Russia's Tu-154 plane, which crashed into the Black Sea last Thursday, "by tragic accidence" might have been shot down by a missile of Ukraine's S-200 air defence missile system during a Ukrainian air defence exercise, an official of the Almaz company, which developed the S-200, has told RIA Novosti. The official said that, in all probability, the system's guidance station locked onto the passenger airliner instead of a Reis pilotless reconnaissance aircraft which was used as the target during the exercise. According to the expert, the S-200 system, which has long been withdrawn from service in Russia but which remains in service with Ukraine's air defence forces, is capable of hitting aerial targets, at a very high kill probability, at a range of 250 kilometres and at altitudes ranging from 300 metres to 35 kilometres. The system can also fire to 350 kilometres, but with reduced effectiveness. At the moment of the accident, the Tu-154 plane might be within the killing zone of the S-200 system which fired at aerial targets from Cape Opuk on the Crimean Peninsula. The Almaz official said the speed of the Reis pilotless aircraft exceeded that of the Tu-154, and it was much closer to the guidance station. This is why, after one revolution of the system's antenna, Reis left the guidance station's target detection zone, while the Tu-154 was still within it. Besides, the Tu-154 had a much larger "effective target area" than Reis, so it sent a more powerful "echo signal" to the guidance station. Therefore, the guidance station of the S-200 system might have locked onto the more powerful signal and indicated it on the radar screen as an aerial target to be destroyed, the Almaz expert said. The warhead of the S-200 system's missile comprises over 10,000 steel balls, five centimetres in diameter. In all probability, the plane was riddled with these balls which provoked the explosion of its fuel tanks. The Almaz official said that in former years, including Soviet times, live firings at aerial targets had never been held on the Crimean Peninsula because of nearby air routes.