Learjet 60Gates Bombardier Learjet 60 airplane model. The improved Learjet 60 first flew in its basic definitive form in June 1991 (the modified Learjet 55 prototype earlier served as a proof of concept aircraft for the 60 with Garrett engines). It differs from the 55 in having a 1. 09m (43in) fuselage stretch and new Pratt &, Whitney Canada PW305 turbofans. Certification of the 60 was awarded in January 1993, with first deliveries following shortly afterwards.