United Airlines Flight 364
Boeing 757-222 · Incident during takeoff
From Portland International Airport (PDX) to Denver International Airport (DEN)
Event
- NTSB case
- SEA06IA105
- 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 757-222
- 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
- N506UA
- Operator
- United Airlines
- Onboard fatalities
- Unknown
- Route
- From Portland International Airport (PDX), Portland, ORTo Denver International Airport (DEN), Denver, CO
- 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
- Takeoff
- 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
- Miscellaneous/other
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Company maintenance personnel › Maintenance, alignment, inaccurate
- Miscellaneous eqpt/furnishings, slides › Unlatched
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
Post landing examination of the airplane by personnel from United Airlines and the Federal Aviation Administration revealed that the left off-wing escape slide had deployed, without inflating, and was observed hanging from the aircraft's fuselage. Further examination by United maintenance personnel revealed that the slide carrier tray assembly had rotated out to the open position. The off-wing slide compartment, door and operating latch mechanism were inspected by United maintenance personnel and no discrepancies were noted. Additional examination of the off-wing escape slide assembly by personnel from Boeing engineering revealed no evidence of mechanical malfunction with the system. Maintenance records indicated that on May 15, 2006, (four flights before the slide deployment) the off-wing escape slide pack was replaced in accordance with routine scheduled maintenance intervals for the assembly. The maintenance was completed, and inspected, by United Airlines personnel at a maintenance facility in Chicago, Illinois. A post incident Maintenance Investigation report submitted to the NTSB by United Airlines indicated that the inadvertent deployment of the off-wing slide assembly was the result of the carrier tray not being locked in the stowed position.
Probable cause
The inadvertent deployment of the off-wing escape slide due to the inadequate latching of the slide compartment door following access by maintenance personnel.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA06IA105
- Event ID
- 20060602X00675
- Case number
- SEA06IA105
- 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, damage. 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: 4fd6d6ab61f9c8b411ce4478afb76dd2858439806eb1fb46b9d588030e1e8494; retrieved 2026-09-18T14:53:17.108Z.
- The NTSB's operator name is blank for N506UA; the operator shown is the name the NTSB's other records give its FAA operator code, UALA.