Incident Overview

Date: Saturday 18 January 1969
Aircraft Type: Boeing 727-22C
Owner/operator: United Airlines
Registration Number: N7434U
Location: 20 km W off Los Angeles, CA [Santa Monica Bay] – ÿ United States of America
Phase of Flight: Take off
Status: Destroyed, written off
Casualties: Fatalities: 38 / Occupants: 38
Component Affected: The Boeing 727-22C aircraft, specifically the electrical system, including the standby electrical system, which was responsible for powering the aircraft’s instruments and lights.The Boeing 727-22C aircraft, specifically the electrical system, including the standby electrical system, which was responsible for powering the aircraft’s instruments and lights.
Investigating Agency: NTSBNTSB
Category: Accident
On January 15, 1969, a United Airlines Boeing 727-22C flight, N7434U, carrying six crew members and three22 passengers, impacted Santa Monica Bay, California, resulting in a fatal accident. The aircraft was destroyed, and all passengers and crew were fatally injured. The flight was scheduled to depart Los Angeles to Denver and Milwaukee, and experienced a significant delay due to inclement weather and loading problems. The flight commenced takeoff from gate 24 at 18:17, and the sound of an engine fire warning bell was detected at 18:07. Following the loss of the no. 1 engine, electrical power was lost, and the standby electrical system failed. The aircraft descended until it struck the sea, with the ocean depth at approximately 950 feet. The probable cause was a night, instrument departure where all attitude instruments were disabled by loss of electrical power, leading to a loss of attitude orientation.On January 15, 1969, a United Airlines Boeing 727-22C flight, N7434U, carrying six crew members and three22 passengers, impacted Santa Monica Bay, California, resulting in a fatal accident. The aircraft was destroyed, and all passengers and crew were fatally injured. The flight was scheduled to depart Los Angeles to Denver and Milwaukee, and experienced a significant delay due to inclement weather and loading problems. The flight commenced takeoff from gate 24 at 18:17, and the sound of an engine fire warning bell was detected at 18:07. Following the loss of the no. 1 engine, electrical power was lost, and the standby electrical system failed. The aircraft descended until it struck the sea, with the ocean depth at approximately 950 feet. The probable cause was a night, instrument departure where all attitude instruments were disabled by loss of electrical power, leading to a loss of attitude orientation.

Description

United Airlines flight 266, a Boeing 727-22C impacted Santa Monica Bay approximately 11.3 miles west of the Los Angeles International Airport, California, USA. The aircraft was destroyed and the six crewmembers and 32 passengers on board were all fatally injured. The aircraft, N7434U, performed a scheduled service from Los Angeles to Denver, Colorado and Milwaukee, Wisconsin. It had been operating since January 15, 1969, with the no. 3 generator inoperative. This was allowed because according to the Minimum Equipment List, the aircraft is airworthy with only two generators operable provided certain procedures are followed and electrical loads are monitored during flight. Flight 266 was scheduled to depart the gate at 17:55, but was delayed until 18:07 because of the inclement weather and loading problems. The flight commenced its takeoff roll on runway 24 at approximately 18:17. At 18:18:30 the sound of an engine fire warning bell was heard in the cockpit. The crew reported a no. 1 engine fire warning and stated that they wanted to return to the airport. Shortly after shutdown of the no. 1 engine, electrical power from the remaining generator (no. 2) was lost. Following loss of all generator power, the standby electrical system either was not activated or failed to function. Electrical power at a voltage level of approximately 50 volts was restored approximately a minute and a half after loss of the no. 2 generator. The duration of this power restoration was just 9 to 15 seconds. The Boeing descended until it struck the sea. The ocean depth at this point was approximately 950 feet. PROBABLE CAUSE: “The loss of attitude orientation during a night, instrument departure in which all attitude instruments were disabled by loss of electrical power. The Board has been unable to determine (a) why all generator power was lost or (b) why the standby electrical power system either was not activated or failed to function.”

Primary Cause

Loss of attitude orientation during a night, instrument departure, resulting in a loss of electrical power and subsequent failure of the standby electrical system.Loss of attitude orientation during a night, instrument departure, resulting in a loss of electrical power and subsequent failure of the standby electrical system.

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