What happened
On February 2, 2006, at 16:10 UTC, a runway incursion occurred at Helsinki-Vantaa airport involving three aircraft. A Finnair MD11, operating flight FIN095 from Helsinki to Bangkok, was cleared for takeoff from runway 04R. At the same time, an Aero Airlines ATR72, flight EAY2230, had recently landed and was taxiing toward a holding position. The aircraft was following a Blue 1 Oy Saab 2000, registration OH-SAX, which had stopped at a previous holding point.
Due to the preceding Saab 2000 stopping, the ATR72 was forced to halt at taxiway ZD. Because the aircraft could not immediately establish contact with ground control due to frequency congestion, the ATR72 ended up positioned partially between the holding point marker and the edge of runway 04R. The tower controller, managing departures from runway 04R, issued the takeoff clearance to the MD11 without realizing the runway was not fully clear. As a result, the MD11 passed the ATR72 during its takeoff roll with less than the required separation minimum.
The investigation
The investigation examined the coordination between tower and ground controllers, the use of taxiway routes, and environmental factors. Investigators found that while the aircraft followed all received instructions, the ground frequency was heavily loaded, preventing the aircraft from receiving further taxi instructions. The investigation also noted that the controller's ability to verify the runway status via visual inspection was significantly compromised by darkness, snowfall, and a structural pillar in the control tower.
Findings
- The primary cause of the incident was that the tower controller issued a takeoff clearance without noticing that the runway was not clear according to required separation standards.
- The ground control frequency was congested, which prevented the Saab 2000 and ATR72 from receiving further instructions, forcing them to stop at taxiway ZD.
- The movement of the aircraft did not proceed as the tower controller had assumed.
- Visual observations were hindered by darkness, snowfall, and the physical structure of the control tower.