Statuts:	Enquête Officielle
Date:	31 MAR 1971
Heure:	06:33 PST
Type/Sous-type:	Boeing 720-047B
Compagnie:	Western Air Lines
Immatriculation:	N3166
Numéro de série:	19439/621
Année de Fabrication:	1966
Heures de vol:	11521
Cycles:	7011
Moteurs:	4 Pratt & Whitney JT3D-3B
Equipage:	victimes: 5 / à bord: 5
Passagers:	victimes: 0 / à bord: 0
Total:	victimes: 5 / à bord: 5
Dégats de l'appareil:	Perte Totale
Conséquences:	Written off (damaged beyond repair)
Lieu de l'accident:	Ontario International Airport, CA (ONT) (Etats-Unis d'Amérique)
Phase de vol:	En approche (APR)
Nature:	Entrainement
Aéroport de départ:	Los Angeles International Airport, CA (LAX/KLAX), Etats-Unis d'Amérique
Aéroport de destination:	Ontario International Airport, CA (ONT/KONT), Etats-Unis d'Amérique
Numéro de vol:	366

Détails:
Control was lost during a 3-engine missed ILS approach procedure and the aircraft crashed.
Failure of the aircraft rudder hydraulic actuator support fitting led to the loss of left rudder control. The loss of control situation was worsened by the degraded external visual clues (600 feet overcast; 1200m visibility in fog haze and smoke).

PROBABLE CAUSE: "The failure of the aircraft rudder hydraulic actuator support fitting. The failure of the fitting resulted in the inapparent loss of left rudder control which, under the conditions of the flight, precluded the pilots’ ability to maintain directional control during a simulated engine-out missed-approach. The existing weather conditions degraded external visual cues, thereby hampering rapid assessment of aircraft performance by the flight check captain."

Sources: