Denver

A Piper PA-31T "Cheyenne" and a Cessna 172P "Skyhawk" collided in midair during cruise flight at dusk and in visual meteorological conditions. The Cheyenne departed under visual flight rules (VFR) from a local airport northwest of Denver, and was proceeding direct at 7,800 feet to another local airport south of Denver. Radar indicated its ground speed was 230 knots. Its altitude encoder was transmitting intermittently. The Skyhawk departed VFR from the south airport and was en route to Cheyenne, Wyoming, at 7,300 feet. The pilot requested and was cleared to climb to 8,500 feet and penetrate class B airspace. Radar indicated its ground speed was 110 knots. The Skyhawk was flying in the suggested "VFR flyway"; the Cheyenne was not. When the controller observed the two airplanes converging, he asked the pilot of the Cheyenne for his altitude. He replied he was at 7,600 feet. The controller immediately issued a traffic advisory, but the pilot did not acknowledge. Both airplanes departed controlled flight: the Skyhawk struck a house, and the Cheyenne fell inverted into the backyard of a residence. Wreckage was scattered over a 24 square block area in west Denver. At the time of the accident, the controller was handling low altitude en route, arrival and departure traffic for both airports. Wreckage examination disclosed four slashes, consistent with propeller strikes, on top of the Cheyenne's right engine nacelle, the cabin above the right wing trailing edge, the empennage at the root of the dorsal fin, and at the tail cone. The Cheyenne was on a similar flight three days before the collision when the pilot was informed by air traffic control that the transponder was operating intermittently. According to recorded radar and voice communications from that flight, the transponder/encoder operated intermittently and the pilot was so advised. Examination of the Cheyenne's altimeter/encoder revealed a cold solder connection on pin 8 of the 15-pin altimeter connector. When the wire was resoldered to the pin, the information from the altimeters, encoder, and altitude serializer was normal.

The part 135 on-demand air taxi flight departed Denver, Colorado, with a destination of Columbus, Nebraska. Weather forecasts were for icing conditions along the entire route of flight. While en route, ATC advised the pilot of reported icing ahead. The pilot was cleared to climb to 19,000 feet to get on top of the clouds. The pilot reported 'some alternator problems,' and requested to divert to North Platte, Nebraska. He then elected to divert to McCook, Nebraska, due to the weather at North Platte. ATC lost communication with the pilot during the diversion. Witnesses reported the airplane circled the McCook Airport twice. According to them, the airplane entered a bank of about 45°, then stalled. Subsequently, it traveled about 190 feet through a stand of trees before coming to rest. Witnesses reported the airplane was covered with ice. One-half inch of mixed ice was found on a piece of windshield. Both alternators had one phase in the stator winding shorted.

The pilot reported to ATC that he intended to make an unscheduled fuel stop. ATC advised that Cedar City Airport was 15 minutes away. Radar vectors were requested and were issued. Although dark night conditions existed and the pilot controlled airport lighting was never activated, the pilot reported the airport in sight and was cleared for a visual approach. Three minutes later radar contact was lost. Impact occurred in mountainous terrain at 9,100 feet elevation about six miles east of the 5,622 foot elevation airport. Minimum safe altitude was 12,400 feet. All four occupants were killed.

The airplane was observed flying erratically at a low altitude, then enter a left wing, nose low attitude, impacting the ground in a residential area. Autopsies on both occupants included findings of massive traumatic injuries sustained during a struggle. The passenger reportedly planned to take his life by jumping out of an airplane over the mountains of Colorado because he believed he had an inoperable brain tumor.

After refueling in Denver, the medical evacuation flight was diverted from Aspen to Eagle to enplane the patient. IFR flight to Eagle was uneventful and radar service was terminated after the controller cleared the flight for the lDA-A approach to the Eagle Airport which shows a 239° inbound course. The last radio contact occurred when the crew replied 'we're 8 to 10 out and it's clear ahead' to Eagle radio in answer to a request for a base report. The flight collided with an 8,022 foot msl mountaintop bearing 298°, 3.88 miles from the airport while in the approach configuration. The safety board believes the flight was circling to land on runway 07, and the dark night prevented required visual lookout to avoid terrain obstructions. The Jeppesen approach charts used by the flightcrew did not accurately depict terrain obstructions within the 5-mile radius of the airport as stipulated in their legend. The safety board believes this could have mislead the flightcrew. All three occupants were killed.

On a night approach to Pueblo Memorial Airport while on a taxi flight from Denver, the pilot encountered technical problems with the power levers. The left engine was shut down then the airplane lost height, stalled and crashed on final. All four occupants were injured and the aircraft was destroyed.