What happened
On July 3, 2017, an Avianca Airbus A320 (registration N742AV) was operating a non-passenger repositioning flight from Leticia to Cali, Colombia. While en route via airway UL655, the aircraft was cruising at FL380 when Bogotá Air Traffic Control (ATC) authorized a descent to FL190. This altitude was significantly below the Minimum Enroute Altitude (MEA) of FL250 established for that sector.
As the aircraft continued its descent, it passed through the mountainous terrain of the Cordillera Central. At approximately 03:25 local time, while 35 NM from the Cali VOR, the aircraft's altitude had dropped to approximately 13,200 feet, well below the required safety minimums. This triggered the Enhanced Ground Proximity Warning System (EGPWS) with "TERRAIN" and "PULL UP" alerts. The crew initiated an evasive maneuver, climbing to 14,900 feet before resuming the approach and landing safely at Cali International Airport without further incident.
The investigation
The GRIAA investigation focused on the breakdown in altitude separation and the crew's response to the warnings. Investigators examined the ATC instructions provided by Bogotá and Cali Approach, noting that the initial incorrect altitude assignment was ratified by Cali Approach without correction. The investigation also reviewed the aircraft's flight data, specifically looking at the crew's execution of emergency procedures and the operational environment, including the crew's recent flight schedules and the lack of a formal flight briefing for this infrequent route.
Findings
- Loss of situational awareness by the crew, who failed to verify the MEA and MORA for the sector and accepted ATC instructions without analyzing the altitude implications.
- Incorrect ATC authorization by Bogotá Control, which assigned a flight level below the established minimum, and by Cali Approach, which failed to identify the altitude inconsistency.
- Improper execution of emergency procedures, as the crew did not apply the required TOGA (Takeoff/Go-Around) power settings during the EGPWS activation.
- Accumulated fatigue of the commander, which likely impaired decision-making and operational analysis.
- Communication failures within the cockpit, specifically the lack of a flight briefing regarding the non-routine route and the failure to notify ATC of the EGPWS activation.
- Technical limitations at the Cali Approach station, where the audible Minimum Safe Altitude Warning (MSAW) was non-functional due to a database configuration error.