[Reaganite Republican]

Another possibility:

“...SA-8 GECKO was used to down a cargo plane around Damascus by Syrian rebels last year which is highly mobile and has the range of 40,000 feet, well within distance of the reported height (36,000 ft).

http://therightscoop.com/heres-how-isis-could-have-shot-down-that-russian-airliner/

Something like this could have come from the US side, via the CIA Benghazi weapons bazaar... who knows what they were up to. And the Americans let a lot of Russian stuff go from Ghaddafi’s armory to the Islamists too... that’s on our, France, and UK’s hands.

[silverleaf]

There would have been ELINT from the associated radar

This would likely be detected easily in Egyptian territory with extensive Egyptian Israeli and UN/MFO monitoring

[BwanaNdege]

"The 9M33 missiles are 3.158 m (10.3 ft) long, weigh 126 kg (278 lb)"

Not exactly "Man-portable air-defense systems (MANPADS or MPADS) are shoulder-launched surface-to-air missiles (SAMs)."