A 64-year-old Indian admitted he sexually abused a woman seated next to him on board a Hong Kong-Newark flight last year.
Ramesh Advani of New Jersey pleaded guilty before US District judge Dennis Cavanaugh to an information charging him with abusive sexual contact.
Advani's sentencing is scheduled for August 1, 2011.
He faces a maximum penalty of three years in prison and a $250,000 fine.
According to documents filed, Advani was seated next to a woman during a May 2010 overnight Continental flight from Hong Kong to Newark.
While the victim fell asleep in her seat, Advani reached his hand under her blanket and sexually abused her, a Department of Justice statement said.
When the woman awoke, she realised what was happening and informed the flight's crew members.
The federal government has exclusive jurisdiction over all sexual abuse cases that occur in American airplanes over international waters, because such crimes are not within the jurisdiction of any state, the statement added.