The Sukhoi Superjet-100 airliner probably crashed when it was trying to go around dense cumulus clouds, an official with Indonesia's transportation security agency said Monday.

The area where the airliner crashed is known for its bad weather conditions. The rescuers have not managed yet to lift the flight data recorders and the radio beacon of the airliner which are lying on the bottom of a ravine.

It is most likely that at during the demonstration flight the Sukhoi Superjet 100 failed to pass through thick clouds, Thomas Jamaluddin, the agency's representative says. There is a powerful mountain chain there which holds back the clouds and causes regular thunder storms.

The clouds can be several kilometers high in that zone. It is most likely that the airliner tried to by pass the cloud from below but the Salak mountain was higher in this place than the lower edge of the cloud, the Indonesian expert said.

Low clouds are also hampering the rescue operation which has been under way since Friday. The helicopters of Russia's Emergency Ministry could not explore the territory properly, the head of the information department of the Emergency Ministry Irina Andrianova says

"Currently, Russian and Indonesian rescuers are jointly searching for the remains of the victims and the fragments of the plane. The Russian rescuers are well trained mountain climbers and have all necessary equipment for working in such difficult environment.

The Superjet crashed into the mountain which has an almost vertical slope and a complicated relief. The foggy weather hampers the operation of small planes and helicopters and the evacuation of the remains of the victims. Nevertheless the rescue operation will continue."

Meanwhile, Russian psychologists are working with the relatives of the air-crash's victims, Andrianova says.

"A group of our psychologists is working in the airport of Jakarta. In particular, they are providing psychological aid to the employees of the Sukhoi company, who found themselves in a difficult situation."

The rescuers have filled three containers with the remains of the victims. In total there are 26 containers. Russian and Indonesian medical examiners are jointly conducting the identification of the remains.

The rescuers have split into two groups, Olga Kayukova, spokeswoman with the united aviation corporation said in an interview with "Russia 24" TV channel.

"The first group is searching for the remains and we hope that this work will be completed today. The second is looking for the fragments of the airliner. Now the work is under way at the foot of the mountain but apparently large fragments of the plane and the flight data recorders are lying in the ravine. In total of about 800 rescuers are working on the scene of the crash and in the camp."

The rescuers have only defined the area at the bottom of a 500 meter deep ravine, where the flight data recorders, the radio beacon and the on-board status measuring system are lying. But so far it was impossible to lift them, the spokesman of the Russian embassy in Jakarta Dmitry Solodov told the "Voice of Russia".

"The head of the Indonesian rescue agency said late Sunday that they have probably defined the black boxes' location. Now this information is being checked by Russian and Indonesian experts."

The Indonesian authorities also said Monday that the black boxes could be sent for decoding to Russia. In total it may take about one year to complete the investigation. Russia's Superjet-100 crashed on May 9 during a demonstration flight. There were 45 people on board including 8 Russians.

Voice of Russia