United Airlines Flight 266
|Date||January 18, 1969|
|Summary||Mechanical failure leading to loss of electrical power|
|Site||Santa Monica Bay, California, USA|
|Aircraft type||Boeing 727-22C|
United Airlines Flight 266 was a scheduled flight from Los Angeles International Airport, Los Angeles, California to General Mitchell International Airport, Milwaukee, Wisconsin via Stapleton International Airport, Denver, Colorado with 38 on board. On January 18, 1969 at approximately 18:21 PST it crashed into Santa Monica Bay, Pacific Ocean about 11.5 miles west of Los Angeles International Airport four minutes after takeoff.
Rescuers (at the time) speculated that an explosion occurred aboard the plane, a Boeing 727. Three and a half hours after the crash three bodies had been found in the ocean along with parts of fuselage and a United States mail bag carrying letters with that day's postmark. Hope was dim for survivors because United's domestic flights do not carry liferafts or lifejackets. A Coast Guard spokesman said it looked "very doubtful that there could be anybody alive."
Up until 2013, United used "Flight 266" designation on its San Francisco-Chicago(O'Hare) route.
Two minutes into the flight, the pilots reported a fire warning for the No. 1 engine and that they were shutting it down. That action also shut down the generator on the No. 1 engine. Since the plane "...had been operating for 42 flight hours prior to the accident with the No. 3 generator inoperative, as allowed by the Minimum Equipment list," that left the No. 2 engine generator as the sole source for all electrical power on the aircraft. "Shortly after shutdown of the No. 1 engine, electrical power from the remaining generator (No. 2) was lost." All of the available evidence produced during the course of the investigation, did not enable the NTSB to determine why the number two generator also failed, after it became the sole source of power for the plane, nor why the "standby electrical system either was not activated or failed to function."
With the loss of all power to the lights and flight attitude instruments, while flying at night in instrument conditions, the pilots quickly became spatially disorientated and utterly helpless to know what inputs to the flight controls were necessary to keep the plane flying in the normal, upright attitude. Consequently they lost complete control of the aircraft and it crashed while in an abnormal attitude, killing all 38 aboard.
At the time, a battery powered back-up source for critical flight instruments was not required on commercial aircraft. The accident prompted the Federal Aviation Administration to require all transport category aircraft to have new backup instrumentation installed, and powered by a source independent of the generators.
Probable Cause 
- The Board determines that the probable cause of this accident was loss of attitude orientation during a night, instrument departure in which the 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 failed to function.
On January 13, 1969, just five days before the crash of United Flight 266, a Scandinavian Airlines DC-8 on final approach to Los Angeles International also crashed into Santa Monica Bay. The jet broke in half on impact, killing 15. Thirty people survived in a portion of the fuselage that remained afloat.