Massive plane crashes in Russia. Why is this happening?

On October 17th, an Su-34 military plane went down in the Russian city of Yeisk. It crashed straight into a high-rise building. The pilot managed to eject, but 15 civilians died and 25 were hospitalized. The Su-34 is one of the most advanced Russian aircraft, which crashed due to a technical malfunction. A large fire broke out after the crash and explosions were heard. Then the media reported that the plane was with full tanks of fuel, and with a full set of weapons. Immediately after takeoff, its engine caught fire and it lost control. Just five days later, history repeated itself. On October 23rd an Su-30 fighter jet crashed into a private house in Irkutsk. Both pilots died. The media reported later that the pilots were performing a test flight after repairs of the plane. There was a depressurization issue and the oxygen masks were faulty, so the pilots died right there in the cockpit. When the plane ran out of fuel, it crashed like a stone into a civilian home. Even if we as