1959 Washington Boeing 707 crash

On October 19, 1959, a Boeing 707, registration N7071, was on a demonstration and acceptance flight before being delivered to Braniff International Airways. The flight was also used to instruct Braniff pilots. During some maneuvers, flight control was lost and aerodynamic forces caused three of the 707's four engines to be separated from the aircraft. Subsequently, the plane crash landed near Arlington, Washington. All four crew members were killed, while four observing passengers, located in the rear section of the plane, were injured but survived.

Flight

The aircraft took off from Boeing Field at around 13:30 local time for a flight expected to last 4 hours and 15 minutes. Pilot-trainee Berke was in the left seat (conventionally occupied by the pilot in command), with instructor-pilot Baum occupying the right seat. After the takeoff, a series of maneuvers were demonstrated by Baum, after which Berke executed them himself. One of these maneuvers was the Dutch roll, which Baum initiated and which Berke then was assigned to recover from. After making the recoveries in a clean configuration (no flaps or landing gear extended), the aircraft was slowed down to 155 kn and the flaps were extended to 40 degrees. Even though the absolute maximum bank angle permitted during the Dutch roll was 25 degrees, the bank exceeded this limitation. The pilot riding as a passenger reminded Baum of these restrictions, which he acknowledged.

Baum then suggested attempting a recovery from a nose-right position, and initiated a Dutch roll with a bank angle of 40 to 60 degrees. The aircraft completed several of these rolls before a recovery was attempted, and Berke banked to the right while the aircraft was already banking to the right. The aircraft yawed to the right and the bank angle increased past 90 degrees. Baum used left aileron to induce a violent left roll. The aircraft rotated around several times to the left, before the plane settled in an inverted nose-down position. The crew managed to recover from the dive; however, engine number 1 and engine number 4 had detached completely, with small fires burning where the engines had been. Engine number 2 was on fire and hanging downwards due to its forward mount failing. It soon detached completely; however, an intense fire remained on the wing.

The aircraft had broken through the clouds and the pilot riding as a passenger suggested ditching in nearby Lake Cavanaugh, so the four passengers moved to the rear of the cabin to prepare for a possible water landing. Running the remaining engine (number 3) alone would have been enough to reach the nearest airport; however, the fire raging in the left wing destroyed the left inboard aileron and disabled the outboard ailerons. Additionally, the loss of power caused by the loss of three engines disabled the inboard spoilers and the rudder boost, leaving only the right inboard aileron and outboard spoilers. Fire damage on the wing reduced its lift, leading to a rolling momentum. This roll could temporarily be countered for by reducing the power of the remaining engine. Before the impact, that engine was shut down. Eyewitnesses reported that large portions of the left wing had burned away.

The crew elected to attempt a landing in an open field; however, they did not have enough altitude and the plane first impacted 110 ft trees approximately 1/2 mi short of the field. A 16 ft portion of the left wing was torn off after hitting a tree. The left wing dropped and hit the ground, followed by the nose section, which was destroyed by the impact and the ensuing fire, killing all four crew members. The aft section, where the four survivors were located, detached aft of the wings and came to rest in the North Fork of the Stillaguamish River.