Incident Overview
On 25 February 2016, an incident occurred in the Rhein UIR (EDUU) involving a Boeing 737-800 (registration SP-ENX) and a Dassault Falcon 2000 (registration F-WWGP). The incident was classified as an air proximity event triggered by the Airborne Collision Avoidance System (ACAS).
Sequence of Events
While cruising at Flight Level 370, approximately 40 nautical miles west of Berlin, the crew of the Boeing 737-800 observed a climbing aircraft symbol on their Navigation Display. After establishing visual contact with the conflicting aircraft, the ACAS generated a resolution advisory (RA) lasting several seconds. The captain assessed that the situation did not require immediate reaction or a change of flight level. Once the traffic advisory ceased, the crew reported the event to air traffic control.
Investigation Findings
The investigation, conducted by the operator of the Boeing 737-800, included analysis of flight recorder data and pilot statements. It was determined that the crew deviated from procedures by not executing the 'CLIMB' command issued by ACAS. The operator's training department interviewed the captain and confirmed that the crew was familiar with ACAS procedures for the B737. The pilots explained that they did not follow the RA because the Falcon 2000 was being visually monitored and, in the captain's judgment, did not pose a collision threat; this explanation was deemed insufficient.
Data provided by the German investigation authority indicated that the minimum vertical separation between the aircraft was not violated. Transcripts of communications between ATC and both crews showed that both flight crews notified ATC about the TCAS RA. The Falcon 2000 was climbing to its assigned FL430 with a high rate of climb.
Cause
The incident was attributed to the too high rate of climb of the Dassault Falcon 2000.
Preventive Actions
The training department of the Boeing 737-800 operator required the captain to prepare a presentation on ACAS principles and procedures. This presentation was placed in the operator's electronic library, and all pilots were instructed to review its content.
Safety Recommendations
No safety recommendations were issued.