What happened
On a flight traveling from Key West to Naples, Florida, the aircraft with registration N21ST disappeared from radar. During the flight, a pilot operating a different aircraft observed a fireball in the area where the N21ST eventually went down. Following the aircraft's failure to reach its destination, a search operation was launched.
The wreckage of the N21ST, an unspecified aircraft type, was located the following day at 1704 EST within Everglades National Park, near Flamingo, Florida. Upon discovery, the primary wreckage was found submerged under 30 feet of mud. Investigators also located a piece of the left outboard wing, extending from the engine nacelle to the wing tip, roughly one mile away from the main debris field.
Findings
An examination of the wreckage indicated that the left wing had suffered a structural failure at the mounting point for the nacelle fuel tank and the auxiliary fuel tank boost pumps. The most significant fire damage was concentrated at the location of the left nacelle fuel tank boost pump and extended aft to the point where the rear wing spar had been consumed by flames.
While the fire was intense, investigators found no evidence of an exhaust system failure or any fuel leakage from the tanks in the vicinity of the fire. The electrical fuel boost pumps were not recovered from the site. Ultimately, the ignition source for the fire remained undetermined. The accident resulted in three fatalities.