Incident at EDMONTON CITY CENTRE / BLATCHFORD AB (CYXD) (Flight instrument failure, Electrical problem, Conflict - loss of separation, Alleged Canadian Aviation Regulations (CARs) infraction)


2001-07-18: TSB reported that WJA 80 was operating a flight from Ft. McMurray to Edmonton and the B737-200 was climbing through 10,000 feet when the number one air data computer failed. This in turn caused the following systems to become inactive: Captain's altimeter, GPWS, Mach trim, Mode C transponder, and altitude alerter. ATC was advised of the situation and control was given to the First Officer, whose altimeter was functioning off the number two air data computer. On descent from 35,000 feet to 23,000 feet, WJA 80 was cleared for deviations west for thunderstorms. Outbound from the Edmonton City Centre airport was an Air Tindi Beech King Air 200 climbing to 22,000 feet direct to Yellowknife, NT. Without Mode C, the altitude read out for WJA 80 was not available for the controller's radar display. The Controller passed traffic to the King Air crew and shortly after, they reported the visual passage of WJA 80 to the Controller as being at their altitude, descending, and 2-3 NM off their right side. The WJA 80 flight crew descended through 22,000 feet before realizing that they had missed the level off at 23,000 feet. Required separation minima for this airspace was 1,000 feet vertically or 5 NM horizontally. Maintenance in Edmonton replaced the number one air data computer and the aircraft was returned to service.
2001-07-16: C-FCGU, a Beech King Air, was on a flight from Edmonton City Centre Airport (YXD) to Yellowknife, ascending to FL 220. WJA 80 was on a flight from Fort McMurray J517 to Edmonton International Airport(YEG) with clearance to descend to FL 230. WJA 80's mode C altitude readout was not being received by the Controller. At 1553Z, it was reported that WJA 80 had descended below FL 230 without clearance and had passed below C-FCGU with approximately 2 NM lateral separation between the aircraft. In this airspace either 1,000 feet vertical or 5 NM lateral separation is required. It was later reported that the number 1 air data computer in the B737 had failed and the Captain's side flight instruments had failed as a result. TSB continues to follow up with the company.


CADORS Number 2001C0810
Occurrence Type Incident
Reported By NAV CANADA
Occurred At 2001-07-13 - 15:53
Day or Night? Day-time
Fatalities 0
Aerodrome ID CYXD
Geographic Location Alberta, Canada, North America, Prairie and Northern Region, Vicinity of Edmonton
TSB Occurrence Number A01W0168
TSB Class of Investigation Class 5
AOR Number 16379
Reported By NAV CANADA
Categories System/component failure or malfunction [non-powerplant],Other,Airprox/TCAS alert/loss of separation/(near) midair collisions
Events Flight instrument failure,Electrical problem,Conflict - loss of separation,Alleged Canadian Aviation Regulations (CARs) infraction

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