Saranac Lake-Adirondack

The private pilot, who was experienced flying the accident airplane, was conducting a personal flight with three passengers on board the single-engine turboprop airplane. Earlier that day, the pilot flew uneventfully from his home airport to an airport about 1 hour away. During takeoff for the return flight, the airplane impacted wooded terrain about 0.5 mile northwest of the departure end of the runway. There were no witnesses to the accident, but the pilot's radio communications with flight service and on the common traffic advisory frequency were routine, and no distress calls were received. A postcrash fire consumed a majority of the wreckage, but no preimpact mechanical malfunctions were observed in the remaining wreckage. Examination of the propeller revealed that the propeller reversing lever guide pin had been installed backward. Without the guide pin installed correctly, the reversing lever and carbon block could dislodge from the beta ring and result in the propeller blades traveling to an uncommanded feathered position. However, examination of the propeller components indicated that the carbon block was in place and that the propeller was in the normal operating range at the time of impact. Additionally, the airplane had been operated for about 9 months and 100 flight hours since the most recent annual inspection had been completed, which was the last time the propeller was removed from and reinstalled on the engine. Therefore, the improper installation of the propeller reversing lever guide pin likely did not cause the accident. Review of the pilot's autopsy report revealed that he had severe coronary artery disease with 70 to 80 percent stenosis of the right coronary artery, 80 percent stenosis of the left anterior descending artery, and mitral annular calcification. The severe coronary artery disease combined with the mitral annular calcification placed the pilot at high risk for an acute cardiac event such as angina, a heart attack, or an arrhythmia. Such an event would have caused sudden symptoms such as chest pain, shortness of breath, palpitations, or fainting/loss of consciousness and would not have left any specific evidence to be found during the autopsy. It is likely that the pilot was acutely impaired or incapacitated at the time of the accident due to an acute cardiac event, which resulted in his loss of airplane control.

On IFR arrival, flight 4821 was cleared to intersection 17 northeast of airport at 6,000 feet, then for ILS runway 23 approach. Radar service was terminated 6.5 east of intersection. Radar data showed that flight crossed and then bracketed localizer. Flight intercepted glide slope from below about 7 miles outside of outer marker and thence deviated above glide slope. About 2 miles outside of marker, flight was at a full fly down deflection when it entered a descent varying from 1,200 to 2,000 fpm. Aircraft struck wooded mountain top 2.0 miles inside of outer marker (3.9 miles from runway) at elevation of 2,280 feet. Minimum altitude at marker was 3,600 feet. Glide slope elevation at point of impact was approximately 2,900 feet. Evidence was found of inadequate electrical ground path between radome and fuselage which, when combined with existing weather conditions, may have produced electrostatic discharge (precipitation static). Although post-accident tests were not conclusive, the safety board believes that the glide slope indications might have been unreliable due to precipitation static interference. Two occupants survived while two others (one pilot and one passenger) were killed.

The twin engine airplane departed Detroit-Wayne County Airport at the end of the afternoon on a flight to Saranac Lake-Adirondack Airport, NY. While descending by night and limited visibility due to snow falls, at an altitude of 3,100 feet, the airplane struck tree tops and crashed in a wooded area located on Mt Nye, in The Adirondack Mountain Range, about six miles south of Lake Placid. As the airplane failed to arrive, SAR operations were initiated but eventually abandoned after few days as no trace of the aircraft nor the three occupant was found. Walkers found the wreckage on 29 April 1979, about 16 miles southeast of Saranac Lake Airport.

The crew started the approach to Saranac Lake-Adirondack Airport by night and encountered poor visibility due to fog and snow showers. Unable to locate the runway, the captain decided to abandon the approach and initiated a go-around. Few minutes later, a second attempt to land was also abandoned for similar reasons. During a third attempt, the airplane passed below the MDA and once at an altitude of 2,140 feet, it struck trees and crashed in a wooded area located about 2 miles short of runway threshold. The aircraft was destroyed and all three crew members were killed.