An airliner cruising at around 30,000 ft altitude would be well above the coverage of shoulder-fired man-portable missile systems, which typically can engage targets flying at up to around 10,000 ft.
Ukraine does have in its inventory long-range Soviet-era missile systems such as the SA-2, -3, -5 and -12 that would have no difficulty downing a target flying at 30,000 ft. However, these systems are deployed at permanent launch sites that have launchers and associated radars located at specific locations. Their operators would have a good idea of the air traffic present in the surrounding area, so would be unlikely to mistake an airliner for a combat aircraft.
Downing an airliner flying at normal cruise altitude would require a mobile SAM system such as a Kub (known to the West as the SA-6 ‘Gainful) or the Buk (known to the West as the SA-11 ‘Gadfly’). Both are in Ukrainian service.
The Kub can cope with targets flying at up to 26,000 ft (8,000 m), so cannot reach the reported cruise height of the airliner. Buk coverage extends up to 72,000 ft (22,000 m). Its maximum range is 32 km.
When fielded, a Buk firing battery consists of:
the 9S18M1Target Acquisition Radar used to acquire potential aerial targets, and transmit their position and tracks to:
the 9S470M1 Command Post (CP) vehicle (contains the missile battery’s data display and control system; digital fire-control computer, which assigns targets to individual launchers, and computes the engagement)
one or more 9A310M1S launchers each armed with four radar-guided missiles.
All three of these systems are vehicle-mounted.
In a normal engagement, all three would operate as an integrated weapon system, and the crew of the Command Post vehicle are likely to have a good idea of the local air activity.
However, a Buk launcher can also operate in stand-alone mode. Its built-in radar is normally used to track the target being engaged, but can be operated in a target-detection mode, allowing it to autonomously engage targets that were present in the radar’s forward field of view.
Although it has it own Identification Friend or Foe (IFF) system, this is only able to establish whether the target being tracked is a friendly aircraft. It is the electronic equivalent of a sentry calling out “Who goes there?” If there is no reply, all you know is that it is not one of your own side’s combat aircraft. It would not give you a warning that you were tracking an airliner.
Operating Buk hardware would require a trained crew – personnel who are currently trained operators, or who learned how to operate the hardware while serving as conscripts.