The story says the pilot say the smoke trail. That would indicate to me the rocket was still under power. Amateur rockets will easily go this high. 8 miles from the airport is a decent distance and would be adequate for most rockets.
Something doesn’t add up though. We are supposed to believe a commercial jet was at 5000 feet of altitude 8 miles from the runway. The plane had taken off and should have been gaining altitude.
Do any pilots on here know what altitude the jet should have been at?
IMO it seems more likely a govt attempt to squash amateur rockets than anything else. A ground launched missile would have went for the engines and not the cockpit.