Alaska Airlines Boeing 737-790 incident
Boeing 737-790 · Incident: airframe, component or system failure en route
From Los Angeles International Airport (LAX) to Malmö Sturup Airport (MMX)
Event
- NTSB case
- LAX07IA014
- 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 737-790
- Aircraft type
- Boeing 737
- 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
- N614AS
- Operator
- Alaska Airlines
- Onboard fatalities
- Unknown
- Route
- From Los Angeles International Airport (LAX), Los Angeles, CATo Malmö Sturup Airport (MMX), Mexico City
- 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
- En route · cruise
- 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
- Airframe, component or system failure
- 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
- Fluid, hydraulic › Leak
- Fuel system, pump › Failure
- Hydraulic system, line › Fatigue
- Hydraulic system, line › Fractured
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
During cruise flight, just after entry into foreign airspace, the flight crew was alerted to a System B hydraulic failure, and they decided to return to, and land in the United States (US). Upon re-entry to US airspace, the flight crew declared an emergency and requested to land at the departure airport. On final approach, about 5 minutes after selecting flaps to 15 and lowering the landing gear, the flight crew was alerted to the System A hydraulic quantity gage, that had dropped to 0 pounds per square inch (psi). At this point both System A LOW PRESSURE LIGHTS illuminated and the airplane went into the manual reversion mode. The flight crew indicated that the airplane was difficult to control; however, they landed uneventfully at the airport. Maintenance personnel for the airline, and the airplane manufacturer, inspected the hydraulic systems. They noted that the initiating event was a failed engine driven pump. The secondary event was a cracked hydraulic line that failed due to fatigue. A metallurgical examination revealed the fatigue fracture initiated at the toe of the welding root where they were able to locate a crack that had propagated through half the perimeter. The airframe manufacturer redesigned the affected tube, part number 272A4451-87, a titanium tube, with part number 272A4451-200, a stainless steel tube.
Probable cause
A complete failure and depressurization of both hydraulic systems due to two separate events: 1) the failure of a engine driven pump on the 'A' system, and 2) the fatigue fracture and failure of a hydraulic line on the 'B' system.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX07IA014
- Event ID
- 20061101X01595
- Case number
- LAX07IA014
- 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: 2d9b15479fa1d154ed1f9e16281f9981960186eb6bf339a481bd97a26a34b561; retrieved 2026-09-18T14:49:45.170Z.
- The NTSB's operator name is blank for N614AS; the operator shown is the name the NTSB's other records give its FAA operator code, ASAA.