A passenger flying from Anchorage to Philadelphia was forced to stand for seven hours on a US Airway flight as a 400lb man sitting next to him made it impossible for him to get into his seat. 

According to Arthur Berkowitz, the obese man spilled over into his personal space and he could not move because the plane was full so he was forced to stand up.

Berkowitz also said that his co-passenger was very sorry about what had happened.

"The first thing he said to me was: 'I want to apologise - I'm your worst nightmare'," the Daily Mail quoted Berkowitz as saying.

Berkowitz's ordeal in July presented a safety risk because he could not use his seatbelt for take-off and landing.

"I didn't fly from Alaska to Philadelphia on Flight 901, I stood.

"His size required both armrests to be raised up and allowed for his body to cover half of my seat," he said.

The flight from Anchorage to Philadelphia is one of the longest non-stop U.S. domestic flights and Berkowitz thought he had a spare seat at first but before the door closed the airline asked a late-boarding passenger weighing 400lbs to sit down next to him in the last empty seat.

US Airways has also said sorry for the incident, which it described as "regrettable", and it offered the passenger a 200 dollars voucher in compensation.