pilot as well as a co-pilot who doubled as the tactical coordinator (TACCO). As the RAN had a large number of highly experienced observers who had served on board Gannets, it decided to employ a single pilot and an observer who also served as the TACCO. This reduced the efficiency of the RAN's Trackers and increased the risk of accidents due to pilot fatigue. The other two members of the aircraft's crew were an observer and an air crewman. Melbourne travelled to the United States to pick up her new aircraft in late 1967, and returned to Sydney with them on 22 November that year. They were offloaded and transported by road to Mascot Airport. After receiving mechanical checks and test flights, the Trackers flew to HMAS Albatross, the Navy's air base, later that year. Melbourne commenced a refit to prepare her to operate the Skyhawks and Trackers. The Trackers were allocated to two flying squadrons. 816 Squadron was the primary operator, and flew the aircraft from Melbourne. 851 Squadron used Trackers for training purposes. 816 Squadron recommissioned with the type on 10 January 1968, followed by 851 Squadron on 2 September that year. After Melbournes refit was complete and the two squadrons had completed flight training, test flights of the S-2Es from the carrier began in March 1969. Landing was considered challenging, as there was only a gap between the Tracker's right wing and Melbournes island when aircraft landed on the right-hand side of the centreline. The trials proved successful, and the type was certified for operations from Melbourne. The RAN also acquired a Tracker Weapons Systems Trainer to support the aircraft. This system was delivered in 1967, and was initially installed in a pair of trailers; one trailer carried cockpit and instrument consoles and the other a computer, electronics and a workshop. The Tracker Weapons Systems Trainer was badly damaged by a fire started in a tea urn before it entered service, and had to be sent back to the United States for repairs. After these were complete, the system was installed in a building at HMAS Albatross. Operational service S-2E Tracker Melbournes first deployment with her new air group commenced in May 1969. During an exercise conducted in this deployment, Skyhawks flying from the carrier made a simulated attack on an "enemy" force which had first been detected by Trackers. On the night of 2–3 June 1969,