United Airlines Flight 426
Boeing 757-200 · Incident: in flight collision with object during initial climb
From Vancouver International Airport (YVR) to Chicago O'Hare International Airport (ORD)
Narrative check · The NTSB narrative appears to contradict this record's location. Values are shown as recorded, not corrected; compare with the narrative.
Event
- NTSB case
- SEA04IA175
- 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
- Unknown
- 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 757-200
- Aircraft type
- Boeing 757
- 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
- N526UA
- Operator
- United Airlines
- Onboard fatalities
- Unknown
- Route
- From Vancouver International Airport (YVR), Vancouver, BCTo Chicago O'Hare International Airport (ORD), Chicago, IL
- 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
- Initial climb
- 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
- In flight collision with object
- 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
- Flight control, slat › Delamination
- Object › Bird(s)
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The flight crew reported hearing a "grinding noise" during initial flap retraction after takeoff. A flight attendant subsequently notified the flight crew that there was a loud "hum and vibration" coming from the right wing. The captain instructed the flight attendant to scan the wing for any anomalies. The flight attendant notified the crew of damage to the wing's leading edge. The flight crew immediately diverted to Seattle, Washington, and performed a normal landing. A post event assessment of the slat by United Airline's engineering staff said "while there is no evidence of bird remains, it is our opinion that the damage was due to impact following takeoff, most likely bird, with subsequent damage caused by flight loads. The crew did not observe birds in the area. The characteristic of the damage does not lend itself to fatigue/delamination of the slat as cause." This incident was delegated to the NTSB by the Canadian TSB.
Probable cause
The slat was impacted by birds after takeoff and subsequently the slat delaminated due to flight loads.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA04IA175
- Event ID
- 20040930X01552
- Case number
- SEA04IA175
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (5)
- 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, coordinates. 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: 7ad5d4bba38e4536b576c522e15aaa718146b000aaa59ec7f940b8a1c92b3e4a; retrieved 2026-09-18T15:17:44.149Z.
- The NTSB's operator name is blank for N526UA; the operator shown is the name the NTSB records it doing business as.