If the jet was shot, experts said it is likely to be at the hands of an advanced radar-guided surface-to-air missile. The Boeing 777 was travelling at an altitude of 33,000 feet, above the altitude that the Ukrainian aviation authority deemed safe on that route. But only such a powerful rocket would be able to hit this target.
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Usually rebel militia and terrorists have access to less-complicated missiles that are launched from a shoulder-mounted weapon and that cannot travel as high as the plane was flying.
"It is relatively unusual. The pictures that we are used to seeing of insurgent groups, rebel groups, are of using lower sophisticated weapons…which are relatively easy to operate…against a target at relatively short range," Edward Hunt, senior defense consultant at IHS Jane's, told CNBC in a TV interview.
"These kind of systems that would have been used against an aircraft at 30,000 feet are more complicated and not usually found outside state and national armed forces."
Questions over whether this was a deliberate attack or an accident still remain. Hunt said that weapons like this often have computer system to recognize a civil aircraft, but in this instance the check was not made or was not able to be made.
One of the first things investigators think about after an aircraft incident is the black box – a recording device in the plane – that can give an idea of what happened on board. But it has its limitations.
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It needs to be physically located and not damaged. In the case of flight MH17, the rocket would have cut off power supply to the black box leaving only a few seconds of useful information on it.