History of Flight
On June 3, 2022, about 1347 Pacific daylight time, a Cessna 208B modified as a Supervan Systems LLC 900 airplane, registration N7581F, was substantially damaged when it impacted terrain near Bob Maxwell Memorial Airfield in Oceanside, California. The left-seated pilot sustained fatal injuries, and the right-seated pilot sustained serious injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a skydiving operation.
The pilots had completed six previous skydiving flights that day without incident. Each flight involved carrying about 17 skydivers to approximately 11,500 feet mean sea level. The accident flight departed at 1331. According to the right-seated pilot, the departure and skydiver drop were normal. During descent with power at idle, as the airplane turned onto final approach about 2–3 miles from runway 25, the left-seated pilot reached for the throttle. The right-seated pilot, sensing the airplane was low, attempted to increase power but found the throttle unresponsive. He estimated the altitude at 400 feet above ground level, aimed for an open dirt field, and maneuvered to avoid a berm.
ADS-B data showed the airplane climbing to 11,575 feet, then descending steeply. On final approach, it executed a tight 360° turn. The last recorded data point at 1347:10 indicated 190 feet agl and 68 knots ground speed. Witnesses observed the airplane flying low, then pitching nose-down and banking right before impacting terrain and a berm. Security camera footage captured the airplane seconds before impact.
Personnel Information
The right-seated pilot, employed by Desert Sand Aircraft Leasing Co., had over 20 years of experience and was training the left-seated pilot. The left-seated pilot had six days and 25.8 hours of experience in the modified Cessna 208, all in the left seat during the previous three days. She was listening to music at 79 decibels through her headset during the accident flight, which prioritizes intercom communications.
Aircraft Information
The airplane was modified in 2012 with a TPE331 engine and 4-blade propeller under Supplemental Type Certificate SA10841SC. The engine is controlled by a power lever (black) and speed lever (blue) in the cockpit center console.
Wreckage and Impact Information
The wreckage was located 1,615 feet east of runway 25 on soft, dry dirt, scattered over 125 feet. The right wing was partially separated and folded. Flight control continuity was established. The engine was rotating at impact with no evidence of pre-existing mechanical malfunction. Approximately 50 gallons of Jet A fuel were recovered from the right wing; the left wing fuel line had separated. The left seat belts were found unbuckled; the right-seated pilot wore only a lap belt.
Medical and Pathological Information
Toxicology testing detected ketamine in the left-seated pilot's cavity blood and liver, consistent with post-accident resuscitation efforts. First responders found both pilots unresponsive; the right-seated pilot was found partially through the left window.
Tests and Research
A performance study by the NTSB Vehicle Performance division compared thrust coefficients of the accident descent to previous flights. Results showed similar negative thrust coefficients, except for oscillations in the final 50 seconds. The cause of the thrust oscillations was undetermined but may have been due to power lever manipulation. The throttle quadrant response is sensitive near the transition between propeller-governing and underspeed-governing modes, where small movements cause large thrust changes. A Texas Turbine representative noted that such oscillations can occur when pilots unfamiliar with the engine make rapid, large power lever inputs.