However, as pilots pull on the 737 controls to raise the nose of the aircraft, aerodynamic forces on the elevator create an opposing force, effectively paralyzing the jackscrew mechanism that moves the stabilizer.[97] It becomes very difficult for pilots to hand crank the trim wheel.[97] The problem was encountered on earlier 737 versions, and a "roller coaster" emergency technique for handling the flight condition was documented in 1982 for the 737-200 but did not appear in training documentation for later versions (including the MAX).[97]