Incident
at 60 NM E of Winnipeg, MB
KUGR 27, a CF-18, enroute to Winnipeg (YWG) via Thunder Bay (YQT) direct YWG at FL 390 was initially cleared to descend to FL 310. BLS 399, a Pilatus PC-12, enroute to YWG via YQT direct YWG at FL 240 was cleared to maintain 7,000 feet. KUGR 27 was subsequently cleared to maintain FL 240 and given traffic below him leaving FL 230. The pilot of KUGR 27 read back "cleared to FL 240." At 2253Z, when 60 miles east of YWG, KUGR 27 was observed on radar descending below FL 240. When the Controller queried the pilot, he said that he was cleared to FL 210. At that time, KUGR 27 was 8 miles ahead of the traffic and was cleared to maintain 7,000 feet. OPI - Enforcement