Now that decoding of the flight data recorders of the crashed Boeing is complete, an unnamed source told Russian daily Kommersant that pilot error is now dominating the investigation as the probable cause.
It appears that while trying to gain altitude after an unsuccessful landing attempt in bad weather, one of the pilots pulled the control stick up too much, causing a stall break and an uncontrollable nosedive.
The Interstate Aviation Committee believes that the official results of the decoding will be made public within a week or two.
Meanwhile, according to Kommersant’s sources, the recorder revealed that flight FZ981 had made two attempts to land in automatic mode, and since a veering squall wind hampered the second attempt, the pilot decided to make a third approach for landing in manual mode.
One of the pilots pressed the TOGA (Take off. Go around) button and turned off the autopilot, writes the daily.
Anonymous experts Kommersant talked to believe the pilot did not manage the diving rudder and horizontal stabilizer, which steer the plane in opposite directions – down and up, respectively.
When the pilot pulled up, he put both the rudder and stabilizer in a sharp climb mode, somewhat fighter-jet style, plus enacted the TOGA regime’s retracted flaps, decreasing ascending force. As a result, the aircraft lost speed and got into the beyond-stall angle of approach. All this led to an uncontrollable dive, the experts believe.
— RT (@RT_com) March 23, 2016
At that moment, the voice recorder is said to have registered a conflict between pilots. The pilot that tried to force the aircraft to gain altitude apparently turned the engines to powerful take-off mode, forcing the aircraft to continue its climb.
The other pilot believed the situation was dangerous and apparently did the opposite: he pushed his own control over to bring the Boeing’s nose down and prevent the sweeping up, while yelling at his colleague to stop doing it that way.
“Wait! Where are you flying? Stop! Stop!” a voice on the recorder reportedly yelled.
— RT (@RT_com) March 20, 2016
The pilots’ contrary actions caused the controls of the aircraft to ‘split’: the Boeing 737’s onboard computer was receiving mutually-exclusive commands from the two controls, which are usually operated synchronously. This rendered the plane out of control.
When they felt the plummeting sensation, the crew coordinated their actions, but it was already too late. The Boeing 737-800 was roaring at 325kph downwards at an angle of about 45 degrees. It burst into flames upon collision with the ground, killing all 62 people on board.
During the last seconds before the collision both pilots were screaming with terror, Kommersant reports.
— RT (@RT_com) March 27, 2016
On March 20, Russia’s Investigative Committee named pilot error or technical failure as the prime theories as to the cause of the Flydubai’s Boeing 737-800 crash in Rostov-on-Don on March 19.
It is unclear from the recording which pilot was doing what, Kommersant notes. At first the investigators even believed that only one man was speaking the whole time. Now, to identify the voices of the deceased pilots, the expertise of their former colleagues and even relatives may be needed.