2005 Geneva Airprox: AFR 563B and OHY 2451 (TC-OAE)

Incident Overview and Aircraft Details On June 30, 2005, at 17:18 UTC, a serious airprox occurred between two commercial aircraft in Class A airspace 71 nautical miles southwest of Geneva. The incident involved flight AFR 563B, an Embraer E145 with registration F-GRGL operated by Régional, and flight OHY 2451, an Airbus A321-231 with registration TC-OAE operated by Onur Air. Both flights were conducting IFR operations from Venice and Konya, respectively, toward Lyon St-Exupéry. ## Operational Context and Contributing Factors The incident occurred during a transition phase for Skyguide, which was unifying upper airspace control for Zurich and Geneva into a single center. Controllers were using new radar labels alongside traditional paper flight progress strips. The radar controller in the MA/MS sector, a Swiss national born in 1978, and the radar coordinator, born in 1951, were managing the sector. ## Sequence of Events At 17:11 UTC, OHY 2451 contacted the K2/L2 sector at FL300 and was assigned transponder code 5772. At 17:13 UTC, AFR 563B contacted the MA/MS sector at FL280 and was assigned code 5730. The E145's pre-correlated radar label, initially showing Milan-assigned code 0225, remained in pre-correlation until 17:13:38 UTC. The aircraft's Honeywell Primus RCZ-83X transponder entered standby mode because the pilot took more than five seconds to change the SSR code. This resulted in a complete loss of radar contact for 5 minutes and 12 seconds. At 17:16:12 UTC, OHY 2451 was cleared to descend to FL290 and transferred to the MA/MS sector, where it was subsequently cleared to FL280—the same level as AFR 563B. At 17:18 UTC, when AFR 563B requested to begin its descent, the controller could not locate the aircraft on radar. After the pilot confirmed transponder code 5730, the controller ordered a transponder reset. Once the transponder became effective, the E145's TCAS issued a climb resolution advisory, which the crew followed. ## Resolution and Closest Approach The E145 climbed to FL290 by 17:19:26 UTC, re-establishing separation. Radar data indicated that OHY 2451 had reached FL280 when the conflict was detected. The closest approach occurred at a horizontal distance of 1.1 NM, with the E145 at FL284 and the A321 at FL280. The A321's TCAS issued a descend advisory, but the crew reported that the situation returned to normal before they could follow it. The STCA alarm activated on the controllers' screens when the E145's symbol reappeared, 11 seconds after the crew announced the TCAS climb.