What happened
On January 17, 2002, at 14:18 UTC, a separation violation occurred within the Helsinki Terminal Control Area (TMA). A Fokker F2 8 Mk 0070, operated by Malev Airlines as flight MAH742, was on a scheduled arrival from Budapest to Helsinki. Simultaneously, a Finnish Air Force Fokker F27-400M, call sign C21, was flying from Jyväskylä to Helsinki.
At the time of the incident, MAH742 was cleared for an RNAV transition to runway 15 and a descent to 2,000 feet, while C21 was being radar vectored on a heading of 230 degrees at 4,000 feet. The aircraft passed each other at a distance of approximately 1.85 nautical miles, violating the required 3-nautical-mile radar separation minima. The conflict was identified by the Traffic Alert and Collision Avoidance System (TCAS) on MAH742, which indicated the intersecting path of C21 at a similar altitude. Air traffic controllers subsequently issued corrective headings to both aircraft to restore separation.
The investigation
The investigation examined the RNAV transition procedures for Helsinki-Vantaa, the technical systems of the aircraft, and the operational performance of both the flight crew and air traffic controllers. Investigators reviewed radar data, flight plan information, and the implementation of area navigation (RNAV) methods at the time of the occurrence.
Findings
The primary cause of the separation violation was that MAH742 failed to follow the assigned Porvoo 1C RNAV transition route, specifically by failing to initiate a required anticipation turn before waypoint HK707. While a technical malfunction or crew error could not be entirely ruled out, the investigation identified several contributing factors:
- The pilot-in-command of MAH742 did not switch from lateral navigation (LNAV) to heading mode or request radar vectoring, despite observing that the transition route appeared as a rectangular shape on the cockpit navigation display without the necessary turn routing.
- The RNAV transition charts for Helsinki-Vantaa did not clearly indicate the specific P-RNAV requirements, which prevented the crew from recognizing that their B-RNAV equipment was insufficient for the assigned procedure.
- Air traffic controllers failed to monitor the planned vertical separation between the two aircraft effectively.
- The implementation and publication of the RNAV transition methods did not align with the EUROCONTROL guidelines in effect at the time.
Safety action
The investigators recommended that the Finnish Civil Aviation Administration (FCAA) improve its quality assurance mechanisms to better detect deficiencies in the design and implementation of navigation procedures. Additionally, it was recommended that the Hungarian Civil Aviation Authority require Malev Airlines to update its Flight Operations Manual regarding the handling of flight recorder data and to encourage crews to report FMS malfunctions during RNAV operations.