Which aircraft is primarily used for domestic short-haul flights by American Airlines?

The Airbus A321 is primarily used by American Airlines for domestic short-haul flights due to its optimal combination of passenger capacity and range. This aircraft can comfortably accommodate a larger number of passengers compared to other short-haul aircraft. Its efficiency in terms of fuel consumption makes it a cost-effective option for shorter routes, allowing airlines to maximize profitability on these domestic flights. Furthermore, the A321 is capable of serving various airport pairs effectively, fitting well into American Airlines' route network, particularly for quick turnarounds and efficient operations on shorter routes.

While other aircraft like the Airbus A320 and Boeing 737 are also utilized for similar purposes, they may not have the same capacity or specific operational advantages that the A321 provides for short-haul travel. The Boeing 757 is generally used for slightly longer domestic routes or international flights and does not typically focus on the short-haul segment. Therefore, the A321's design and operational characteristics make it the most suitable choice for domestic short-haul flights in American Airlines' fleet.