What happened
On February 26, 2020, at 09:06, a Bombardier DHC-8-400, registration TF-FXA, was performing a scheduled flight from Reykjavík to Egilsstaðir. The weather at Egilsstaðir Airport (BIEG) was severe, characterized by heavy snow, blowing snow, and very low visibility.
Prior to the arrival of flight FXI326, airport service personnel were conducting snow removal and runway friction testing. A sand spreader vehicle was deployed to distribute sand on the runway to improve braking conditions following the snow removal operations.
During the approach, the driver of the sand spreader left the apron to refill the vehicle's sand supply. The driver entered the runway via taxiway Bravo without requesting or receiving authorization from the air traffic controller (AFIS). As the aircraft was on short final, the air traffic controller noticed the vehicle on the runway and issued an urgent warning on the vehicle frequency, but the warning was not heard by the driver. The aircraft passed over the sand spreader, maintaining a minimum distance of approximately 10 meters from the vehicle.
The investigation
The RNSA investigation focused on the communication breakdown between the airport service personnel and the air traffic controller. The investigation examined radio logs on both the air traffic frequency (119.4 MHz) and the vehicle frequency (168.6 MHz).
Investigators found that while the air traffic controller attempted to warn the vehicle, the driver did not hear the transmission. The investigation also looked into the operational procedures for the sand spreader, noting that the vehicle's access to the sand storage area required driving across the runway area. Furthermore, the investigation identified a technical issue where the vehicle's radio would occasionally switch to an incorrect channel (Channel 1 instead of Channel 2) despite being set to the correct frequency.
Findings
- The primary cause of the incident was a communication failure involving the sand spreader driver's inability to monitor the 168.6 MHz vehicle frequency effectively.
- The driver entered the runway without obtaining the required authorization from the air traffic controller.
- The driver's radio was prone to switching to the wrong channel, preventing the reception of the controller's warning.
- The necessity of driving across the runway to access the sand storage area created a high-risk operational requirement.
- The driver was focused on refilling the sand supply and did not realize the aircraft was on final approach until the aircraft was nearly overhead.