Incident
at MONTRÉAL / PIERRE ELLIOTT TRUDEAU INTL QC (CYUL)
A Porter Airlines de Havilland DHC-8-402 (POE471) from Toronto/Billy Bishop, ON (CYTZ) to Montreal/Pierre Elliott Trudeau, QC (CYUL) was in a holding pattern at ARVIE and FL200, and at 1912Z, it was cleared for descent. POE471 was seen at FL203 before starting to descend. A WestJet Encore de Havilland DHC-8-402 (WEN3526) from Toronto/Lester B. Pearson, ON (CYYZ) to Montreal/Pierre Elliott Trudeau, QC (CYUL) was also in the holding pattern at ARVIE and FL200. For a few seconds, separation was reduced to 700 ft and 3,3 NM, where normally, separation must be 1 000 ft or 5 NM.
Update: TSB Report #A19Q0027: C-GLQZ, a Porter Airlines Bombardier DHC-8-400, was on flight POE471 from Toronto/Billy Bishop Toronto City, ON (CYTZ) to Montreal/Pierre Elliott Trudeau Intl, QC (CYUL). During the descent at CYUL, air traffic control (ATC) assigned POE471 to a holding pattern at ARVIE, at FL200. C-GENM, a WestJet Encore Bombardier DHC-8-400, was on flight WEN3526 from Toronto/Lester B. Pearson Intl, ON (CYYZ) to CYUL, and was also in the holding pattern at ARVIE, FL210. When POE471 was cleared to leave the holding pattern, it was seen at FL203, which caused a loss of separation with WEN3526. Separation was reduced to 700 ft vertically and 3.3 NM laterally, while the standard was 1 000 ft or 5 NM.