A Hawaii woman says she was forced to hold her son on her lap for a three-hour United Airlines flight last week after the company sold his seat to a standby passenger.

Shirley Yamauchi, 42, purchased two tickets for nearly $1,000 each so she and Taizo, her 27-month-old son, could fly together from Hawaii to Boston, where she was attending a teacher conference. United Airlines policy requires passengers above the age of 2 to fly in their own seats.

Yamauchi told HuffPost she was sitting on the plane with her son after a five-hour layover in Houston when a man came to their row and showed his ticket, which had the same seat number as her sons. He said he was a standby passenger.

Yamauchi said she told a flight attendant about the issue after the man arrived, but was offered no help.

She shrugged, said the flight was full, Yamauchi told HuffPost. The whole transaction was very quick.