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


2005-02-11: CNK505 was cleared to 13,000 feet due to traffic ahead, NCB099. CNK505 took a clearance to 8000 feet issued to PE557 and continued descent. CNK505's readback of the descent to 8000 feet was not received; it likely came in the form of an squeal on the frequency during the time that PE557 read back its clearance. The controller noticed the deviation when CNK505 was through 10,800 descending and NCB099 was through 10,200 descending to 10,000. The controller took remedial action by clearing NCB099 to 8000 and CNK505 to 11,000 feet. At closest proximity, there was 600 feet vertical and 1.5 mile lateral spacing where 1000 feet and 3 miles are required. CNK505 was TCAS equipped but it was inoperable. Calgary METAR 0300 23011KT 15SM FEW120 BKN220 04/M08 *2989*
2005-02-18: UPDATE TSB reported that the Sunwest Home Aviation Cessna Citation 550, registration C-GAPV, operating as CNK 505, was inbound to Calgary and had been cleared to descend to and maintain 13,000 feet, due to traffic ahead. The traffic was a North Caribou Beech King Air 100, registration C-GBVX, operating as NCB 099, also inbound to Calgary. When ATC issued a clearance to a third aircraft, a Beech King Air 100 operating as Peace Air PE 557, to descend to 8000 feet, CNK 505 responded to and complied with the clearance and continued the descent below 13,000 feet. CNK 505's readback of the clearance to 8,000 feet occurred at the same time as PE 557's readback of the clearance. ATC did not receive the CNK 505 readback; however, there was a squeal on the frequency during the PE 557 transmission, indicating that the CNK 505 transmission was blocked. The Controller observed the deviation when CNK 505 was descending through 10,800 feet and NCB 099 was descending through 10,200, to 10,000 feet. The Controller immediately cleared NCB 099 to 8,000 feet and CNK 505 to 11,000 feet. Separation was reduced to 600 feet vertical and 1.5 miles lateral where 1,000 feet and 3 miles were required. CNK 505 was TCAS equipped; however, the system was inoperative at the time of the occurrence.


CADORS Number 2005C0324
Occurrence Type Incident
Reported By NAV CANADA
Occurred At 2005-02-11 - 02:50
Day or Night? Day-time
Fatalities 0
Injuries 0
Aerodrome ID CYYC
Geographic Location Alberta, Canada, North America, Prairie and Northern Region, 30 NM NW of Calgary
TSB Occurrence Number A05W0028
TSB Class of Investigation Class 5
AOR Number 53516- V2
Reported By NAV CANADA
Categories Other,Airprox/TCAS alert/loss of separation/(near) midair collisions,ATM/CNS
Events Conflict - loss of separation,Communication error,Alleged Canadian Aviation Regulations (CARs) infraction

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