Well, now. There's an SA-7 SAM. But it's a shoulder fired heat seeker. It wouldn't hit a plane head on.
Walt
Not necessarily true. The IR locks onto the greatest heat source. On a jet aircraft this usually the exaust cone. Smaller aircraft with reciprocating engines still generate enough heat through the engine nacelle for an SA-7 to lock on from the front and below, but is often dispersed due to prop-wash. This means the missle will probably guide, but will not have a pinpoint target (thus missing a nacelle,but hitting the plane). Even a sunlight reflection from a windshield could produce a lock if the shooters were lucky.
Where a heat-seeking missle strikes an aircraft has to do with the type and location of the engin and the direction from which it is fired. It does not take great amounts of heat, and the hottest source wins, which is why flares works so well as a defensive measure.
The report that it hit the plane head-on, is not enough to dismiss the report. Only to raise cautionary red-flags.