What happened
On May 11, 2016, at 07:34 UTC, a Boeing 777, registration F-GZNT, was being towed through taxiway R at Paris Charles de Gaulle Airport under Low Visibility Procedures (LVP). The aircraft was being moved by a tug crew consisting of a driver and a cockpit communicator (convoyeur).
At the time, an Airbus A320, registration F-GKXJ, was stationary at a holding point on the RT1 taxiway branch. Due to low visibility, ground controllers were relying on surface movement radar to manage traffic. Because the radar precision was insufficient to determine if the towed Boeing 777 could safely pass behind the stationary Airbus A320, the controller initially instructed the F-GZNT crew to maintain their position.
Two minutes later, the controller asked if the F-GZNT could proceed behind the F-GKXJ. The tug driver, intending to clear the taxiway, began moving the aircraft forward and slightly to the right. During this maneuver, the left wingtip of the Boeing 777 struck the vertical stabilizer and rudder of the Airbus A320. The collision resulted in damage to the vertical stabilizer and rudder of the F-GKXJ.
The investigation
The BEA investigation examined radar data, air traffic control (ATC) recordings, and interviews with the flight crews, towing agents, and controllers. The investigation noted that horizontal visibility was approximately 190 meters, with a runway visual range of 400 meters.
Investigators found that the tug driver's training did not include specific instruction on evaluating wingtip clearance distances from the tractor or the cockpit. Furthermore, the investigation highlighted that for "heavy" aircraft like the Boeing 777, the wingtips are not easily visible from the cockpit unless a window is opened. The investigation also noted that the Cockpit Voice Recorder (CVR) on the F-GZNT was not active, as standard procedures for towing did not require manual activation prior to engine start.
Findings
- The controller's request to proceed, following an initial instruction to hold position, led the tug driver to believe the aircraft was obstructing traffic, prompting the decision to move.
- The lack of visual clearance verification was a primary factor, as the driver relied solely on visual estimation in low-visibility conditions.
- The physical positioning of the aircraft at the holding points made it impossible for a Boeag 777 to follow the taxiway centerline behind the Airbus A320 without the wingtip encroaching on the stationary aircraft's space.
- The absence of ground anti-collision technology, such as camera systems, left the safety of the maneuver dependent entirely on the driver's visual perception.