On April 18, 2011, at 1930 central daylight time, an Air Tractor AT-802A, N802KC, and an Air Tractor AT-502B, N8516K, were involved in a midair collision while both airplanes were engaged in aerial application operations near New Madrid, Missouri. The commercial pilot flying the AT-802A suffered serious injuries and the commercial pilot flying the AT-502B was not injured. Both airplanes were being operated by Hampton Flying Services LLC under 14 Code of Federal Regulations Part 137. Visual meteorological conditions prevailed and neither airplane was operating under a flight plan. The AT-802A came to rest in a farm field after the collision and the pilot of AT-502B was able to land his airplane at the County Memorial Airport (EIW), New Madrid, Missouri. The pilot of the AT-802A does not recall the events surrounding the accident. The pilot of the AT-502B reported that he departed runway 18 and made a left turn to a northeasterly heading. He reported that the airplanes collided head-on at an altitude of 500 feet above the ground. Inspection of the airplanes and accident site by a Federal Aviation Administration inspector revealed the collision occurred about 2 1/2 miles north of EIW. The AT-502B was had just taken off and was full of chemical. The AT-802A was returning from spraying and no chemicals were on board. The AT-802A was on a southwesterly prior to the collision. After the collision the airplane cleared a 5 foot tall fence prior to contacting the terrain. The airplane then traveled about 150 feet prior to coming to rest. The AT-502B was on a northeasterly heading. The pilot of the AT-502B was able to return to the departure airport where he landed. Impact marks and the location of the wreckage indicated the spray boom on the AT-502B contacted the windshield on the AT-802A. The right wheel on the AT-502B contacted the left side of the vertical stabilizer on the AT-802A. Both the right main gear and the vertical stabilizer were located in a field near the collision site. The horizontal stabilizer remained attached to the AT-802A. There was no known communication between the airplanes.