Incident at CALGARY INTL AB (CYYC) (Conflict - loss of separation, Alleged Canadian Aviation Regulations (CARs) infraction)


2003-06-02: UPDATE TSB reported that the Westjet Airlines Boeing 737-200, C-GIWJ, was operating as WJA 46 from Edmonton, AB to Calgary, AB. The En Route Controller issued a clearance to descend from FL 250 to 16,000 feet. The clearance was received and read back correctly by WJA 46. A loss of separation occurred when WJA 46 continued the descent through 16,000 feet in the vicinity of an Air Canada Jazz Dash 8-100 which was level at 15,000 feet. The Controller advised WJA 46 of their assigned altitude and they arrested the descent at 15,600 feet and climbed to 16,000 feet. Separation was reduced to 3.5 NM and 600 feet where 5.0 NM or 1,000 feet is required.
2003-05-30: JZA 8319, a DHC-8 en route from Edmonton (YEG) to Calgary (YYC), was TORON at 2203Z, 15,000 feet with clearance to descend to 12,000 feet. WJA 46, a B737 also en route YEG - YYC, was TORON at 2205Z, at FL 250 with clearance to descend to 16,000 feet. The Controller passed JZA 8319 traffic to the crew of WJA 46 and subsequently observed WJA 46 descending through 15,600 feet and confirmed with the crew that they were stopping at 16,000 feet. They replied that they read back 12,000 feet and that they were now in the climb. A review of the audio tapes indicated that WJA 46 was issued 16,000 feet and read back 16,000 feet. Separation between the two a/c was reduced to 3.5 NM in an area where 5.0 NM is required. An operating irregularity did occur as a result of the pilot not complying with the clearance.


CADORS Number 2003C0666
Occurrence Type Incident
Reported By NAV CANADA
Occurred At 2003-05-29 - 22:08
Day or Night? Day-time
Fatalities 0
Aerodrome ID CYYC
Geographic Location Alberta, Canada, North America, Prairie and Northern Region, 40 NM N of Calgary
TSB Occurrence Number A03W0104
TSB Class of Investigation Class 5
AOR Number 29517
Reported By NAV CANADA
Categories Other,Airprox/TCAS alert/loss of separation/(near) midair collisions
Events Conflict - loss of separation,Alleged Canadian Aviation Regulations (CARs) infraction

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