Western Airlines Flight 366
Boeing 720 · Loss of control after mechanical failure of the rudder
From Los Angeles International Airport (LAX) to Ontario International Airport (ONT)
Event
- 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
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Unknown
- Event fatalities
- 5 · all aircraft and ground
- Ground fatalities
- 0
- Occupants
- Unknown
- Survivors
- 0
- InjuriesFatal: death within 30 days. Serious: over 48 hours in hospital within a week, most broken bones, severe bleeding, nerve or organ damage, or serious burns. Minor: anything less. Glossary
- 0 serious · 0 minor (NTSB)
- 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
- Instrument Meteorological Cond
Boeing 720
- Aircraft type
- Boeing 720
- 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
- N3166
- Operator
- Western Airlines
- Onboard fatalities
- Unknown
- Route
- From Los Angeles International Airport (LAX)To Ontario International Airport (ONT)
- 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
- Not recorded
- 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
- Approach · IFR missed approach
- Defining eventThe 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
- Uncontrolled collision with ground/water
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Miscellaneous acts, conditions › Material failure
- Systems › Rudder and rudder tab control system
Approximate · Coordinates from the Wikipedia article; not checked against an investigation report.
From the Wikipedia article
Western Airlines Flight 366 (flight number WAL366) was a training flight of Western Airlines from Los Angeles International Airport to Ontario International Airport in California, which was operated on 31 March 1971 with a Boeing 720-047B. While going around at the destination airport, the crew of the Boeing lost control of their aircraft, which resulted in the crash and the deaths of all five occupants.
Accident sequence
Flight 366 was conducted as a routine check flight to verify the proficiency of the pilots present. An ILS approach to runway 25 was flown with the aircraft, with engine No. 4 brought back to idle in order to simulate an engine failure. The responsible air traffic controller gave the captain clearance to land the aircraft or carry out a missed approach at his own discretion. About 100 feet above the runway, and thus at decision height, a simulated go-around with one engine failed was initiated. The aircraft climbed to 500 feet while rolling and yawing to the right. As the rolling and yawing motion continued, the aircraft plunged towards the ground on a southeasterly heading with its nose pointing almost vertically downwards. The aircraft disintegrated on impact, and all five occupants were killed.
Investigation and cause
Cause
The National Transportation Safety Board investigated the incident. The investigation found that the support fitting of the rudder's hydraulic actuator had failed, which led to the complete loss of control of the rudder shortly after the start of the go-around manoeuvre. The support fitting failed due to a combination of stress corrosion cracking and high tensile loading.
Translated into English with AI assistance from the German Wikipedia article “Western-Airlines-Flug 366” (revision 269022522, retrieved 2026-09-19) by its authors, under CC BY-SA 4.0. Extracted as plain text: references, tables, images and some sections are left out; the translation may contain errors, and long articles were cut to their first 700 words. Read the article
NTSB remarks
RUDDER HYDRAULIC ACTUATOR SUPPORT FITTING,STRESSCORROSION CRACKS.SIM 3-ENG MISSED APCH.
NTSB's remark from its 1962–1981 archive, as recorded (abbreviated, at most 98 characters): the archive has no narrative
Sources
German Wikipedia article: Western-Airlines-Flug 366
- Article
- Western-Airlines-Flug 366
- Translation
- Into English with AI assistance; names of linked operators and aircraft types from Wikidata. It may contain errors.
- Revision
- 269022522 · 2026-07-22 · retrieved 2026-09-19
- Wikidata
- Q97655703
- Licence
- Text CC BY-SA 4.0, by the article's authors; Wikidata CC0; town positions GeoNames (CC BY 4.0)
NTSB record
- Event ID
- 19710331P038560
- Case number
- Unknown
- Dataset
- historical-pre1982
- Source SHA-256
- abe1a933b4b73583d61684309f7f0610c281e3c1de3537c6471bf2a98ba6481d
Where each value comes from
- Record
- de Wikipedia article "Western-Airlines-Flug 366" (page 11275361, revision 269022522), translated into English with AI assistance; merged with NTSB case NTSB19710331P038560 (PRE1982 tblFirstHalf (one row per aircraft, grouped by date, place and time))
- Date
- NTSB record NTSB19710331P038560: PRE1982 DATE_OCCURRENCE
- Place and country
- Wikipedia infobox: site; country from NTSB record NTSB19710331P038560
- Map position
- Wikipedia: Wikipedia article coordinates
- Aircraft, operator and route
- NTSB record NTSB19710331P038560: PRE1982 REGIST_NO, ACFT_MAKE, ACFT_MODEL; gaps from Wikipedia infobox: aircraft type, registration, operator, origin and destination; route airports from the linked airport articles' Wikidata codes (OurAirports)
- Operation
- flight number in the article title
- Fatalities
- NTSB record NTSB19710331P038560: PRE1982 TOTAL_ABRD_FATAL of each aircraft, plus people on the ground and others outside the aircraft
- Ground fatalities
- NTSB record NTSB19710331P038560: events.inj_f_grnd
- Summary
- Wikipedia article lead
Source notes (4)
- One occurrence in two sources, merged: the Wikipedia article "Western Airlines Flight 366" and NTSB case NTSB19710331P038560, matched by the same aircraft registration and date. For this US event the NTSB's values are used where the two differ; each value names its source.
- From NTSB's 1962-1981 archive (PRE1982), which holds at most a short remark (98 characters, abbreviated) instead of a narrative; the accident type, phase of flight, causes and conditions are NTSB's codes, decoded as the archive defines them.
- Reviewed means this record passed the site's consistency check, not that it was checked against a narrative or report - there is none to check against.
- The operation category is mapped from the archive's operator and operation codes and has not been reviewed.