MH17 was the, "Wrong plane," says Ukrainian fighter pilot after shootdown.

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43. The performance and designed role of the SU-25 makes this story unlikely

The SU-25 is designed for close air support and ground attack, not air to air combat. The SU-25's that the Ukraine operates are the older ones, so it is unlikely they have air to air radar installed. It is capable of carrying short range heat seeking air to air missiles, but that is intended for self defense, not the interception of aircraft.

The maximum altitude of a SU-25 with no weapons is 23,000 feet, with a full weapons load the maximum altitude is 16,000 feet. Being designed for low altitude attack missions, the engines would have been optimized to perform best at low altitudes so at 23,000 feet the SU-25 would have been SLOWER then the MH17 Boeing 777-200ER that was at a reported 33,000 feet and cruising at 560 mph, presuming no tail or head wind.

If the SU-25 was armed, it should have been armed mostly with ground attack weapons and probably a pair of heat seeking air to air missiles for self defense, which would have reduced the maximum altitude and airspeed it was capable of reaching. So how does the SU-25 see the Boeing 777? How does the SU-25 know it is not an enemy fighter? If satisfactory answers to the prior two questions exist, there remains the question how does the SU-25 get close enough to lock on to the 777 with the air to air missiles?