Complex sentence: A Lithuanian board of investigation appointed to determine the cause of the catastrophe concluded that the pilots were properly qualified to accomplish the mission; from the technical standpoint the airplane was properly outfitted; and the most difficult part of the flight was executed with great precision.
Split into simpler sentences: A Lithuanian board of investigation was appointed to determine the cause of the catastrophe. It concluded that the pilots were properly qualified to accomplish the mission; from a technical standpoint the airplane was properly outfitted, and the most difficult part of the flight was executed with great precision.