What happened
On 6 February 2013, a serious incident involving three commercial aircraft occurred near Helsinki-Vantaa Airport during a period of snowy weather and varying visibility. At the time, the airport was utilizing segregated parallel runway operations, with runway 04L assigned for arrivals and 04R for departures.
Two aircraft, a Flybe Finland Embraer 190 (FCM746L) and a British Airways Airbus 320 (BAW79H), were performing instrument approaches to runway 04L. The arrival controller instructed the British Airways flight to execute a go-around because the separation between the two aircraft had fallen below the required minimum. Shortly thereafter, the crew of FCM746L also decided to abort their approach because the runway was still occupied by a preceding aircraft.
During the go-around maneuvers, the distance between the two arriving aircraft reached a minimum of 1.5 NM, with both flying at 3,000 feet. While the arrival controller directed the British Airways flight to turn left to increase separation, the tower controller issued a clearance to the Flybe flight to maintain the runway heading. This instruction placed the FCM746L almost directly above the approach path of runway 04L.
Simultaneously, a Scandinavian Airlines Boeing 717 (SAS717) departed from the parallel runway 04R. The tower controller's clearance to the Flybe aircraft caused a second serious conflict, as the FCM746L flew in close proximity to the departing SAS717. For approximately one minute and ten seconds, the two aircraft flew in the same direction with a separation of only 0.9 NM. During this time, the SAS717 climbed through the altitude maintained by the FCM746L, resulting in a significant breach of both lateral and vertical separation minima.
The investigation
The investigation examined the actions of the arrival and tower air traffic controllers, the coordination between different control positions, and the functionality of the airport's safety systems. Investigators reviewed radar recordings, which confirmed that the Short Term Conflict Alert (STCA) system had triggered warnings for the controllers. The investigation also looked into the procedures for managing aborted approaches and the criteria for maintaining independent parallel runway operations.
Findings
The failure of air traffic controllers to adequately react to STCA warnings was a critical factor in the near-collision. The investigation established that the primary cause of the conflict between the British Airways and Flybe flights was the clearance issued to the British Airways aircraft, which left the Flybe flight with insufficient airspace to execute a standard missed approach procedure. The conflict between the Flybe and Scandinavian Airlines flights was caused by the tower controller's instruction to the Flybe aircraft to follow the runway heading, which placed it too close to the departing aircraft on the adjacent runway.
Contributing factors included delayed decision-making by the arrival controller during an atypical traffic situation, a failure by both arrival and tower controllers to prioritize tasks effectively, and poor coordination between the different air traffic control workstations. Additionally, the investigation noted that the target spacing of five NM for arriving traffic was not being maintained.