"This isn't my company's aircraft, so let me present one of ours to you - a very beautiful one," Dou said, motioning to a red helicopter glittering in the sunshine a short distance away. Feeling that I'd done enough flying for one day, I declined his offer, but my fellow passengers were eager to enjoy another trip.

He Jixiao, a junior gardening student at Tianjin Agricultural University who looked quite angelic in her white dress, was certainly excited by the second flight. As she climbed out of the machine, she announced: "The red helicopter has better power and performance. Mr Dou just made it tilt at a crazy angle. It was great."

As Dou led us into his office, home to a large number of model aircraft, he noticed two high school students chatting and smoking in the air-conditioned space. "Out! How dare you smoke, you brats!" he said, signaling that they should leave immediately.

"They are students from Beijing No 56 Middle Students. They're learning to fly here," he said, as the boys exited the building.

Xie Zichen was among 10 students from the school currently training at the airfield. He started three years ago and has decided to specialize in flying helicopters. "I come here every winter and summer vacation. It's cool to fly, although I am not allowed to fly solo yet," the 17-year-old said, adding that he has always been interested in aviation and is considering making a career in the industry. In total, 40 students from the high school have trained with Dou.

"You see, it's the summer vacation, so I've asked some executives to go home to make room for these children," he said.

Dou and five staff members he sent to the US to train as pilots have taught about 60 students since they began offering flying courses in November. The cost of studying for a private pilot's license is at least 150,000 yuan and includes 40 flying hours, while training for a commercial pilot's license costs 800,000 yuan and the students have to spend at least 250 hours in the air. If everything goes smoothly, a PPL learner can pass the theory exam and flying test in one to two months.

Only 10 all-purpose aircraft are allowed to be in the air simultaneously, because only two employees are in charge of flight safety, while six others are charged with checking and repairing the aircraft.

"I have very high standards when I choose employees - they must be fully qualified and experienced," Dou said. He's one of a very small number of people in China qualified to train pilots to fly both helicopters and fixed-wing aircraft.