What happened
On June 18, 2023, an accident occurred north of Arkösund involving an HA-BNS aircraft. The incident prompted an investigation by the Swedish Accident Investigation Authority (SHK), which identified several safety concerns regarding airport accessibility and air traffic control communication. The investigation focused on how Prior Permission Required (PPR) information is published and how the availability of air traffic services is communicated to pilots.
The investigation
The SHK examined the regulatory framework and communication standards used by airport operators and air traffic service providers. The investigation highlighted inconsistencies in how PPR is described in the Aeronautical Information Publication (AIP) and noted that the lack of a unified standard could impact flight safety. Furthermore, the SHK scrutinized the use of specific terminology by air traffic control, specifically the terms "open" and "closed," which were used during the accident.
Findings
One of the primary findings was a lack of standardized definitions regarding airport accessibility. The investigation established that the terms "open" and "closed" were not officially defined within the Swedish Transport Agency's regulations for radiotelephony and phraseology. This ambiguity created a significant risk of misunderstanding, as a pilot might incorrectly interpret a message to mean an airport is unavailable when it is actually accessible.
Safety action
The Swedish Transport Agency has implemented several measures to address the SHK's recommendations:
- To standardize PPR descriptions, the agency planned to collaborate with airport and air traffic service providers during industry events in early 2025.
- To assess the impact of PPR on safety, the agency initiated a survey of general aviation and airport operators during the first quarter of 2025 to analyze how accessibility restrictions affect flight operations.
- To resolve phraseology ambiguities, the agency is working on regulatory amendments to clarify that communications regarding "open" or "closed" status refer specifically to the operational hours of the air traffic service unit, rather than the physical accessibility of the aerodrome.