The NTSB determined that a July 2007 accident in Sanford, Fla., which killed the two aboard the airplane and three people on the ground, was caused by a series of poor decisions by flight department management and the pilots who flew the accident aircraft. The Cessna 310R, operated by Nascar's aviation division, crashed after the pilot reported an in-flight fire. The accident was due to Nascar’s allowing the airplane to be released for flight with a known and unresolved electrical system problem and the accident pilot’s decision to operate the airplane with full knowledge of the maintenance discrepancy, according to the NTSB. For maintainers, the NTSB recommended that initial and recurrent training of maintenance personnel working on general aviation aircraft include best practices regarding the inspection and maintenance of electrical systems, circuit breakers and wiring. The NTSB also recommended that manufacturers and those responsible for post-manufacture modifications improve guidance or create new guidelines regarding which circuit breakers pilots should and should not attempt to reset before or during flight.