At about 8 a.m. on October 30, 1985, Grant was killed in an automobile accident west of Titusville in Brevard County, Florida. Three vehicles were traveling east bound in single file, Grant was in the third vehicle. He pulled out of line (to the left) to pass both vehicles in front of him, when the middle vehicle also pulled out to pass at the same time. To avoid a collision, Grant suddenly swerved farther left, and went onto the shoulder of the oncoming lane, he then over-corrected back all the way to the right, when his vehicle left the roadway and spun into a ditch, which contained three feet of standing water. Grant was thrown out of his car and into the water. A passerby pulled him out, and he was taken to Jess Parrish Hospital in Titusville, but was dead on arrival. That morning, Grant was en route from his condominium in Winter Springs to the Kennedy Space Center to watch the (last successful) launch of the Space Shuttle "Challenger" at Cape Canaveral. He was to have been honored by the astronauts for encouraging aviation and space flight. He was 73 years old. Kirby is interred in Missoula, Montana.