Airprox between Pegasus Airlines and Condor Berlin over Bern (D-AICB)

Incident Overview and Aircraft Details On 15 August 2003 at 20:08 UTC, an airprox occurred over Bern between Pegasus Airlines flight PGT992 and Condor Berlin flight CFG667. PGT992 was a Boeing 737 with registration TC-APR, operating from Geneva (LSGG) to Antalya (LTAI). CFG667 was an Airbus A320 with registration D-AICB, operating from Jerez (LEJR) to Stuttgart (EDDS). Both aircraft were flying in Class C reduced vertical separation minimum (RVSM) airspace. ## Operational Context and Sector Merger The incident occurred during the merger of sectors U1 and U2 at the Zurich Area Control Center (ACC). The sector merger was initiated due to low traffic volume. The Radar Planner (RP) of sector U1 moved to sector U2 and assumed the Radar Executive (RE) function for the combined sector. The RE of sector U1, who had previously issued a climb clearance to PGT992, was in the process of handing over control strips to the RP of sector U2. ## Sequence of Events At 20:05:31 UTC, PGT992 first called on the RE U1 frequency, reporting a climb to flight level 260. At 20:05:57 UTC, the controller cleared PGT992 to climb to flight level 300. At 20:06:43 UTC, CFG667 first called on the same frequency, reporting a descent to flight level 300. At 20:06:51 UTC, the new RE for the combined sector cleared CFG667 to fly flight level 300. At 20:07:40 UTC, a short-term conflict alert (STCA) appeared on the radar monitor. At this time, CFG667 reached flight level 300 in descent, while PGT992 was climbing through flight level 288 at approximately 2,000 ft/min. At 20:07:49 UTC, the controller instructed PGT992 to stop climbing at flight level 295. PGT992 received a TCAS traffic advisory (TA) followed by a resolution advisory (RA) to descend. The aircraft climbed to flight level 296 before descending to stabilize at flight level 295. At 20:08:13 UTC, the controller instructed CFG667 to turn right by 20 degrees. CFG667 reported it had initiated a TCAS climb. The aircraft climbed to flight level 313 before stabilizing at flight level 310 in accordance with a new ATC clearance. ## Findings The two aircraft approached to a vertical separation of 400 ft and a lateral separation of 1.4 NM. Both aircraft maintained continuous radio contact with the responsible controller. The conflict occurred during the sector merger and personnel handover. The controller who issued the climb clearance to PGT992 was not the same controller who resolved the conflict. The control strips for both flights were available in a timely manner and contained the necessary information. The workload in both sectors was low.