What happened
On 12 April 2019, at Strasbourg Entzheim airport, a serious incident occurred involving a Boeing 717-200, registered EI-EXB, and a Bombardier CRJ700, registered F-GRZG. The Volotea Boeing 717 was on an ILS approach to runway 05 when the local controller issued an immediate take-off clearance to the HOP! Bombardier CRJ7 and which was approaching the holding point.
While the controller provided traffic information regarding an aircraft on final approach, the specific aircraft type was not identified to the departing crew. As the Bombardier CRJ700 commenced its take-off run, the Boeing 717 continued its approach. However, the Boeing 717 crew, observing the departing aircraft still on the runway, initiated a missed approach at a low altitude of 240 ft.
Following the missed approach, the aircraft paths converged. The controller instructed the Bombardier CRJ700 to turn left and the Boeing 717 to turn right, but the Boeing 717 deviated to the left of the runway centerline. This maneuver brought the two aircraft into close proximity, triggering Traffic Collision Avoidance System (TCAS) Traffic Advisories (TA) and subsequently Resolution Advisories (RA), specifically a 'MAINTAIN CLIMB' for the departing aircraft and a 'DESCENT' for the aircraft on missed approach. The conflict was resolved once the crews complied with the TCAS instructions.
The investigation
The BEA examined flight data recorders, radio communications, and radar data. The investigation focused on the air traffic controller's decision-making, the lack of an approach fix for runway 05, and the communication gap caused by the use of both English and French during the sequence. The investigation also noted the absence of a radar image for the departing aircraft on the controller's screen until it reached approximately 1,600 ft.
Findings
- The local controller issued an immediate take-off clearance to prioritize runway optimization without sufficient regard for the risks of a potential low-level missed approach.
- The failure to specify the aircraft type in the traffic information prevented the departing crew from accurately assessing the separation risk.
- The absence of an approach fix for runway 05 at the time of the incident contributed to the difficulty in managing the arrival sequence.
- The use of different languages (English and French) between the controller and the two different crews hindered shared situational awareness.
- The Boeing 717's deviation from the runway centerline during the missed approach increased the horizontal closing rate between the two aircraft.