The Airbus A320neo family is considered a global success in aviation, particularly with the introduction of new Airbus A321 variants. However, this very successful family has its own black sheep, the A319neo, which has not achieved the same level of popularity as its larger siblings. But why? Why is the Airbus A319neo widely regarded as a commercial failure? In an era when aircraft manufacturers chase ever-greater economies of scale and flexibility, the A319neo appears out of step. This aircraft has attracted fewer than a hundred orders, compared to thousands of A320 and A321s. Understanding this failure matters not only for the aircraft itself, but also for how airlines and manufacturers judge narrowbody programs in the post-pandemic, fuel-cost-sensitive world.