There is no doubt that airlines rely on their widebodied aircraft for their long-haul operations, especially on high-capacity routes. Passengers look for comfortable cabins on long-haul flights and will often look closely at what the airlines are offering in terms of cabin quality. For the airlines, cost efficiency is crucial, and sustainability presents a huge challenge. Here, we will compare two of the largest airlines in the United States, United Airlines and Delta Air Lines, to determine which airline has the largest widebodied fleet.