American Flight 910 took off from San Francisco at 23:05 for a flight to Dallas. At 06:56 the following morning, a Temco Swift airplane (N3858K, cn 3558) departed Denton for Dallas-Love Field. At that time, Flight 910 had received clearance for a runway 13 approach. The First Officer was making the final approach down the ILS glidepath and localizer and was maintaining visual contact with the ground. During the approach the crew heard the tower give instructions to a light aircraft. At an altitude of 400 feet the First Officer sighted the plane as it came into view from under the fuselage of the descending DC-6, almost abeam of his side cockpit window and slightly lower. Both aircraft collided; Swift fell in a left spin and crashed 4410 feet from the runway. The DC-6 landed safely. PROBABLE CAUSE: “The Swift pilot’s failure to exercise reasonable prudence in his approach; error in judgement of the situation on the part of the controller was a contributing factor.”