12/31/2009. This trainer, call sign 'Blue 02', was converted into the SOTN (samolyot optiko-televizionnovo nablyudeniya, optical TV surveillance aircraft). Its duties included collaboration with three Tupolev Tu-154LL control-system test beds and approach trainers in research for the ideal Buran (the Soviet space shuttle) approach trajectory, checking monitoring of the Buran flight-control system, training Buran pilots and navigator I system operators, and acting as chase plane.
The SOTN would first rendezvous at about 59,055 ft (18,000 m) with the target aircraft. Until the Buran flew, targets included a modified MiG-25RB ('Red 02'), a MiG-31 ('Red 97') and the 'BTS-001' (registration SSSR-3501002), which was a Buran fitted with four AL-31 engines and a longer nose gear for taking off under its own power. It would then throttle back, lower its landing gear and fly down the steep glide path whilst recording.
Stage A comprised fifteen flights to check out the system; some signals were corrupted by radar altimeters of aircraft in the vicinity. Stage B, in September-October 1986, established optimum target distance at 33 ft (10 m). Stage C, held at Eupatoria, Crimea, on October 11 to 16, 1986, included ten flights with the total system. On the Buran's first and only space mission in 1988, the SOTN, flown by Magomed Tolboyev, intercepted the vehicle after re-entry and videotaped its entire approach and landing.