What happened
On March 22, 2018, a Piper PA-31-350 Chieftain, registration SE-FNE, operated by Jonair AB, was conducting an approach to Karleby-Jakobstad Airport (EFKK) in Finland. The flight, JON01, was arriving from Skellefteå Airport under challenging winter conditions involving heavy snowfall and light icing.
As the aircraft approached, runway maintenance was underway. The air traffic controller had authorized snow removal equipment, including brush sweepers, to operate on the runway. The crew of SE-FNE requested a landing despite the ongoing maintenance, noting that they did not wish to remain airborne longer due to the icing conditions and believed only a narrow strip of the runway needed to be cleared.
During the final stages of the approach, a critical breakdown in communication occurred. The air traffic controller attempted to instruct the pilot to abort the landing, but this instruction was not clearly received. Simultaneously, radio transmissions from a maintenance vehicle (the friction truck) were heard loudly through the controller's speakers, causing significant interference. The pilot, focused on verifying runway lighting settings, did not acknowledge the instruction to go around. Consequently, the aircraft continued its landing attempt while maintenance vehicles were still present on the runway surface.
The investigation
The investigation examined the sequence of events, the technical state of the communication systems, and the coordination between air traffic services and ground maintenance. Investigators analyzed radio recordings and interviewed the crew, the controller, and the maintenance personnel. The inquiry focused on why the instruction to abort the landing was not successfully communicated and why the maintenance vehicles had not been ordered to vacate the runway before the aircraft's arrival.
Findings
- The primary cause of the incident was a failure in radio communications caused by technical interference and overlapping transmissions.
- A transmission from a maintenance vehicle was routed into the air traffic frequency, creating loud noise that obscured the controller's voice.
- The air traffic controller was unable to track the aircraft's exact position during the final phase of the approach due to outdated equipment.
- The crew did not acknowledge the specific instruction to abort the landing, as they were preoccupied with requesting information regarding runway lighting.
- The maintenance crews were unaware that the aircraft intended to land immediately, as they had not received a formal clearance to vacate the runway.
Safety action
Following the incident, several actions were taken to prevent a recurrence:
- Air Navigation Services Finland Oy and Finavia Apb have worked to address the technical issue involving the incorrectly connected unit that caused the radio interference.
- Jonair AB updated its operational manuals to emphasize the importance of weather assessment and the captain's responsibility in verifying weather data before continuing an approach.
- The Swedish Transport Agency has implemented measures to improve crew resource management and radiotelephony standards.