What happened
On December 30, 2011, a Bombardier CRJ200, registration EK20018, was conducting a non-scheduled passenger flight from Yerevan to Nice. During the night approach, the crew was instructed to switch from the VORa runway 04L procedure to the VORb runway 22R procedure due to changing wind conditions.
During the initial phase of the new approach, the aircraft deviated from the prescribed track and descended below the minimum altitude of 1,500 ft. This triggered a Minimum Safe Altitude Warning (MSAW) that lasted for 41 seconds. Shortly after, an Area Proximity Warning (APW) activated as the aircraft continued to deviate from the approach axis. The aircraft's descent rate reached 1,700 ft/min, reaching an altitude as low as 550 ft.
While the crew attempted a second approach, they again struggled to intercept the required radial, leading to further trajectory deviations. The controller eventually transitioned the aircraft to a visual approach to ensure safety. The aircraft eventually landed on runway 22R without further incident.
The investigation
The BEA examined the flight path, the controller's actions, and the functionality of the airport's warning systems. The investigation noted that the controller was simultaneously managing a departing aircraft, which diverted his attention from the vertical aspect of the CRJ200's flight path.
Investigators also analyzed the performance of the MSAW and APW systems at Nice. They found that the MSAW system frequently generated unwanted alerts, leading controllers to lower the audible alarm volume. Additionally, physical obstructions, such as documentation covering the speakers, were noted in the control tower.
Findings
- The crew's inadequate execution of the approach was a primary factor, as their resources were likely overwhelmed by the complexity of the procedure and the sudden change in arrival configuration.
- The controller's delayed detection of the altitude deviation contributed to the event, as his attention was focused on horizontal separation and managing another aircraft.
- The MSAW system's effectiveness was compromised by a high rate of nuisance alerts, which led to the audible alarm being set at a very low volume, making it difficult to perceive during periods of high workload.