The market for new private jets is experiencing a lull, too. Sales numbers have fallen since their peak, before the financial crisis, and prices have plateaued in the last few years.
Part of this is explained by oversupply. A glut of corporate aircraft is flooding the market, pushing many manufacturers, such as Gulfstream and Bombardier, to cut back production. And when jet-owners upgrade to new models they flog their old wings. This depresses second-hand prices further, as Oliver Stone of Colibri Aircraft told the Financial Times.
Despite an economic recovery in America, demand for private jets has remained weak. And sales in emerging markets dropped off after commodity prices collapsed in 2014. 
Corporate belt-tightening has dampened demand further. Tesco, a supermarket, sold or returned its five planes in 2014 and 2015. In September GE announced that it would sell its corporate fleet. It hopes to save money by making executives travel on charter or commercial flights. That is just as well, because it will not get much for its planes on the second-hand market.