During a recon flight, Heater suggested that they should examine one of the fetus fields. Both Mac and Split thought it was too high of a risk, but Heater suggested that by using the dumping grounds as cover, they could avoid detection by the Machines. Eventually they agreed to his plan and headed toward the fields.
As they flew low to the ground, using the dumping grounds as cover, something on the surface clipped their ship and ruptured the starboard input tank, causing the ship to crash. Mac was able to survive the crash, but Heater and Split died on impact.