Piper PA-60 Aerostar (Ted Smith 600)

The pilot's failure to follow the published instrument approach procedure, which resulted in an early descent into trees and terrain. A factor was the night, instrument meteorological conditions.

The pilot's failure to maintain control of the airplane during a missed approach. Additional factors included the operator's inadequate oversight, the pilot's improper in-flight decision, conditions conducive to pilot fatigue, fog, and night.

The right main tire blowing out in flight, which resulted in a loss of directional control during landing.

Findings as to Causes and Contributing Factors:
1. For reasons not determined, the pilot did not adhere to the procedures depicted for the LOC DME-B approach to runway 16 at Penticton. As a result, the aircraft did not remain within the confines of protected airspace, was below the minimum safe altitude for the procedure turn, and struck the tower.
Findings as to Risk:
1. The approach was flown in weather conditions that virtually precluded the pilot from completing a landing.
Other Findings:
1. The pilot's flight medical certificate had expired one month prior to the accident, and no information could be found that he had submitted to an FAA medical during that time.

On vacating FL140, the aircraft's climb rate was so erratic at 140 KIAS that it seems likely that by then, the aircraft had already gathered sufficient ice to seriously affect its performance. If all the
turbocharger inlets had become partially blocked, then manually selecting both engines to alternate air induction should have introduced warmer air into the turbochargers and restored power. The description of engine operation in the Superstar manual states:
'If manifold pressure continues to decrease after opening the manual alternate air, it is an indication that turbocharger inlets are still restricted and the engine may become normally aspirated through the automatic alternate air door located below the induction air filter'.
Normal aspiration reduces the manifold pressure to ambient or less and at FL140 the ambient pressure is about 17.6 inches which is less than half the climb rated manifold pressure. That might explain the inability to climb above FL 160 but it would also have deprived the pilot of pressurisation. There was no change in his voice consistent with donning an oxygen mask so he may not have lost pressurisation completely. Nevertheless, since he lost control at around FL160 and 110 KIAS, and because the aircraft initially turned to the right, a combination of airframe icing and asymmetric power loss seem the most likely explanation for the sustained loss of control. The split in the EDP diaphragm which almost certainly occurred during this flight may have contributed to an asymmetric power problem. Alternatively, the pilot might have become mildly hypoxic and decided to begin an emergency descent. If so, he did not declare an emergency at the time he started to descend, although he did utter the word "SCOTTISH" after control was lost, so he was conscious even if his mental abilities had been impaired by hypoxia. On balance, the tone of his voice and his initial failure to respond to ATC messages suggested that the descent was begun through loss of control rather than a deliberate act followed by loss of control. At the time of the accident the aircraft had been flying below the freezing level (8,000 feet) for about five minutes and much of the airframe and induction system ice may have melted. The would-be rescuers would have taken at least five minutes to reach the crash site and so the fact that none of them reported seeing or treading on any ice was not surprising. Witness and propeller evidence indicated that power had been restored on at least one engine but there seemed to be insufficient power to climb out of Glen Lyon. The aircraft was out of control when it crashed at low speed from a sharp turning manoeuvre. Before this manoeuvre the pilot may have had partial control, albeit with a power problem which prevented him from climbing, and he finally lost control totally when he attempted to turn around within the confines of the Glen. He had no choice but to attempt the turn since, had he not turned, he would have flown into the side of the hill above the crash site.

Shortly after departure from Port Keats aerodrome, the pilot lost control of the aircraft for reasons unknown. Aerodynamic loading of the left wing in excess of the ultimate load limit occurred, resulting in an inflight breakup of the airframe. The investigation was unable to determine the circumstances that led to the loss of control and subsequent inflight break-up of the aircraft.

Due to the extreme degree of destruction of the aircraft, it was not possible to determine if a possible technical issue was the cause of the accident but this was not ruled out.

The pilot's in-flight loss of control due to physical incapacitation from sudden cardiac death secondary to an acute myocardial infarction.

The pilot's inadvertent shutdown of the wrong engine that resulted in the total loss of engine power. A factor was the loss of engine power due to fuel starvation when the left fuel boost pump failed.