Introduction
On 24 May 2023, an Embraer ERJ 190-300, registration VH-IKJ, operated by Pionair Australia, descended below the minimum safe altitude during the Napier RNP 16 instrument approach at night. The aircraft conducted an orbit at 1,800 ft where the minimum safe altitude was 3,300 ft, then re-intercepted the final approach and landed at Napier Airport, New Zealand.
Findings
The Australian Transport Safety Bureau (ATSB) investigation found that the flight crew experienced a high workload during a critical phase of flight, and the aircraft became high on the vertical descent profile for the instrument approach. Perceived time pressures and the belief that visual approach criteria could be complied with influenced the crew's decision to conduct an orbit rather than a missed approach.
Prior to departure from Auckland, the flight was significantly delayed, and the crew were advised that Napier Airport would close if they did not depart within a short timeframe, creating a rushed preparation. The crew continued to feel rushed during the flight; the need to enter a holding pattern to burn extra fuel added to the perceived time pressure.
During the approach brief, icing was not identified as a potential threat, and the crew were unprepared to complete the Stall Protection Ice Speed checklist when the advisory message appeared. The first officer had difficulty locating the checklist in the electronic Quick Reference Handbook, leading to a high workload.
ADS-B data showed the aircraft became high on the vertical profile before joining the Napier RNP 16 procedure. The crew did not enter the published holding pattern at AROPA but instead continued descending to join the profile. At that time, the pilot monitoring was still completing the checklist and could not give full attention to monitoring the flight path.
The pilot flying used VNAV autopilot to descend, expecting it to capture the vertical glide path. However, being too high and underestimating the distance to run due to misinterpretation of a fly-by waypoint prevented the autopilot from capturing the glide path. The pilot flying attempted to capture it using flight path angle mode but was unsuccessful.
The captain decided to reduce workload by conducting an orbit rather than a missed approach, believing visual criteria could be met. Without further discussion, a left turn was commanded via autopilot, descending to 1,800 ft. This turn took the aircraft beyond the lateral tolerance of the intermediate approach segment and below the minimum safe altitude of 3,300 ft.
The flight crew reported that the E190-300 flight characteristics and autopilot system differ from other variants they were more experienced with. Their combined 89 hours of E190-300 experience likely contributed to the high workload.
Safety Actions
Pionair Australia took proactive safety actions, including:
- Replacing the aircraft's quick access recorder card; data capture and analysis are now ongoing.
- Developing a simulator exercise replicating the Napier event and managing a 2D approach when high on the profile; the exercise began on 6 June 2023 as part of the E190 recurrent simulator program.
- Issuing a notice to staff reiterating obligations to check the operational flight plan and receipt of all NOTAMs and weather forecasts.
- Including the decision-making events on the ground in Auckland, during flight, and approach to Napier in human factors and non-technical skills training.