Incident Overview
On Friday, July 11, 2014, at 23:54 local time, two Airbus A320 aircraft operated by Vueling experienced a loss of separation while approaching Barcelona Airport (LEBL). The aircraft, registration EC-IZD (flight VLG6107) and EC-LZZ (flight VLG8305), were approximately 13 nautical miles from runway 02 when they converged to a horizontal separation of 1.1 NM and a vertical separation of 200 ft. No injuries were reported among the 158 passengers and 6 crew on EC-IZD, nor among the 147 passengers and 6 crew on EC-LZZ. No damage to either aircraft occurred.
Sequence of Events
The incident unfolded during the approach phase. At about two minutes before the closest approach, the air traffic controller issued an instruction to EC-IZD. However, the crew of EC-IZD did not hear the instruction, and another aircraft mistakenly read back the instruction intended for EC-IZD. This error was not immediately detected by the controller or the crews of either aircraft.
Approximately one minute later, the controller recognized the developing conflict, with the aircraft still more than 6 NM apart. To resolve the conflict, the controller instructed both aircraft to execute evasive maneuvers. However, the instructions did not convey urgency or the reason for the maneuvers. Shortly thereafter, the Traffic Collision Avoidance System (TCAS) issued Resolution Advisories (RAs) to both aircraft. The combination of non-urgent ATC instructions and TCAS RAs likely contributed to a delay in the execution of the maneuvers, allowing the aircraft to come closer than intended.
Contributing Factors
The investigation identified three primary factors leading to the loss of separation:
- The crew of EC-IZD did not hear and therefore did not follow the ATC instruction.
- The instruction given to EC-IZD was read back by another aircraft.
- Neither ATC nor the flight crews initially detected these errors.
Additionally, the lack of urgency and missing reason in the evasive maneuver instructions, combined with the TCAS RAs, possibly delayed the crews' response, worsening the separation.
Aftermath
Both the air navigation service provider (ENAIRE) and the operator (Vueling) implemented corrective actions following the incident. Consequently, the investigation report does not contain any safety recommendations.