The studies of the aircraft indicate that there was nothing wrong with the automatic speed regulation system, nor with the engines, as previously speculated over. The main theses of the investigators thus is human error from the pilots, newspaper Kommersant reports. -The reason behind the tragedy is probably connected with the qualifications of the pilots, one of the investigators told the newspaper. The radio communication between the pilots and the ground tower indicates that the pilots were not confident with the management of the plane. After having failed to land on a first attempt, the pilots started to quarrel how to proceed. The pilots are also reported to have lacked flying experience from the new Boeing 737 engine. They had both of them had all their career with the Russian-made Tu-134 aircrafts.
