An initial probe found the aircraft had experienced a problem as it was leaving the airport zone. The plane caught fire three minutes into the flight at an altitude of 2,400m (8,000ft). A fire broke out in one of its engines.
The plane, which was initially headed west, turned back to the airport immediately the problem arose. Then, the plane crashed into the ground.
No distress calls were made.
Eliot Higgins of Bellingcat tweeted photographs of a Tor nose section with its distinctive canards, claimed to be taken at the crash site.
Two unverified images allegedly taken near the crash site supposedly showing part of a Tor M-1 missile.
Iran indeed has Tor low to medium altitude, short-range surface-to-air missile systems obtained from Russia.
The theory is that Iran accidentally launched a surface-to-air missile that hit Flight PS752. This version suggests the launch of a missile at an allegedly unclear target in the vicinity of the capital’s airport where there is continual movement of passenger liners.
The questions remain: At what kind of a supposed hostile target could the Iranians be aiming? How could a single hostile plane the size of a Boeing 737-800 have been imagined near Tehran, far from any site of a possible US attack? How might this kind of a singular hostile target have appeared near the capital unnoticed?
9A330 of the Tor-M1 air defence system (rear view of the chassis).
9K331 Tor-M1
The Tor missile system is an all-weather low to medium altitude, short-range surface-to-air missile system designed for destroying airplanes, helicopters, cruise missiles, precision guided munitions, unmanned aerial vehicles and short-range ballistic threats (anti-munitions). Originally developed by the Soviet Union under the GRAU designation 9K330 Tor, the system is commonly known by its NATO reporting name, SA-15 “Gauntlet”.
“Tor-M1”, introduced in 1991 with the 9M331 missile, with greatly improved missile accuracy and the ability to engage two targets simultaneously, minimum range 1.5 km (0.93 mi), minimum height 10 m.
Even while the Tor was being introduced into service, work started on improving the system, resulting in an enhanced version, the Tor-M1. Many improvements over the original system were made; these included the addition of a second fire control channel, allowing two targets to be engaged at once; as well as upgrades to the optical tracking system and computer equipment. ECM protection and warhead design were also modified, as was the ammunition handling system. State tests, conducted between March and December 1989, showed that the result was a system which could engage more targets in a shorter time frame with reaction times reduced by over a second and an increased probability of target destruction. Further modifications occurred partly as a response of insight gained from the 1995 NATO bombing in Bosnia and Herzegovina resulting in the Tor-M1-1, or Tor-M1V, which offered improved network connectivity and ECM functions as well as protection against countermeasures.
In 1993 Tor, in the test conditions reflecting targets enjoying defensive countermeasures, repeatedly downed small-sized rockets (similar to the much later and static complexes Iron Dome 1 target) with a 100% success rate.
The rockets were developed for the interception of small, aggressively maneuvering targets.
Weighing 167 kilograms (368 lb), the 9M330 missile is 3 metres (9.8 ft) long, carries a 15 kilograms (33 lb) warhead and has a peak speed of around Mach 2.8. Using command guidance and radar controlled proximity fuzes, the missiles can maneuver at up to 30 g and engage targets flying at up to Mach 2.
Iran has acquired 29 systems and successfully tests TOR-M1 missiles already in 2007.
Most possible, the Iranian system is automated.