Alaska Airlines Flight 1866 was a scheduled flight from Seattle, Washington, to Juneau, Alaska, that tragically ended in disaster on a September evening. The aircraft, a Boeing 727-100, departed Seattle at approximately 6:36 PM, carrying 104 passengers and 7 crew members. As the plane approached Juneau, it encountered severe weather, including heavy rain and turbulence. The pilots attempted to navigate through the storm but mistakenly descended into a hilly terrain obscured by the weather. At around 7:55 PM, just six minutes before its scheduled landing, the aircraft collided with a mountainside near the Mendenhall Glacier, killing everyone on board instantly.

The accident was investigated by the National Transportation Safety Board (NTSB). They concluded that the probable cause of the crash was the flight crew's failure to comprehend their proximity to sloped terrain while in severe weather conditions. The investigation identified issues related to flight crew training, operational procedures, and the limitations of onboard navigational instruments during adverse weather. Measures were subsequently taken to enhance the safety protocols for flights in Alaska, focusing on pilot training programs and aircraft technology improvements.

Alaska Airlines Flight 1866 remains one of the deadliest aviation accidents in Alaskan history, drawing widespread attention to aviation safety in the challenging weather conditions often experienced in the region. The tragedy led to shifts in aviation regulations, particularly concerning flight operations in adverse weather and pilot training requirements, which contributed to the overall enhancement of flight safety standards in the United States.