Incident at near the Aylmer VOR (Other operational incident, Conflict - potential, Conflict - loss of separation, ATS operating irregularity)

1996-06-12: C-FNGA, inbound to Toronto City Centre Airport, was over the Aylmer (ON) VOR when it was given a descent to 10,000 feet. There was a problem at Toronto City Centre with weather limits and C-FNGA was advised of 30 minute delays into Toronto (LBPIA) due to weather. The controller intended on forcing N208R inbound to Toronto Buttonville from over Buffalo below C-FNGA but forgot to stop C-FNGA's descent. Ops. impact -- unknown. Supplemental information from T.S.B. Initial Notification (#A96O0100): C-FNGA, a Piaggio P-180 Avanti, was en-route from Chatham Airport (CNZ3) to Toronto (City Centre) Airport (CYTZ). Weather at the Toronto (City Centre) Airport was below limits. This information was passed to the flight crew of C-FNGA as they were given descent clearance to 10,000 feet in the vicinity of the Aylmer VOR. The flight crew of C-FNGA were also informed that there would be a delay getting into Toronto (LBPIA) (CYYZ). At the same time, a Hawker Siddley 125-100 (N208R) was en-route from Buffalo (Greater Buffalo) International Airport, NY (U.S.A.) (KBUF) to Kitchener-Waterloo Regional Airport (CYKF) and was given descent clearance to 10,000 feet. It was the controller's intention to restrict C-FNGA's descent to ensure the two aircraft crossed with adequate spacing. The controller anticipated the flight crew of C-FNGA would be requesting an approach for Toronto (LBPIA). While waiting for the request, the controller forgot to restrict C-FNGA's descent. The Hawker Siddley 125 passed three (3) miles behind and 500 feet lower than C-FNGA. The controller was working an extended shift due to limited staff availability. Neither flight crew was aware of the technical loss of separation. S.O.B.: C-FNGA: 11 -- two (2) crew; nine (9) passengers; and N208R: eight (8) -- two (2) crew; six (6) passengers.