What happened
On October 28, 2019, at 06:04, a BAE 125 series 800A, registration N812AM, experienced a runway excursion at the end of Runway 01 at Keflavik Airport (BIKF). The aircraft, operating a medical evacuation flight with 8 persons on board, landed at 06:03. After touchdown, the pilot proceeded to taxi toward taxiway N as instructed by Air Traffic Control.
As the aircraft approached the intersection of Runway 01 and taxiway N, the commander reported encountering black ice and noted difficulty decelerating. While the aircraft had slowed to taxi speed, it failed to complete the turn onto the taxiway. Instead, the aircraft skidded across the threshold lines for Runway 19 and exited the paved surface into the safety area. There were no injuries and no damage to the aircraft, though one crewmember slipped and fell on the icy pavement while exiting the plane.
The investigation
The RNSA investigation focused on the runway surface conditions and maintenance activities conducted by the airport operator, Isavia, during the night. The investigation established that heavy rain occurred between 03:30 and 04:30, which froze upon contact with the frozen ground, creating icy patches.
Maintenance records showed that deicing fluid had been applied to Runway 01/19 three times throughout the night in an attempt to maintain acceptable braking action. However, the investigation found that while the average braking coefficient for the runway appeared acceptable, a specific measurement taken at 05:55 revealed that the braking action at the far end of the runway (the Runway 19 threshold) had dropped to a coefficient of 0.22, which falls into the category of poor braking action according to ICAO Annex 14 standards.
Findings
- The primary cause of the excursion was poor runway conditions at the far end of the runway.
- Black ice had formed on the runway surface due to rain freezing on the frozen ground.
- While the average braking action for the runway was within acceptable limits, localized poor braking action existed at the runway threshold.
- The airport operator had been actively applying deicing fluid and sanding taxiways, but the rapid freezing of recent rainfall created localized hazards.