What happened
On 20 July 2013, a Boeing B-767-300, registration G-TCCA, operated by Thomas Cook Airlines Ltd., and a Piaggio P-180 “Avanti II”, registration D-IVIN, operated by AirGo Flugservice, were involved in a separation incident near point GALAT during departure from Palma de Mallorca Airport.
Both aircraft departed from runway 06R following the GALAT 2R standard instrument departure (SID). The Piaggio P-180 departed first, followed approximately four minutes later by the Boeing B-767-300. While both aircraft were climbing, the air traffic controller at the Palma Area Control Center (ACC) cleared the Boeing B-767-300 to climb to flight level 280, the same altitude previously authorized for the preceding Piaggio P-180.
As the Boeing B-767-300 climbed, its superior performance—specifically a higher ground speed and climb rate—caused it to rapidly close the gap with the slower turboprop. At 10:12 UTC, the crew of the Boeing B-7CL received a Traffic Advisory (TA) from their TCAS. Shortly after, the crew was instructed by ATC to turn right, and subsequently received a TCAS Descent Resolution Advisory (RA). The minimum vertical separation between the two aircraft dropped to 300 feet, with a minimum horizontal separation of 0.5 NM.
The investigation
The CIAIAC investigation examined radar data from the SACTA system, communications between the aircraft and the Palma ACC, and statements from the flight crews and air traffic controllers. The investigation analyzed the performance capabilities of both aircraft, noting that the Boeing B-767-300 reached ground speeds of approximately 370 kt, while the Piaggio P-180 maintained speeds between 210 and 220 kt.
Investigators also reviewed the operational configuration of the Palma ACC, specifically the DEO sector, which had combined the Departure and OXX sectors to manage workload. The investigation also looked into why the Short-Term Conflict Alert (STCA) function of the SACTA system was not enabled in this specific airspace.
Findings
- The Boeing B-767-300 had a significantly higher climb rate and ground speed than the preceding Piaggio P-180, leading to an excessive reduction in separation.
- The air traffic controller cleared the trailing aircraft to the same flight level as the lead aircraft without accounting for the performance disparity.
- The separation loss was detected late by ATC, necessitating evasive maneuvers and a TCAS resolution advisory.
- The STCA function in the Palma ACC was disabled to prevent nuisance alerts, removing a critical technological safety barrier.
- The combination of the Departure and OXX sectors increased the controller's workload and geographic focus, contributing to a momentary lapse in monitoring the closing distance between the two aircraft.