It is a good opportunity for Chinese financial leasing companies to get involved in the international market, with the Western economy still suffering, analysts said.

"The financial institutions in the West do not have enough money now and the powerful Chinese leasing companies can expand their international business," said Li Lei, a civil aviation analyst with China Minzu Securities Co Ltd.

The competition within the international aviation leasing market is fierce. Most of the Chinese leasing companies have only just entered the market, he said.

"The Chinese companies should make good use of the opportunities out there," he added.

It is an industry practice for airlines facing operational problems to sell their aircraft in order to revitalize other fixed assets.

"This transaction supports the management of our net debt position and our fleet alignment activities also in relation to our turnaround program Turbine," said Ulf Huttmeyer, chief financial officer of Air Berlin.

"Turbine" is a cost-cutting program that aims to slash about 900 jobs - 10 percent of its workforce - downsize its fleet and reduced unprofitable routes. The airline set a goal of the program of around 400 million euros ($533 million) in savings by the end of 2014.

Air Berlin also found another Chinese buyer. Ruili Airlines in Yunnan, which was given the green light to expand in May, signed a contract with the carrier to buy two Boeing 737-700s this year and two 737-800s next year.

Air Berlin's net loss for the second quarter of 2013 was 38 million euros, an improvement of almost two-thirds over the previous year's corresponding quarter, but its capacity decreased by 8.4 percent during the same period, according to the carrier's report.