At nearly seven hours, US Airways flight 901 is one of the longest domestic nonstop airline flights. And Arthur Berkowitz knows how long it takes to get from Anchorage to Philadelphia down to the minute. That’s because he says he had to stand for most of the flight when he returned to Philly last July. Why would anyone stand for that long? Because he says a morbidly obese passenger seated next to him was spilling into his personal space, making it impossibly to sit in his assigned seat, and the flight was completely full.