What happened
On March 27, 2018, an Airbus A318-112, registration N596EL, operating a scheduled passenger flight from Bogotá (SKBO) to Cali (SKCL), experienced a Ground Proximity Warning System (GPWS) activation while descending through mountainous terrain. The aircraft was executing the MANGA8 Standard Terminal Arrival Route (STAR) between the OREGA and MANGA intersections.
During the descent, the aircraft reached an altitude of 13,980 feet, which was below the established Minimum Enroute Altitude (MEA) of 17,000 feet. Upon the activation of the "Pull Up" warning, the crew performed an evasive maneuver, climbing to 20,640 feet. This climb exceeded the authorized flight level. The aircraft eventually resumed the arrival procedure and landed safely at Alfonso Bonilla Aragón Airport (SKCL) without further incident.
The investigation
The GRIAA investigation established that the flight was conducting an Initial Operational Training (EOI) for a First Officer acting as the Pilot Flying (PF), while the Captain acted as the Pilot Monitoring (PM). The investigation found that the PF programmed the Flight Management Guidance System (FMGS) with a descent limit of 14,000 feet, failing to observe the 17,000-foot MEA required by the MANGA8 procedure.
Regarding air traffic control, the Cali Approach radar system's Minimum Safe Altitude Warning (MSAW) had its audible alarm deactivated due to configuration issues. Although a visual altitude warning (AW) activated on the controller's screen when the aircraft breached the MEA, the controller did not notice the alert. Furthermore, the crew did not report the GPWS activation or the subsequent altitude deviation to the controller. Radar data also showed a brief loss of Mode C signal during the descent phase.
Findings
- Loss of situational awareness by the flight crew due to the incorrect programming of the descent altitude limit.
- Inadequate supervision by the Pilot Monitoring (the instructor) regarding the Pilot Flying, who was undergoing initial operational training.
- Communication breakdown within the cockpit, characterized by a lack of cross-checking the FMS programming and high levels of complacency.
- Failure in radar surveillance by the air traffic controller, who failed to detect the altitude deviation despite the active visual warning.
- Inoperative safety equipment at the control center, specifically the deactivated audible MSAW alarm.
- Lack of crew reporting, as the flight crew did not notify ATC of the terrain warning or the unauthorized climb.