Accident Boeing 707-321C CF-PWZ,

ASN Wikibase Occurrence # 330286

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Date:	Tuesday 2 January 1973
Time:	01:34
Type:	Boeing 707-321C
Owner/operator:	Pacific Western Airlines
Registration:	CF-PWZ
MSN:	18826/389
Year of manufacture:	1964
Total airframe hrs:	33059 hours
Cycles:	9458 flights
Engine model:	Pratt & Whitney JT3D-3B
Fatalities:	Fatalities: 5 / Occupants: 5
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	ca 3 km SE of Edmonton International Airport, AB (YEG) - Canada
Phase:	Approach
Nature:	Cargo
Departure airport:	Toronto International Airport, ON (YYZ/CYYZ)
Destination airport:	Edmonton International Airport, AB (YEG/CYEG)
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
On the ground at Toronto cattle pens were installed and a cargo of 86 cattle was loaded. The Boeing 707 took off at 04:47 GMT for a flight to Edmonton. The en route part of the flight was uneventful. At 08:29 the flight was cleared for a straight in back-course ILS approach to runway 29. The first officer, who had just been promoted to Boeing 707 operations, was to perform the approach in blowing snow conditions. This approach was the first one after a 6-week holiday, so he lacked recent Boeing 707-experience. With the added factors of fatigue, turbulent air, and a heavily loaded aircraft the situation would have become extremely difficult. At some point late in the approach the captain took over control of the aircraft and tried to arrest the sink rate. The plane contacted poplar trees, 3137 m short of the runway. It struck the ground a glancing blow, and the tail fin struck powerlines. The aircraft finally struck a large ridge in the middle of a gravel pit. The cockpit section and a forward portion of the fuselage broke away and 86 cattle, the cargo on board, shot forward through the open front section of the fuselage and were thrown a distance of up to 100 m. A fire erupted.

Summary
The combination of circumstances leading to this accident were such that the margins of operating safety were seriously compromised by the time the aircraft entered the final stages of its approach which was being made in difficult weather conditions and without glidslope guidance to the runway in use.
The flight crew members being fatigued, would have found it difficult to concentrate fully on the task at hand without any added difficulty of having their attention diverted by some untoward event.
This probably applied particularly in the case of the Captain whose primary function at this stage of the flight was to closely monitor the First Officer's handling of the aircraft. However, if an interruption to the essential electrical system had occurred he probably would have divided his attention between monitoring the First Officer's and the Flight Engineer's activities.
And so, at the most vital stage of the approach, the First Officer, inexperienced as he was wlth the aircraft type and its equipment, may have been left to cope with the approach which was probably beyond his capabilities. With the added factors of fatigue, turbulent air, and a heavily loaded aircraft the situation would have become extremely difficult.
In these circumstances, if the Captain's attention had been momentarily distracted, control of the aircraft would have been jeopardized at an altitude too low to effect recovery.

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photo (c) Vic Normandeau; Edmonton International Airport, AB (YEG); 19 May 1973