One carrier’s loss can be another’s gain. With the JetBlue-Spirit merger denied, both carriers are modifying their fleet plans, deferring deliveries on A320neos. That frees up additional delivery slots in the near term, which United Air Lines is poised to grab, according to the industry rumor mill and a report from BNN Bloomberg. Airbus is working with both other airlines and lessors to identify potential delivery slots for United in its complicated and supply-chain constrained skyline.United, the launch customer for the Boeing 737 MAX 10, removed the long-delayed aircraft from its fleet plan earlier this year. The MAX 10 will not be certified until 2025 at the earliest and may be subject to additional delays in the aftermath of the MAX 9 decompression accident in January. United has still not formally canceled its orders with Boeing and will likely wait to see how many A321neo aircraft can be made available from Airbus and the leasing community to fill the gap of 277 aircraft, already five years behind schedule. The most recent FAA report on Boeing’s quality system was critical, calling the process “inadequate and confusing.” This indicates the potential for further delays in certification and production ramp-ups for the 737 MAX. United is already a customer for the A321neo, with 180 firm orders before it restructures its fleet plan. The question is whether Airbus can source 277 aircraft to replace the Boeing order fully or only a portion of those aircraft would shift to the A321neo from the MAX 10.The Bottom LineWinning over United Airlines from Boeing to Airbus would be a significant win for the European-based plane maker and a tremendous loss for Boeing. When a major customer loses confidence in an aircraft program, it can have a cascading impact on future orders if other carriers concur with United’s conclusion. Fortunately for Boeing, Ryanair remains in the background and is willing to take up any positions canceled by United, as the divergence in opinion between the two carriers is quite extreme. Losing United would significantly impact Boeing’s reputation and the 737 MAX 10 program.The question is how many slots Airbus can provide and whether they can fill the gap to meet United’s need for additional lift. Finding 277 delivery slots is difficult with a nearly full skyline that stretches seven years.While we don’t expect Airbus to comprehensively cover all of the MAX 10 delivery positions immediately, they should be able to re-work their skylines with the JetBlue and Spirit deferrals and leasing company positions to offer United a significant number of aircraft. This underscores the need for a new aircraft at Boeing, as it cannot compete with its existing models. But a new aircraft will need to be efficient, with high quality and a focus on safety, which will be difficult in an environment that the FAA has deemed “inadequate and confusing.” The gap is widening, and the question is whether Boeing can afford to wait much longer before committing to a replacement for the MAX. Airbus' ability to meet United’s need for lift may be a critical factor in answering that question.