Page:CAB Aviation Accident Report, Mid-Air Collision on 15 December 1959.pdf/2

- 2 - An analytical study (Attachment A) based on all of the evidence shows that at the start of the 60-second period the colliding aircraft were separated 3.48 statute miles. At this time the F-86L's were positioned 129 degrees to the right rear of the Beechcraft and the Beechcraft was 67 degrees to the left of the nose of the aircraft of the jet formation leader. During the final 30-second period the F-86L's were positioned 110 degrees to the right rear of the Bonanza while the Bonanza was 26 degrees to the left of the nose of the aircraft of the jet formation leader. Separation between the planes was then 2.8 statute miles.

It is the conclusion of the Board that, from all the evidence, an overtaking situation occurred in which the F-86L's overtook the Bonanza from the right rear. The Board concludes that during closure there was sufficient opportunity for the jet formation leader to have seen the Beechcraft and to have avoided the collision, in accordance with the responsibility of the pilot of an overtaking aircraft. It is the further conclusion of the Board that the opportunities afforded Mr. Lewis were not sufficient to have expected him to have seen the jets.

Following the accident the Air National Guard unit at Cheyenne required that on missions which require a safety observer the pilot performing this responsibility will do so throughout the entire mission. The directive requires that the safety observer will not join formation even though that portion of the flight requiring a safety observer is completed. The unit also raised, for its jet aircraft, the flight altitudes specified for the control zone prior to the initial point 1,000 feet. The first action intends to enable all pilots flying as a flight to look for other aircraft. The second action intends to reduce collision exposure by greater traffic segregation.

. Investigation disclosed that on December 15, Mr. Gene A Lewis, the pilot of N 1839D, planned and prepared for a flight from St. Cloud, Minnesota, to Denver, Colorado, with an en route combined business and fueling stop at Dickinson, North Dakota. He departed St. Cloud at 0700 and flew, VFR - no flight plan - to Dickinson, arriving about 1050. There Mr. Lewis conducted his buisness and the Bonanza was fueled to capacity by adding 22.3 gallons of gasoline.

Mr. Lewis left DickinSon at 1235 and shortly after takeoff air-filed a VFR flight plan to Denver with the Dickinson FAA communications station. According to the flight plan he proposed to fly to Rapid City, South Dakota, direct to Denver, at 8,500 feet. He estimated 3 hours and 15 minutes en route with 5 hours of fuel aboard. About 1343 Pilot Lewis contacted Rapid City radio stating he was at 4,500 feet over the city, VFR to Denver. He requested and was furnished the latest winds aloft and weather appropriate to his flight.

About 1515 N 1839D called Cheyenne radio on 122.1 mcs. and requested the latest winds aloft. Mr. Lewis identified his flight as "Bonanza N 1839D" and stated he was VFR en route to Denver; he did not give his position or altitude. The controller furnished the most favorable winds aloft for a Bonanza en route from Cheyenne to Denver, which were between 8,000 and 11,000 feet.