Northwesternmost debris on this map has a distance of 16 km from the main impact site and a distance of 35 km from the BUK launch site alleged by the SBU. The mapping is cut off there, so probably debris can be found even further to the north west.
More likely the NorthWest Plume of debris is light airborne debris from the impact location. The Eastern leg is more likely ballistic debris on or near the flight-path
Wind records at the time are roughly South-East i.e. light debris will fall North-West. The planned track has a significant Easterly component.