Incident at 4400N06449W

2010-02-05: DHK97, Boeing 767-300 was enroute from New York (KJFK) to East Midlands (EGNX). The estimate from Boston showed the aircraft route as BOS direct YYT. The aircraft was approximately 20 nautical miles south of course from what was received on the Boston estimate. The hard copy flight plan showed a requested flight plan route of LFV 4500N06000W YYT. When the Moncton controller inquired what route the aircraft was on, after some hesitation, the pilot advised he was proceeding 4500N06000W then YYT but would except clearance direct YYT. The controller cleared the aircraft direct YYT. After investigation with Boston and KJFK tower the aircraft had been re-cleared by the tower, BOS direct YYT and read back the clearance. The aircraft was not on the cleared route. There was no loss of separation or impact on other aircraft. Nil TSB