After departing Essendon the aircraft climbed, as cleared by air traffic control, to cruise altitude 9,500 feet. A radar return and label were observed by the Sector 3 Radar Controller in the vicinity of Cowes, on the basis of which a Sartime for clearance to cross controlled airspace at Devonport was calculated. At or about the Sartime, Sector 3 contacted Flight Service 15 to ascertain if the aircraft was listening out on 120.7 (Area frequency). Contact was subsequently established with VH-PZP on 123.8 (Melbourne Control) and the pilot reported his position as 7 nautical miles (by Distance Measuring Equipment) south of Devonport. The aircraft had passed through the north western tip of Launceston controlled airspace without a clearance. No breakdown in separation occurred. This flight was the pilot's second charter flight. He was unfamiliar with the area. Because this was his first Bass Strait crossing and because he did not hold an instrument rating he co-opted the assistance of another commercial pilot, who holds a current instrument rating, to act as the safety pilot. When he was flight planning, the pilot-in-command did not notice that the route would infringe controlled airspace. The safety pilot subsequently did not detect the penetration.