Serious aviation incident on approach to Svolvær Airport Helle on 22 December 2022 involving a De Havilland Aircraft of Canada Limited DHC-8-103, LN-WIP, operated by Widerøe’s Flyveselskap AS

During an approach to Svolvær Airport Helle on 22 December 2022 with a De Havilland Aircraft DHC-8-103, LN-WIP, operated by Widerøe’s Flyveselskap AS, the crew had forgotten to set the local QNH.

The company had an altimeter setting procedure during which QNH was to be set. QNH was then to be verified as part of the approach checklist, pre-level procedure and radio height procedure. Using standard barometric pressure meant that the crew had an indicated altitude that was 700 ft higher than their actual altitude. When the aircraft was 3 NM from the runway threshold, the aircraft's terrain warning system (Enhanced Ground Proximity Warning System – EGPWS) gave a ‘Too tow terrain’ warning and the crew immediately aborted the approach and returned to Bodø. The investigation has shown that the procedures for setting and verifying the barometric altimeter applicable at the time of the incident were not sufficient to prevent the crew from forgetting to set the local QNH. When the crew forgot the first trigger for setting and checking QNH, the procedure and aids in the cockpit were not sufficient to identify the deviation and set the correct QNH. This incident also shows how ambiguity about whether a checklist should be carried out can result in an increased risk of undesirable incidents. It should be made clearer in Widerøe's operations manual and pilot training what should trigger the performance of a checklist.

The Norwegian Safety Investigation Authority recommends Widerøe’s Flyveselskap AS to develop improved procedures for setting and verifying the barometric altimeter (QNH) based on simplification and clarification of what should trigger setting and verification of QNH, and that such setting and verification should be carried out every time regardless of other aspects of the operational situation.

During an approach to Svolvær Airport Helle on 22 December 2022 with a De Havilland Aircraft DHC-8-103, LN-WIP, operated by Widerøe’s Flyveselskap AS, the crew had forgotten to set the local QNH.

The company's checklists and procedures for setting and checking QNH were not implemented in such a way that incorrect QNH was detected. To prevent incorrectly set QNH from leading to a catastrophic accident, the Norwegian Safety Investigation Authority like EASA, believes that an independent system is needed that monitors aircraft in Norwegian airspace and detects deviations between reported QNH and actual QNH. This requires that aircraft can send their pressure setting when interrogated by an Enhanced Surveillance System.

The Norwegian Safety Investigation Authority recommends Widerøe’s Flyveselskap AS, with its particularly challenging flight operations, to upgrade the transponders on their aircraft to enable them to transmit pressure settings and thus be part of a system for monitoring aircraft pressure settings (QNH) in Norwegian airspace.

During an approach to Svolvær Airport Helle on 22 December 2022 with a De Havilland Aircraft DHC-8-103, LN-WIP, operated by Widerøe’s Flyveselskap AS, the crew had forgotten to set the local QNH.

The company had an altimeter setting procedure during which QNH was to be set. QNH was then to be verified as part of the approach checklist, pre-level procedure and radio height procedure. Using standard pressure meant that the crew had an indicated altitude that was 700 ft higher than their actual altitude. When the aircraft was 3 NM from the runway threshold, the aircraft's terrain warning system (Enhanced Ground Proximity Warning System – EGPWS) gave a ‘Too low terrain’ warning and the crew immediately aborted the approach and returned to Bodø. This incident illustrates the weakness inherent in having procedural steps as the only preventive barriers to prevent controlled flight into terrain. The Norwegian Safety Investigation Authority agrees with the opinion expressed by EASA in SIB 2023-03 that in order to prevent an incorrectly set QNH from leading to a catastrophic accident, an independent system is needed to monitor aircraft in Norwegian airspace and identify deviations between reported QNH and actual QNH.

The Norwegian Safety Investigation Authority recommends the Norwegian Civil Aviation Authority conduct a new risk assessment to verify that the expected level of safety is maintained for cases with incorrectly set barometric altimeter. The risk assessment must be performed in close cooperation with aircraft operators and the air traffic services. The Civil Aviation Authority is then recommended to establish requirements for any risk-reducing measures in the short term and the use of technological solutions, in the long term, to address national risk challenges in line with the intention of EASA SIB 2023-03.