I think the aircraft has only a tiny effect on profitability. In general, aircraft total cost of ownership and operations is proportional to size. There are som

I think the aircraft has only a tiny effect on profitability. In general, aircraft total cost of ownership and operations is proportional to size. There are some outliers, but the purchase price and/or leasing costs are negotiated up or down based off of perception of costs, so if there are any issues with aircraft costs they are short lived and go away after a while because those cost differences are eventually negotiated away. Similarly, any aircraft with lower than normal operational costs will have its price bid up until it breaks even with the cost levels of inferior aircraft (scarcity of production capacity for aircraft ensures that higher bidders get first dibs). The real issue is flight capacity utilization. Airline cost structures follow what accountants would call a step-fixed cost. In other words, the marginal cost per person is negligible until you fill the aircraft and then the marginal cost per person is the cost of a whole new flight. This also means that once you fill a plane past its break-even load factor, every additional seat sold is pure profit. The airline industry as a whole is operating on load factors between 82% and 84%, and it is net neutral in terms of profitability. That would lead me to believe that at current fuel prices (really the only source of variability in operational cost), that 83% load factors represent the zero-profit scenario. Now if Airline A can achieve 85% load factors, they will have a positive EBIT. If Airline B can acheive 87% load factors, they will roughly double the EBIT of Airline A. Some airlines make money. They do it using the same exact planes and technology as other airlines that do not make money. The difference is that they have higher load factors. They are better at selling seats.