Northwest Airlines Flight 1191
Boeing 727-257 · Incident: gear collapsed during landing
From Detroit Metropolitan Wayne County Airport (DTW) to Harry Reid International Airport (LAS)
Event
- NTSB case
- LAX95IA246
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Boeing 727-257
- Aircraft type
- Boeing 727
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N712RC
- Operator
- Northwest Airlines
- Onboard fatalities
- Unknown
- Route
- From Detroit Metropolitan Wayne County Airport (DTW), Detroit, MITo Harry Reid International Airport (LAS), NV
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 121: Air Carrier
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Landing · landing roll
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Gear collapsed
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Minor
Cause areas
- Company maintenance personnel › Maintenance, overhaul, inadequate
- Landing gear, main gear attachment › Fatigue
- Landing gear, main gear attachment › Stress corrosion
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
AFTER TOUCHDOWN THE CREW FELT THE AIRCRAFT LURCH TO THE RIGHT. AN INSPECTION REVEALED THAT THE RIGHT MAIN LANDING GEAR OUTER CYLINDER TRUNNION HAD SHEARED AT THE MAIN LANDING GEAR BEAM TRUNNION SUPPORT. THE OPERATOR REPORTED TWO SIMILAR PRIOR INCIDENTS. THE FAILED TRUNNION AND THE TWO FROM THE PRIOR OCCURRENCES WERE SENT TO BOEING FOR DETAILED METALLURGICAL ANALYSIS. ACCORDING TO THE LAB REPORT, ALL THREE TRUNNIONS FAILED AS A RESULT OF A FATIGUE FRACTURE AND STRESS CORROSION WHICH INITIATED IN THE BLENDOUT TRANSITION RADIUS BETWEEN THE MACHINED DOWN TRUNNION JOURNAL AND THE CYLINDER. THE RADIUS WAS FOUND TO BE BELOW THE SPECIFIED MINIMUM AND NICKEL PLATING EXTENDED INTO THE AREA IN EXCESS OF THE LENGTH PERMITTED BY THE OVERHAUL MANUAL. SEVERE THROUGH-THICKNESS CRACKING IN THE CHROME PLATING WAS ALSO FOUND IN ALL THREE TRUNNIONS. ACCORDING TO THE OPERATOR, BOEING 727 LANDING GEAR OVERHAUL REWORK IS PERFORMED IN-HOUSE.
Probable cause
A shear failure of the right main landing gear outer cylinder trunnion due to fatigue and stress corrosion, and the operator's inadequate and improper overhaul procedures.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX95IA246
- Event ID
- 20001207X03986
- Case number
- LAX95IA246
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 55b0efa71a8508af09ece6f46bd114d7914cb01698b010d230186a773b440276; retrieved 2026-09-18T17:59:33.798Z.