An American Airlines pilot died on Monday on a red-eye flight from Phoenix to Boston. The flight was diverted to Syracuse, New York, where the co-pilot landed the plane safely.

"Syracuse, American 550, medical emergency, captain is incapacitated, request handling for runway," the co-pilot can be heard saying on a recording of the radio transmission from the plane. There were 147 passengers, as well as a crew of five, aboard the Airbus A320.

American Airlines flight #550 arriving at Logan after pilot died, diverted to Syracuse. Phoenix to Boston #wbz pic.twitter.com/uEVcqQUfKP — Christina Hager (@HagerWBZ) October 5, 2015

The airline has not yet released any information about the pilot or cause of death, and did not specify if the pilot died during the flight or after the plane landed. A spokeswoman told Mashable that the focus is on the crew's family on what is a very sad day for the airline.

“American Airlines Flight 550 diverted to Syracuse Hancock International Airport (SYR) early this morning due to pilot illness," the airline said in a statement. "Unfortunately, our pilot passed away."

"We are incredibly saddened by this event, and we are focused on caring for our pilot’s family and colleagues."

American sent a replacement crew to Syracuse to get the customers to their final destination of Boston.

A passenger on the flight, Louise Anderson, told Syracuse.com that the crew calmly announced a medical emergency as well as the diversion over the loudspeaker. The specifics of the emergency were not revealed.

She said she had not paid particular attention to the pilot as she got on the plane.

"You don't really think about paying attention to everybody you come in contact with," Anderson said. "That's a little reminder."

She added that the emergency responders at Syracuse did not rush on the plane, which to her indicated the pilot had already died.

want to thank the crew from #us550 w me entire heart. they handled the situation today with grace. sending love to the pilot's family. — lulusaurus-rex (@lulakilla) October 5, 2015

This post was updated at 9:21 p.m. EST with the passenger's comments.