New York (CNN) -- A near mid-air collision last month between a commercial airliner and two military planes just outside New York City is under investigation, the National Transportation Safety Board said Friday.
According to the NTSB, an American Airlines Boeing 777 left John F. Kennedy airport heading for Sao Paulo, Brazil, on January 20 when it encountered two U.S. Air Force C-17s, which were headed toward McGuire Air Force Base in New Jersey.
Radar data indicates the aircraft came within a mile of each other at their closest point, a statement from the NTSB said.
The near collision sent an electronic notification to the NTSB, the air traffic controllers, and the American Airlines crew, allowing them to avoid any contact between the aircraft.
"Every airline has to make sure such incidents don't happen," said Ed Martelle, a spokesman for American Airlines, who said he was unaware of the incident until he was contacted by CNN.
The incident is being investigated as "operational error," according to the NTSB.
Martelle declined to comment further on the incident due to the ongoing investigation by the NTSB.
CNN's Upinder Pathania contributed to this report.