only a pilot, for example the F-15E Strike Eagle is a development of the F-15D which is a two-seat training version of the F-15 Eagle. In some air forces that have a mix of high- and low-performance aircraft, pilots can be first be assigned to aircraft with a lower level of performance before moving on to the most demanding aircraft. For example, in the Italian Air Force a pilot may begin his service career on the AMX attack aircraft, and as their experience grows, progress to more capable aircraft such as the Tornado IDS. Other air forces, such as Canada, do not do this, and assign first-tour pilots to aircraft such as the CF-18 Hornet. Multi-engine trainers Those pilots who train to fly transports, tankers and other multi-engine aircraft begin with small multi-engine aircraft such as the T-44A Pegasus variant of the Beechcraft King Air. Once they have mastered this, they may begin to fly in the right-hand seat of an operational type. Some air forces will seek to use a restricted number of multi-engined aircraft, with the derivatives of a basic aircraft filling different roles so that a pilot qualified on one of its types can easily convert to others in the same family. For example, the Boeing 707 was a popular airliner for conversion to tanker, transport and ELINT variants by numerous air forces. Navigation trainers A minority of military training aircraft, such as the Beechcraft 18, Vickers Varsity, Hawker Siddeley Dominie and Boeing T-43 were developed from transport designs to train navigators and other rear crews operators. As these navigational trainees are normally learning how to navigate using instruments, they can be seated at consoles within the aircraft cabin and do not require a direct view of the landscape over which the aircraft is flying. The operators of airborne weapons or radar-related systems can be similarly trained, either in training aircraft or in an operational aircraft during training flights. Aerobatic display teams Some jet trainers, such as the Aermacchi MB-339, Casa C-101, Folland Gnat, Fouga Magister and British Aerospace Hawk, are used by national formation aerobatic teams. Early jet aerobatic teams tended to use combat types such as the Hawker Hunter, English Electric Lightning, and North American F-100 Super Sabre. As air forces' combat fleets were scaled-down, it made sense for most national display teams to change to lighter training types. A few modifications may be needed