HISTORY OF FLIGHTOn March 8, 2015, around 1650 central daylight time, N7698S, a Bellanca Decathlon 8KCAB, single-engine airplane, impacted terrain shortly after it made a low pass over a small private lake near Kosciusko, Mississippi. The private pilot and the pilot rated passenger were fatally injured. The airplane was registered to and operated by a private individual. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight that departed the Kosciusko-Attala County Airport (OSX) at an undetermined time and was conducted under the provisions of 14 Code of Federal Regulations Part 91. Several witnesses observed the airplane flying over a private airstrip that was adjacent to a small lake. The witnesses were on the beach of the lake and the pilot knew the landowner. According to one witness, he said the airplane initially made a high pass over the airstrip. The airplane then returned, but this time it was a lot lower and it "buzzed" the lake. The pilot pulled the airplane straight up to clear a stand of 50-foot–tall pine trees, when it suddenly nosed over and dropped straight down into the ground on the opposite side of the tree line. The witness said the airplane and engine were operating normally and the pilot was "just having fun." When the airplane passed over the lake, the pilot was grinning from "ear to ear" and the passenger was waving out of the window. The witness said it wasn't windy or raining at the time of the accident. Another witness was a retired airline pilot and active aerobatic pilot on the airshow circuit. He owned the land the airplane had flown over and knew the pilot well. The witness said the pilot flew over the lake on a south-westerly heading but did not recall the airplane's altitude. He could see the pilot in the cockpit and he was smiling. The airplane then began a climbing right turn. As the airplane turned through 90-degrees, the left wing dropped. The witness said the pilot tried to recover from the "cross-control stall", by lowering the nose of the airplane and making a full deflection of the rudder control. The airplane leveled out momentarily before it suddenly nosed-over. At the same time, the witness heard the engine power go to full throttle before it impacted the ground. The witness said the airplane did not have the altitude to recover and did not spin before it hit the ground. PERSONNEL INFORMATIONThe pilot held a private pilot certificate for airplane single-engine land. His most recent Federal Aviation Administration (FAA) Third Class medical was issued on April 21, 2014. At that time, he reported a total of 1,614.5 flight hours, of which, 31.6 hours were in the previous six months. The pilot rated passenger held a private pilot certificate for airplane single-engine land. His most recent FAA Third Class medical was issued on May 1, 2013. At that time, he reported a total of 136 flight hours, of which, 70 hours were in the previous six months. AIRCRAFT INFORMATIONThe Bellanca Decathlon KCAB is a two-seat, fixed-gear airplane that was designed for flight training and personal use and is capable of sustaining aerobatic stresses between +6g and -5g. The airplane's most recent annual inspection was completed on April 27, 2014, at a total time of 1,775.0 hours. METEOROLOGICAL INFORMATIONWeather reported at Greenwood-Leflore Airport (GWO), Greenwood, Mississippi, about 37 miles northwest of the accident site, at 1653, was reported as wind from 010 degrees at 5 knots, visibility 6 miles, light rain, mist, ceiling 600 overcast, temperature 9 degrees Celsius, dewpoint 7 degrees Celsius, and a barometric pressure setting of 30.24 inches of Hg. AIRPORT INFORMATIONThe Bellanca Decathlon KCAB is a two-seat, fixed-gear airplane that was designed for flight training and personal use and is capable of sustaining aerobatic stresses between +6g and -5g. The airplane's most recent annual inspection was completed on April 27, 2014, at a total time of 1,775.0 hours. WRECKAGE AND IMPACT INFORMATIONA postaccident examination of the airplane was conducted the day after the accident. The airplane was pointed nose down with the tail almost vertical in the air. The engine was partially buried in the soft ground about 1-2 feet. Both wings exhibited leading edge impact damage, and the wood spars and ribs were fractured. Flight control continuity was established for the ailerons to the wing root. The cockpit area was crushed. The empennage and tail section were intact. The outboard section of the left horizontal stabilizer exhibited minor damage. Flight control continuity for the elevators and rudder was established to the aft cockpit area. A review of photographs taken of the engine and propeller after of the airplane was recovered revealed no obvious mechanical problems that would have precluded normal operation of the engine. The two-bladed propeller remained attached to the engine and the spinner was twisted and crushed. One blade was bent aft and the second blade was bent aft at the tip. MEDICAL AND PATHOLOGICAL INFORMATIONToxicological testing was completed on both the pilot and the pilot-rated passenger by the FAA's Toxicological laboratory in Oklahoma City, Oklahoma. The pilot tested negative for all items tested. The pilot rated passenger tested positive for Diphenhydramine, which was detected in his Urine and 0.032 (ug/ml, ug/g) Diphenhydramine was detected in his blood (Cavity). Autopsies were completed on the pilot and pilot rated passenger by the Mississippi Medical State Medical Examiner, Jackson, Mississippi. The cause of death for both the pilot and the pilot rated passenger was blunt force trauma.