Investigation Summary
During the descent from FL350, the crew observed green, yellow, and isolated red cells on their weather radar. They attempted to navigate between two intense red cells, but the aircraft entered an area of torrential rain and heavy hail. At approximately 16,500 feet, both engines experienced a flameout while at flight-idle power. The crew started the APU to restore electrical and hydraulic power. While descending through 10,500 feet, they attempted to restart the engines. Although the engines ignited using the starters, they failed to accelerate to idle and instead experienced rapid Exhaust Gas Temperature (EGT) increases toward red-line limits. The pilots, realizing the engines were failing due to internal damage from the ingestion and overheating, shut them down to prevent a fire. Captain Carlos Dárdano initially prepared for a water ditching in the Gulf Intracoastal Waterway but, upon spotting a grass levee, executed a sideslip maneuver to line up for a ground landing. The aircraft came to rest safely on the levee, which was part of the NASA Michoud Assembly Facility.
Final Conclusions
The NTSB concluded the probable cause was a double engine flameout due to water ingestion resulting from an encounter with very heavy rain and hail. A contributing factor was the inadequate design of the engines and FAA water ingestion certification standards, which did not account for the extreme 'waterfall' rates possible in high-intensity thunderstorms. The investigation noted that it is more difficult to start an engine in heavy precipitation than to keep one running, and the restart attempts in these conditions led to the overtemperature damage of the turbine components.
Video Analysis
The Full Story Of TACA flight 110 — A detailed look at how TACA Flight 110 suffered a dual engine failure due to hail and water ingestion and the incredible dead-stick landing that followed.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Crew Experience
Captain
Had 11,000 hours as pilot in command. Captain Carlos Dárdano.
First Officer
First Officer Dionisio Lopez.
Systems & Failure Modes
CFM56-3B1 Turbofan Engines
The engines suffered flameouts because the volume of water and hail exceeded the combustion stability limits. Subsequent restart attempts caused turbine damage due to excessive EGT.
Weather Radar
The crew used onboard radar to navigate between storm cells, but the radar may have been affected by attenuation (radar shadow), masking the true intensity of the storm core.
Auxiliary Power Unit (APU)
The APU provided critical electrical and hydraulic power after the dual engine failure, allowing the crew to maintain control and attempt engine restarts.
Interesting Facts
- 01The aircraft was a brand new Boeing 737-300 with only 81 airframe hours at the time of the incident.
- 02Captain Carlos Dárdano had previously lost an eye to crossfire during the Salvadoran Civil War.
- 03The aircraft was repaired on the levee by changing the engines and was flown off a nearby NASA roadway on June 6, 1988.
- 04The same airframe continued in service for decades, eventually flying for Southwest Airlines until its retirement on December 2, 2016.
- 05The incident led to significant modifications of the CFM56 engine to improve hail and water shedding.
Safety Actions & Advisories
CFM56 Engine Modifications
CFM International modified the engine by adding a sensor to force continuous ignition under heavy rain/hail, redesigned the nose cone, and adjusted fan blade spacing to deflect hail from the core.
Water Ingestion Certification Standards
The FAA and engine manufacturers revised certification standards to reflect higher 'waterfall' rates encountered in severe thunderstorms.