On 24 May 1988, TACA International Airlines flight 110 was descending towards New Orleans when it entered a severe thunderstorm cell. Hail and torrential rain extinguished both engines. The Boeing 737-300 glided down and landed on a grass levee beside the NASA Michoud Assembly Facility. All 45 people aboard were unharmed.
Why the engines quit
The aircraft flew into a cell containing extremely heavy precipitation and hail. Water and ice entering the engine core in that volume can disrupt combustion — effectively drowning the flame. Both CFM56 engines flamed out.
Attempts to restart produced a further problem: the engines relit but could not accelerate normally and overheated, and continued attempts risked destroying them. Captain Carlos Dardano shut them down deliberately rather than lose the electrical and hydraulic power that a windmilling engine still provides.
The decision
Dardano, who had one eye — he had lost the other years earlier in a shooting — flew the aircraft with First Officer Dionisio López and a check captain aboard. They were low, in weather, with no engines.
New Orleans International was too far. They identified an area of open ground near Michoud and set up for it. What they landed on was a grass levee, narrow and soft, beside a canal. Dardano touched down and stopped the aircraft without significant damage.
The aircraft flew out
This is the detail that makes TACA 110 unusual. The 737 was essentially undamaged. Boeing engineers assessed the site, the levee was strengthened and a temporary runway prepared, the engines were replaced, weight was stripped out, and three weeks later the aircraft was flown off the levee to a nearby airport.
It returned to service and flew for many more years.
What changed
The NTSB investigation looked at the engine's certification standard for water and hail ingestion. Existing test requirements did not reproduce the conditions inside an intense convective cell, particularly the combination of hail and water at high concentration with the engine at low power in a descent.
Certification standards for water and hail ingestion were revised, and engine control logic on the type was modified to reduce the likelihood of flameout in heavy precipitation and to improve relight behaviour.
Operationally the case reinforced storm avoidance training — the cell was visible on radar, and the flight's route into it was examined closely. The wider lesson taught from TACA 110 is not about the storm but about what the crew did once inside it: they stopped trying to restart engines that were destroying themselves, accepted they had a glider, and flew it to the best available surface.