Mount Slesse
The TCA North Star Accident
by
Adrian Walker
Sixty years ago a Trans Canada Airlines 4-engined Canadair North Star, registration CF-TFD, crashed into Mount Slesse, 30 kilometres south-east of Chilliwack, killing all 62 people on board.
An intense storm was on the south coast with a cold front along the Cascade Mountains near Abbotsford. West-southwesterly winds at 20,000 feet were almost 100 knots, and only slightly less at 10,000 feet. Moderate turbulence and icing were expected, with extreme turbulence below 12,000 feet over the mountains.
The aircraft had taken off from Vancouver at supper time on 9th December 1956, planning to follow the airway Red 25 through Abbotsford and Cultus Lake, and then via Red 44 to Princeton and onward to Calgary. Fifty kilometres west of Princeton while climbing through 19,500 feet, a fire warning light came on for the number two engine (left inner engine). The captain made a turn to depart the airway, shut down the engine, and 6 minutes later reported in a further right turn to head back to Vancouver. He received a clearance to return via the same Red 44 route, but he reported rapidly losing altitude – in fact two other aircraft had reported strong subsidence over the mountains. Most likely concerned about altitude, he requested a change in route to the much more northerly airway Green 1 which went from Princeton through Hope to Vancouver, and which had slightly lower minimum altitudes. He eventually obtained that clearance but by this time it was some 25 kilometres north of his position. The pilots’ workload was clearly extremely high which is suggested by the comment from another aircraft that night: “our weather was such that it required nearly our whole attention” just to fly the aircraft, which may explain the limited information passed on during some of the radio transmissions.
A radar plot shows him paralleling Red 44 but 11 kilometers to its south. The Hope beacon was later found to be unreliable to the southeast, and radio range technology, especially in the mountains and in heavy precipitation, was known to have signal errors. Another senior pilot later indicated that the area between Chilliwack and Hope was without a reliable radio guidance signal, and the investigation concluded that under the weather conditions that night, the radio range signal in the Hope area was likely zero. The flight was asked to report by Hope, and did so from its position 32 kilometres abeam the beacon. That was the last transmission from the aircraft.
Five months later, the wreckage was found on the Third Peak of Mount Slesse, only 75 feet from its summit, at an altitude of 7,700 feet. The aircraft had exploded on impact and only relatively small pieces remained, much of which fell 2,000 feet down the almost sheer cliffs of the mountain. The human remains which were found were buried under cairns high on the mountainside.
The subsequent investigation could neither determine why the aircraft was not on Green 1, nor why it was at such a low altitude as to hit the mountain. The evidence, in fact, shows that the pilots maintained a track close to their original clearance, but indicated their surprise at the strength of the headwinds they were experiencing. A combination of icing in heavy snow, and especially strong subsidence were assumed to be the cause of the altitude loss, and nowadays we would also include altimeter pressure errors due to cold weather, rapidly dropping air pressure and mountain wave activity, which can give substantial altimeter errors.
The sheer inaccessibility of the crash site (shown above in this photo of the third peak, on the ledge slightly to the right of centre), and the danger from avalanching of the 30 to 70 foot snow pack, made removing wreckage and human remains an impossibility, and eventually the entire east side of the mountain was declared a Heritage Wreck, protected by law under the BC Heritage Conservation Act, which makes it an offence to remove any artifacts from the area. Most of the wreckage now lies in what is called the “Debris Bowl”, approximately 4,000 feet below the impact site. On the peak itself, little has changed since the wreck was found in 1957. The number 1 and 4 engines are still there, as well as most of the number 2 propeller, and enough aluminum pieces that they glint in the sun when seen from the other side of the valley. The other two engines are in the debris bowl, and hanging wreckage is still visible to mountaineers.
In the years which followed, a memorial trail was constructed which allows hikers to go from the 2,200 foot creek level up to the 5,200 foot level of the “Propeller Cairn” which contains a single propeller blade from the number 2 engine. A memorial plaque overlooks the Debris Bowl at the 4,000 foot level, and Canadian Aviation Pride members do a hike up the memorial trail each year in September.
Researching this flight over the past year has turned up over 1,100 pages of documentation from original sources, and by applying modern investigation techniques including human factors analysis, it is becoming possible to understand why this accident occurred. As might be expected in such detailed files, interesting twists are showing up, and from transcripts of unmentioned radio communications on company frequency in conjunction with the (until recently) elusive radar plot, it may soon be possible to know why ATC remained unaware of the aircraft’s real position. We have spent literally hours flying around Mount Slesse taking hundreds of photos, to capture the reality of this crash as well as the beauty of this amazing mountain landscape. A well-illustrated book will be the end result, with considerably more detail, and it is hoped that this will dispel a good deal of the mystery behind this flight.
This disaster is a milestone in Canada’s aviation history, still being the worst accident in western Canada, but it is significant in that it allows us to measure what enormous advances in aviation safety we have made in the sixty years since. Vast improvements in engine power, navigation systems, radar, communications, data recording, not to mention investigative techniques all mean that the circumstances of that evening would not result in an accident today.
The 62 people who were lost that December night are memorialized no better than by the sheer beauty of this majestic mountain which has become their resting place.
