What happened
On 7 January 2013, an Airbus A340-312, registration CS-TOC, operating as TAP-087 from Lisbon to Sao Paulo, and a Boeing 777-328-ER, registration F-GSQJ, operating as AFR-457 from Sao Paulo to Paris, experienced a loss of separation in the Canaries Oceanic Sector.
At approximately 02:18 UTC, the crew of the Airbus A3 .340-312 requested a climb from FL340 to FL360. Air traffic controllers at the Canaries Oceanic Control (GCCC OCE) initially denied the request due to existing traffic on the airway. However, after coordinating with the Sal ACC, the controller proceeded to clear the aircraft to climb. The climb began at 02:44 UTC.
Unbeknownst to the controllers, the Boeing 777-328-ER was traversing the same airway at FL350 in the opposite direction. Because the Boeing 777-328-ER had not yet established an ADS/CPDLC connection, it appeared only as a pseudotrack on the controller's display. At 02:48 UTC, as the Airbus A340-312 climbed through FL354, both aircraft's Traffic Alert and Collision Avoidance Systems (TCAS) triggered alerts. The systems issued a Traffic Advisory (TA) followed by Resolution Advisories (RA), instructing the Airbus A340-312 to climb and the Boeing 777-328-ER to descend. The crews followed the TCAS instructions, and the conflict was resolved without collision.
The investigation
The investigation examined the SACCAN system data, ATC communications, and the placement of flight progress strips. It was established that the Boeing 777-328-ER had not connected to the ADS/CPDLC system until it was already within the Canaries airspace, meaning its position was being estimated via a pseudotrack rather than real-time ADS data.
Furthermore, the investigation found that the flight progress strip for the Boeing 777-328-ER had been incorrectly placed on the controller's board, associated with a different airway and waypoint. This error, combined with the lack of an active ADS track, prevented the controllers from noticing the conflicting traffic during the climb authorization process.
Findings
- The primary cause of the incident was the incorrect placement of the flight progress strip for the Boeing 777-328-ER on the controller's board.
- The Airbus A340-312 was climbing into the path of the Boeing 777-328-ER because the controller was unaware of the latter's presence due to the strip error and the lack of an active ADS track.
- The Boeing 777-328-ER had failed to establish an ADS/CPDLC connection prior to entering the Canaries airspace, resulting in the use of a less accurate pseudotrack.
- There were discrepancies between the published flight level assignment tables in the AIP Spain and the actual practices used in Spanish airspace regarding northbound and southbound tracks.