This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

(CNN) – United Airlines is investigating how a baggage handler became locked in the cargo hold of a plane and remained trapped during an hourlong flight.

In a statement, the airline said the man was found unharmed after United Airlines Flight 6060 landed at Washington Dulles International Airport on a New Year’s Day flight from Charlotte Douglas International Airport.

During the flight, the plane reached an altitude of 27,000 feet, according to CNN affiliate WBTV-TV in Charlotte, North Carolina.

Radio traffic revealed that workers initially treated the incident as a security issue, the CNN affiliate reported.

“We’re going to work it as a security incident until we can get some confirmation to who he is even though he’s in trade dress for a ramper in Charlotte. The flight crew doesn’t remember seeing him or anything like that,” radio traffic said, according to the TV station.

An airline representative told CNN that a vendor for United employs the baggage handler. The airline didn’t release the handler’s name.