Feb. 5, 2019 C-21 community celebrates ‘Year of the Lear’ with consolidation, avionics upgrades After 35 years of C-21 operations, mobility Airmen are celebrating 2019 as “the Year of the Lear” with upgrades for the airframe and changes within the units that fly it. The C-21 is the military version of the Lear Jet 35A.