Investigation Summary
Approximately 35 minutes after departing Acapulco, the flight crew of the DC-9-32, named Tijuana, encountered a sudden cabin decompression while cruising at Flight Level 310 (31,000 feet). The captain declared an emergency and requested a return to Acapulco. During the subsequent emergency descent, the aircraft entered the mountainous terrain of the Sierra de Guerrero. The investigation focused on the crew's execution of the emergency descent profile. It was determined that the pilots did not adhere to the specific altitudes and procedures mandated for such an emergency in that region, resulting in a collision with terrain at 6,000 feet, roughly 65 kilometers east of Zihuatanejo.
Final Conclusions
The investigation concluded that the probable cause of the accident was the crew's failure to follow approved emergency procedures during the descent. This failure resulted in the aircraft descending below the minimum safe altitude for the mountainous region while attempting to return to the departure airport.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Cabin Pressurization System
The system failed during cruise, necessitating an immediate emergency descent to an altitude where occupants could breathe without supplemental oxygen.
Emergency Descent Procedure
A standardized maneuver used by pilots to rapidly descend to a safe altitude (usually 10,000 feet or the Minimum Sector Altitude) following depressurization.
Interesting Facts
- 01The aircraft was a McDonnell Douglas DC-9-32 delivered to Aeroméxico in 1974 (MSN 47622/753).
- 02The crash site was located approximately 65 kilometers east of Zihuatanejo in the Sierra de Guerrero mountains.
- 03All 18 occupants, consisting of 12 passengers and 6 crew members, perished in the accident.
- 04The aircraft was named 'Tijuana' and was powered by Pratt & Whitney JT8D-17 engines.
Safety Actions & Advisories
Adherence to Minimum Sector Altitudes (MSA)
Source ↗The accident highlighted the critical necessity for flight crews to maintain awareness of Minimum Sector Altitudes (MSA) even during emergency descents. While rapid descent is required for depressurization, pilots must level off at the higher of 10,000 feet or the MSA to avoid Controlled Flight Into Terrain (CFIT) in mountainous regions.