Swiss probe serious airprox between Tu-154 and C-130

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Investigators have opened an inquiry after a serious airprox incident involving a Kazakh Tupolev Tu-154 and an Algerian Lockheed C-130 Hercules in Swiss-controlled French airspace.

Swiss accident investigation agency BFU says the incident occurred when a trainee controller at Geneva centre, after receiving a conflict warning, instructed the Tu-154 to arrest a previously-cleared climb from FL240 to FL260 – resulting in the aircraft’s levelling off at the C-130’s altitude of FL250.

An air traffic control instructor, who was monitoring the trainee, ordered the Tu-154 to execute an immediate rapid climb to FL300 but was unable to prevent the two aircraft closing to just 100ft vertically and 0.4nm horizontally.

At the time of the 8 February incident the Tu-154, operated by Berkut Air and registered UN-85173, had been flying northeast en route from Grenoble in France to the Kazakh city of Almaty.

The C-130 belonged to the Algerian Air Force and was registered 7T-WHB. It had departed Pardubice in the Czech Republic and was heading for the northern Algerian city of Boufarik.

No details have been disclosed regarding the number of occupants on board either aircraft. The incident occurred at 19:37, after sunset, near the KOGAS waypoint which lies to the east of Lake Annecy in France.

Although the short-term conflict alert warning sounded at the Geneva area centre it is unclear whether either aircraft’s crew received an alert from on-board collision-avoidance systems.

“The air traffic controller stopped the climb of the Tupolev at FL250,” says the BFU. “The instructor directly intervened over the trainee and gave the Tupolev the instruction to climb to FL300, and demanded the highest possible climb-rate from the aircraft.”

Swiss air navigation service Skyguide says: “After the incident Skyguide took necessary measures immediately, in accordance with procedures. The staff were replaced and attended to without delay and, where necessary, exempted from duty.”

It says that the radio communication and radar recordings have been preserved and handed to investigators. Skyguide stresses that the cause of the incident has yet to be determined, but adds: “The incident is already a subject of discussion in training and further education activities.”

The event has parallels with the fatal mid-air collision between a Russian-operated Tu-154 and a Boeing 757 freighter in Swiss-controlled German airspace, over Lake Constance, five years ago.

While the airprox between the Algerian and Kazakh aircraft occurred in French airspace, the country’s air accident agency Bureau d’Enquetes et d’Analyses has delegated investigation responsibility to the BFU, which expects to give further details on the incident at the end of March.