What happened
On December 17, 2005, at approximately 11:17 local time, a runway incursion occurred at Kuopio Airport involving two scheduled passenger flights. A Blue 1 Oy Saab 2000, registration OH-SAT, was taxiing toward runway 33 holding position F. Simultaneously, an Aero Airlines AS ATR 72-201, registration ES-KRE, was on an ILS approach to the same runway for landing.
During the taxi, the crew of OH-SAT received updated friction coefficient values indicating that the southern portion of the runway had become extremely slippery due to ice and fresh snow, with a friction value of only 0.16. Consequently, the crew paused their taxi near taxiway E to re-evaluate takeoff performance parameters and discuss departure techniques for slippery conditions. During this period of intense focus on performance calculations, the crew inadvertently taxied past holding position F and onto the active runway. The tower controller, having lost visual contact with the aircraft due to heavy snowfall, only realized the error when the OH-SAT crew radioed their readiness for takeoff at the runway threshold. The controller immediately ordered the approaching ES-KRE to perform a missed approach.
The investigation
The investigation examined the rapidly changing weather and runway conditions at the time of the incident. It was noted that heavy snowfall and localized fog—likely drifting from nearby artificial snowmaking activities—had significantly reduced visibility. The investigation also reviewed the cockpit procedures and the use of checklists. It was determined that the crew's attention was diverted by the increased workload of re-planning the takeoff under new surface conditions. Furthermore, the investigation found that the existing aircraft checklists did not sufficiently prompt the crew to verify their taxi clearance limits, and the crew had not utilized their operational flight plan as a memory aid for the taxi route.
Findings
- The primary cause of the incursion was the increased workload of the crew on OH-SAT resulting from the need to re-evaluate takeoff performance due to slippery runway conditions.
- This concentration on performance planning led to a failure to monitor taxi progress and radio communications, resulting in the aircraft crossing the hold short line.
- Rapidly changing weather and runway friction levels contributed to the incident.
- The aircraft's checklists did not provide adequate support for remembering taxi clearance boundaries.
Safety action
- The investigation commission recommended that the Civil Aviation Authority modify taxi procedures so that the initial taxi clearance for departing aircraft is always issued only up to the runway holding position, requiring a new clearance for any runway crossings.
- It was also recommended that aircraft checklist requirements be updated to include a specific check for runway taxi clearances.