"During the last plenary session of the Commission headed by Kazimierz Nowaczyk, the position on the issue of the timing and the primary reasons for the destruction of the left wing of the Tu-154M was coordinated… The destruction of the left wing of the Tu-154M was not initiated by a clash with a birch tree… The numerous damage of the left wing of the Tu-154M aircraft carried traces of an explosion," the commission said in a statement.
In June, the chairman of the IAC technical commission for the investigation of the crash, Alexei Morozov, told Sputnik no signs of explosives on the plane had been found during the 2010-2011 investigation. He pointed out that neither the scattering patterns of the wreckage, nor its condition, proved the theory about the explosion on board or the destruction of the plane in the air before collision with an obstacle. He recalled that the flight's altitude was below the safe height, which caused a collision with a tree and the subsequent crash.
The first Polish commission under the leadership of then-Interior Minister Jerzy Miller came to similar conclusions, saying the catastrophe was due to flying below the permissible height as the presidential plane started landing despite thick fog. The current Polish authorities did not agree with the IAC report and the conclusions of the Miller commission and decided to establish a second commission.
The new Polish commission presented the first results of its work in September 2016, saying that the jet started to disintegrate 900 meters (about 3,000 feet) away from the crash site with the last seconds of the flight recorders’ materials having been deleted.
The commission stated that it had succeeded in getting access to the full versions of the records showing that generator, engine and devices responsible for altimetry broke shortly before the crash. Polish Defense Minister Antoni Macierewicz decided to disclose the documents linked to the plane crash.
In April 2017, the Polish commission issued new materials placing the responsibility on Russian air traffic controllers. The materials also said that a blast hit the jet before it hit the ground. The IAC rejected the conclusions made by the Polish commission as the technical committee has not revealed any traces of the explosives’ impact on the plane. The IAC also rejected the Polish commission’s allegations about the deletion of the last seconds of the flight recorders’ materials.