Experts identify possible mistakes of pilots of Superjet that burnt out at Sheremetyevo Airport
Experts believe that actions of the crew turned the situation from the emergency landing to the fatal crash.
Experts explored the flight recorders of Aeroflot’s Sukhoi Superjet 100 that had accident at the Sheremetyevo Airport on May 5, reports Kommersant with reference to a source familiar with the investigation. Experts believe that the fatal crash was caused by mistakes of pilots who drove at high speed before the landing which forced tha plane into a dive.
According to the flight recorders, the plane that was on its way from Moscow to Murmansk was struck by lightning in 15 minutes after the take-off. The lightning struck the plane’s head and left the indicative mark. Due to the lightning, thunder protection of the SSJ 100 was activated. The power source of the plane switched off, and the electric supply was switched to accumulator batteries (Emergency Electrical configuration, EEC Mode). After that, Direct Mode was switched on - just like it happens in all modern planes. The onboard digital computer of Superjet stopped correcting the pilots’ possible mistakes.
Experts believe that the off-nominal situation appeared, however it was not the catastrophic situation. Order of activities during the EEC and Direct Mode is detailed in instructions for the crew members and in working instruction of SSJ 100. In particular, when the EEC Mode is turned on, there’s no need to land immediately.
Manufacturer of Supejet states that the plane can be in the air with non-functioning generators “for quite some time” - in order to reach the closest airdrome and land there. Whenever necessary, it can even turn to the second round for another approach. When the mode is on, there’s no need to send out a mayday call. Pilots must send an emergency call that implies that there’s no danger of life of people on board. It is noted that due to this reason, fire fighters did not meet the plane. They only arrive when the mayday call is sent, and Superjet did not send it.
Experts believe that both problems allowed the pilots to land the plane at the airport of departure even taking into account the overweight due to full fuel tanks.
It follows from the data of the flight recorders that on the second attempt the SSJ 100 pilots succeeded in landing in compliance with all regulatory requirements. The pilots had to fly the aircraft with the autopilot turned off and the autothrust. For this reason, they may have flown over the estimated landing point at the beginning of the runway. In the middle of the runway, the plane had not yet touched it with wheels, and the pilots tried to ‘press’ it to it, increasing the engine operating mode and dropping the nose of the aircraft. It is this maneuver that led to the catastrophe, experts say.
The aircraft landed with significantly increased indicated air and vertical speeds and grounded "on three points." The decreasing front landing gear flung the liner up, resulting in a series of bounces from the runway. The second strike on the runway created an overload that significantly exceeded the limit for this aircraft. The rear landing gear pierced the fuel tanks, causing the fire.
Another mistake of the pilots named by the experts is the attempt to land the plane after the first strike on the runway. The instructions prescribe the crew to stop landing after the first bounce and begin an emergency take-off.
The source of the publication believes that at this point it can already be said that the experts have reconstructed the situation aboard the Superjet. Now the investigation should establish exactly who of the pilots committed dangerous acts. The SSJ 100 is not piloted with traditional handwheels, but with the help of joystick handles through which pilots send commands to the onboard computer, that is, identifying the author of the erroneous actions will not take much time, the source said.