Airbus lifted the lid on one of the aircraft industry’s worst-kept secrets on Thursday, revealing the scale of average discounts in the cut-throat global jet market. For years, planemakers such as Airbus and U.S. rival Boeing have grabbed headlines by announcing orders at catalogue prices that are far above the real market value of jets. But on Thursday, Airbus issued new figures suggesting that the average aircraft discount is close to 50 percent. That is because the planemaker was forced to reveal the net value of its huge order backlog at market prices under new IFRS 15 accounting rules.