or modulation. The missile has a small window in the rear with a laser sensor to detect the modulation of the light. Using this modulation, the missile steers itself, maintaining its position in the cone. The laser beam is zoomed during the missile flight so it has the same diameter (about 6 meters) throughout the missile flightpath. The laser beam-riding guidance system is smaller than a radio command one, and cheaper and simpler than semi-active laser guidance. The missile is also not prone to radio or optical jamming. On the other hand, the target has to be tracked by laser sight all the time, and the system can not be reliably used on the move. The missile's flight time to 4,000 meters is approximately 12 seconds. After 26 to 41 seconds, the missile self-destructs. Variants Cartridges firing the 9M117 Bastion missile; average armour penetration 550 mm Rolled homogeneous armour equivalency after ERA 100 mm 3UBK10 (MT-12) 100 mm 3UBK10-1 (T-55) 115 mm 3UBK10-2 (T-62) 100 mm 3UBK10-3 (BMP-3) Cartridges firing the 9M117M Kan Tandem HEAT missile; average armour penetration 600 mm RHAe after ERA 100 mm 3UBK10M (MT-12) 100 mm 3UBK10M-1 (T-55) 115 mm 3UBK10M-2 (T-62) 100 mm 3UBK10M-3 (BMP-3) Cartridges firing the 9M117M1 Arkan Tandem HEAT missile with extended range of 100–6,000 m; average armour penetration 750 mm RHAe after ERA 100 mm 3UBK23 (MT-12) 100 mm 3UBK23-1 (T-55) 115 mm 3UBK23-2 (T-62); average armour penetration 850 mm RHAe after ERA 100 mm 3UBK23-3 (BMP-3); firing Range, 100-5,500 m Sources Angelskiy, R., Otechestvennye protivotankovye kompleksy ("Domestic anti-tank systems"), Moscow, 2002, Footnotes External links Anti-tank guided missiles of Russia Anti-tank guided missiles of the Soviet Union Military equipment introduced in the 1980s