The development of the LJ45 was announced by Bombardier in September, 1992, and first flight of the prototype aircraft took place on October 7, 1995, the 32nd anniversary of the first flight of the Learjet 23. FAA certification was delayed, and finally granted in September 1997, with the first customer aircraft subsequently delivered in January, 1998.
The cockpit is equipped with a four-screen Honeywell Primus 1000 EFIS avionics system. The aircraft is powered by two DEEC-controlled Honeywell TFE731-20 engines, a version developed specifically for this airframe. An internal APU provides ground power.
The Learjet 45XR is an upgraded version introduced in June, 2004, offering higher takeoff weights, faster cruise speeds and faster time-to-climb rates as compared to the LJ45. The increases are due to the upgrading of the engines to the TFE731-20BR configuration. LJ45 owners can upgrade their aircraft through the incorporation of several service bulletins.
In size, the LJ45 and LJ45XR fit between the smaller Learjet 31 and Learjet 40 and the larger Learjet 60 in the Lear product line. It has a 1,971-nautical-mile (3,650 km; 2,268 mi) range at Mach 0.81 with four passengers on board. De Havilland Canada builds the LJ45s wings, and Bombardier subsidiary Short Brothers of Belfast, Northern Ireland, builds the fuselage and empennage.