Boeing 777 N766AN incident near 80 Se Of Jfk (Atlantic Ocean), New York

Probable cause

Incomplete and incorrect coordination between air traffic controllers that resulted in the 777 and the two C17s being cleared to maintain the same altitude. Contributing to the incident was the controllers’ non-adherence to established communications phraseology and incorrect data entry into the radar data blocks for each aircraft.

NTSB analysis

A near-midair collision occurred between a Boeing 777-200 and a flight of two US Air Force C-17s as the result of an operational error by controllers at the New York air route traffic control center (ZNY). The airplanes responded to traffic collision avoidance system (TCAS) advisories, and both controllers immediately provided traffic advisories and turned each aircraft to resolve the conflict. According to recorded radar data, the three airplanes passed within approximately 0 feet vertically and .38 miles laterally from each other.

The air traffic data controller, who was the coordinator between two radar controllers, told the controller working the 777 to stop the airplane at flight level (FL) 210. Following that coordination and while still on an open line with that controller, the data controller leaned toward the controller working the two-C17s and told him to stop his flight at FL220. The controller working the 777 overheard the portion of the communication where the data controller said to stop at FL220 and believed that the instruction was meant for the 777. Therefore, the controller instructed the 777 to climb to FL220, while at the same time the controller instructed the C17s to descend to FL220. Additionally, the investigation revealed that the radar data blocks for each of the airplanes displayed incorrect assigned altitude data. The data block for the 777 indicated that the airplane was cleared to climb to FL230 and the data block for the C17s indicated that the flights were cleared to descent to 10,000 feet. Both of these were incorrect: the radar data block for all involved airplanes should have reflected the assigned altitudes of FL220.

Text from the NTSB. Open the NTSB docket for OPS11IA246 for the full record.