLA Air Force.

The change will substantially shorten the time required to train bomber crews and strongly boost the bomber force's development, the Air Force said.

Fu Qianshao, an aviation equipment expert with the PLA, said that the Air Force used the Y-7 turboprop transport plane to train its bomber crews after the antiquated H-5 training bomber was retired nine years ago.

"We had no alternative but to use the Y-7 because at that time all the H-6s were in service with bomber divisions, and it would be unaffordable to refit an H-6 into a trainer," he said. "Now the old-version H-6s have started to be refitted as trainers, which means the plane's newest models have joined the Air Force."

Flying the H-6 will enable flight students to familiarize themselves with the bomber and make them qualified airmen as soon as they graduate and join bomber divisions, Fu said.

Wang Ya'nan, deputy editor-in-chief of Aerospace Knowledge magazine, said the use of the old H-6s at the flight academy shows that the PLA is continuously developing new versions of aircraft.

"Next, the military will probably upgrade the plane's engines and improve the bomber's aerodynamic design. The development of advanced H-6 models will allow the PLA to gradually retire the plane's old versions, which will be transferred to flight academies," Wang said.

The H-6 bombers are based on the Soviet-era Tu-16 Badger, which was designed in the 1950s and retired by Russia in the early 1990s. The plane's latest model is the H-6K, which has a longer operational range and is capable of firing cruise missiles.

The Air Force has sent those bombers on long-distance drills far into the Pacific Ocean since last year.