US airline fleet aging updated through June 2025 |

Another month has passed, and US airlines have continued to take new deliveries. How has this impacted their fleets? Here's a public data visualization of the Big Four. Notes: The charts reflect our estimate of the fleets at the end of June 2025. The dashed vertical line is the average age of the fleet at that time. The menu for the aircraft type is helpful to demonstrate where the airline might need to focus its fleet refresh. A prime example of this is the regional aircraft. We opined on this issue earlier this week. Regional flying is in something of a critical phase. Regional flying is becoming more expensive. Orders for E-175s reflect choices made out of necessity. Airlines dislike the monopoly situation and are open to something that reflects state-of-the-art technology. The big four fleets reflect their consolidations with others. It's messy and is taking a long time to simplify. We try to address this in the notes below. While this analysis focuses on the Big Four, the sheer critical mass they represent is 76% of the industry's RPMs. These aliens drive the industry. American Airlines This fleet combines American, US Airways, and America West. After the pandemic, American simplified its fleet by retiring the A330s, 757s, and 767s. This may have been too much, as 787 deliveries never filled the capacity gap as the market recovered. Notice which aircraft are "over the line." The fleet needs to replace the A319s and A320s, which have a relatively high fuel burn per seat. These aircraft are legacy AmericaWest, so they are aging. The regional jets are on the wrong side of the economics. But this applies across the industry. The 777-200ER fleet is also aging. The challenge here is to deliver 787s to replace additional long-haul capacity cuts. On the left (better) side of the average line, we see the MAX 8s are coming slowly. Too slowly. The 737-800 and MAX 8 models are the core of the airline's single-aisle fleet. To compete on a fuel burn basis, American needs to accelerate the refresh. Delta Air Lines Here, the legacy is Delta and Northwest. Northwest was an Airbus airline, and Delta was a Boeing airline. You can see how that has changed, with Airbus now in favor. The fleet average age is the highest among the reporting airlines, which has negative implications for fuel burn. Not being part of the MAX delivery process has meant Delta continued to receive deliveries from Airbus. This worked exceptionally well for the A321, A330-900, and A350. A sizable chunk of the fleet is over the line. How Delta fixes this will be interesting. For example, Delta has ordered 45 A220-100s and currently has 37, with new deliveries being A220-300s. Has an upsize decision been made quietly? The 757s are set to be replaced by a combination of A321s and MAX 10s. The lack of the MAX 10 means more MRO costs, keeping the 757s in service. A330-900s will replace the 767s, but the process is taking too long. MRO impacts here, too. Finally, Delta faces the same challenges with regional jets. Converting some CRJ700s to CRJ550s is a temporary solution, and probably not the best choice. The CRJ550's fuel burn per seat is not competitive at all. Consider Delta to be highly focused on seeking a new solution, like MaeveJet. United Airlines Here, the fleet is legacy United and Continental. The latter was a Boeing exclusive customer. United operates a diverse fleet of aircraft, too many models to drive MRO efficiencies. The aircraft "over the line" reflects what we see at the previous airlines. Regional jets are mostly aging. Note, however, that there are several A319s, A320s, 737s, 757s, 767s, and 777-200s. The MAX 10 should replace the 757s. MAX 8s and 9s should replace the A319, A320, and 737NGs. But what about the 767s and 777-200s? The "natural" answer is 787. These delays impact United's fuel efficiency. United has announced ambitious new long-haul markets, and having the right aircraft is crucial to its success. Being Boeing-biased has brought network planning frustration. There is an old Airbus order for A350s. Not moving on this has probably been a mistake. United could have used these aircraft to good effect, with state-of-the-art fuel burn and low MRO costs. Southwest Airlines The legacy would have been the 717s from AirTran, but they were quickly sold off to Delta. Southwest embodied the philosophy of a simple fleet. That went out the window when upsizing to the -800NG started. Quick turnarounds within 45 minutes were no longer possible. Fortunately for Southwest, its switch to MAX 8s proved successful as loads increased after the pandemic. So it's not all bad news. The problem is that being dependent on Boeing has consequences. There is no MAX 7, and Southwest is "out of gauge." Its fleet went from 65% 140-seaters to 65% 175-seaters. This was great for routes that have the traffic to take up the capacity. The problem is that Southwest has many markets where 175 seats is too much. We see the airline now flying "red eyes" to increase flying hours and offset capacity. The simple model stopped working and attracted Elliott into its cosy world. It will be interesting to see how this plays out. Southwest was a market driver, but it is no longer.

US Flight Planner	Airbus vs Boeing
US Airline Schedule Performance	Daily Production & Deliveries

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