Flight crew fatigue caused a landing accident of Sukhoi Superjet at Keflavík Airport, Iceland in July 2013, according to the Icelandic Transportation Safety Board.
On July 21, at 04:03 hours local time, the Sukhoi Superjet took off from runway 20 at Keflavík Airport for flight testing with a crew of five on board. The airplane had been undergoing certification flight tests for almost one month at Keflavík Airport. This was the crew’s fourth test flight since their work shift started at 18:00 the day before. The pilot flying was sitting in the right cockpit pilot seat.
Seven approaches and go-arounds were performed with possible landing gear touchdown to runway 20, followed by two to runway 11.
During the final approach to runway 11 at 05:22, the landing gear was selected down. The approach was normal. At 05:23 the flight crew initiated the 9th test of the flight. The purpose of the test was to simulate a CAT IIIA automatic approach, close to the airplane’s maximum landing weight limit, while in crosswind exceeding 10 m/s (19.5 knots), with a critical engine failure occurring at radio altitude of 25 feet, resulting in a low pass/missed approach.
When the aircraft was at radio altitude of about 10 ft the flight certification expert sitting in the jump seat in the cockpit shut down the right engine using the ENG MASTER SWITCH.
After the right engine was shut off, the right autothrottle disconnected and the right throttle lever stopped moving to idle, while the left autothrottle continued moving the left throttle lever back to idle.
At a radio altitude of about 4 feet the pilot flying disengaged the autopilot. This caused disengagement of all autopilot/flight director control modes and the left autothrottle reverted to SPEED mode. When the left autothrottle reverted to SPEED mode, the left throttle lever had already reached IDLE. At that time the airplane speed had reduced down below the “limit selectable speed”, so the left autothrottle started moving the left throttle lever forward.
The pilot flying pressed the TOGA (Take Off/Go Around) button on the right throttle lever to initiate a goaround. Almost simultaneously the main landing gear touched the runway.
The left engine autothrottle and flight director then disengaged automatically. The pilot flying then noticed at the primary flight display that the go-around mode had not engaged when he selected the TOGA switch. The pilot flying also noticed that the flight director was not available and that the autothrottle was switched off.
The pilot flying then started to perform a go around in manual mode, setting the right (inoperative) engine throttle lever to TO/GA, pitched-up the aircraft and ordered landing gear retraction.
During the go-around procedure, after the landing gear was retracted, the airplane started to loose speed. The airplane stopped climbing having reached a maximum radio altitude of 27 feet at and then started to descend. The speed decreased further, below 120 knots. The pilot flying then set the right throttle lever to MAX. The speed continued to decrease and the pilot flying, now aware of both the speed loss and the loss of altitude, reduced the nose pitch to try to counteract stalling.
The airplane’s aural warning “LANDING GEAR NOT DOWN” triggered at that time.
The pilot flying realized that engine was not in takeoff mode and checked engine power settings. He found out that operating left engine was in N1=50% mode and realized that he had been controlling the inoperative engine.
The pilot flying set the left engine throttle lever to MAX. The airplane was still descending and while the left engine was spooling up, the airplane hit the runway.
As the landing gear was in the up position, it was the fuselage aft lower belly that hit the runway first. This was on the left side of the runway center line, as due to the loss of airspeed and the crosswind the airplane had drifted to the left.
This was followed by the engines’ cowlings touching the runway. As the airplane nose had been turned into the wind when it hit the runway, it initially veered to the right, as it skidded down the runway, across the runway centerline. The pilot flying counteracted this movement with a left rudder input and steered the airplane back towards the runway centerline.
The pilot flying set both throttle lever’s to IDLE position at and then to deploy the thrust reversers. The airplane skidded off the end of runway 11 and came to rest after having passed 163 meters beyond the threshold of runway 29.
After the airplane had come to a stop, the pilot in command, who was also the pilot flying, ordered an emergency evacuation. The forward left door was opened by the cockpit crew, but the emergency escape slide did not deploy. The crew member operating the test equipment in the cabin opened the rear left door and its slide deployed. The cockpit crew then opened the forward right
door. The slide deployed, but due to the crosswind it blew underneath the belly of the airplane and was unusable. The whole crew evacuated the airplane via the rear left door.
The Icelandic Transportation Safety Board determined that the most probably cause of the accident to be flight crew fatigue, which resulted in the flight crew advancing the incorrect throttle lever to TO/GA position. This occured after the airplane touched the runway, which had resulted in the automatic flight control system shutting off.