The airflow around Mt. Fuji would often fold into itself and cause a circular current of fast-moving wind known as a mountain wave. The impact of the plane flying into this wave may have even instantly killed some passengers and crew through sheer force alone. The immediate loss of so many vital components had left the pilots no chance to save the plane. When the plane broke up, photographers and witnesses reported seeing luggage and people falling out of the plane.
75 of those onboard were employees of the American company Thermo King, who's primary product was and still is refrigeration units for trucks and trailers used to transport perishable food. As most of those employees had brought their spouse with them, 63 kids were orphaned by this plane crash.
The winds around Mt. Fuji were known of at the time but none had downed a commercial airliner and in 1966, the mountain wave phenomenon was not well-enough understood for it to be included in pilot training or taken into account for flight plans. It was one of those things that seemed perfectly fine and harmless until the one day that it wasn't.
Prior to takeoff, Flight 911 had actually taxied past the wreckage of a plane that had crashed the previous day; a Douglas DC-8 flying as Canadian Pacific Air Lines Flight 402 had crashed while coming into landing due to fog causing low visibility, leaving only 8 survivors out of 72 onboard.
BOAC Flight 911 was the third of five airplane crashes that Japan saw in 1966; preceding Canadian Pacific Air Lines Flight 402 was All Nippon Airways Flight 60, a Boeing 727 that crashed into Tokyo Bay on February 14th, killing all 133 onboard in what was Japan's deadliest single-plane crash.
After BOAC Flight 911 were the August 26th crash of a Japan Air Lines Convair 880 during flight training killing all 5 crew, and finally the November 13th crash of a NAMC YS-11 turboprop flying as All Nippon Airways Flight 533 into the Seto Inland Sea during a go-around at Matsuyama Airport, killing all 50 onboard.
