Serious incident Boeing 777-223ER N766AN,
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ASN Wikibase Occurrence # 314542
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Date:Thursday 20 January 2011
Time:22:35 LT
Type:Silhouette image of generic B772 model; specific model in this crash may look slightly different    
Boeing 777-223ER
Owner/operator:American Airlines
Registration: N766AN
MSN: 32880/445
Year of manufacture:2003
Fatalities:Fatalities: 0 / Occupants:
Aircraft damage: None
Category:Serious incident
Location:80 nm SE of New York, NY (Atlantic Ocean) -   Atlantic Ocean
Phase: En route
Nature:Passenger - Scheduled
Departure airport:New York-John F. Kennedy International Airport, NY (JFK/KJFK)
Destination airport:São Paulo-Guarulhos International Airport, SP (GRU/SBGR)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
A near-midair collision occurred between American Airlines flight, AA951 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.

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.

Accident investigation:
Investigating agency: NTSB
Report number: OPS11IA246
Status: Investigation completed
Duration: 1 year and 9 months
Download report: Final report



History of this aircraft

Other occurrences involving this aircraft
11 April 2011 N766AN American Airlines 0 ~194 nm east of RJAA non

Revision history:

02-Jun-2023 18:31 ASN Update Bot Added
04-Jun-2023 11:58 harro Updated

Corrections or additions? ... Edit this accident description

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