The non-instrument-rated pilot, copilot, and a passenger were flying in a Cessna 310 from the Bahamas to Florida. A weather front was passing over Florida at the time.
The copilot contacted flight service before the initial flight and learned of thunderstorms in the area and the flight had to divert from its planned destination.
The copilot contacted flight service before a second flight, and the flight service specialist advised that visual flight rules flight was not recommended due to low cloud ceilings and visibility.
The pilot decided to land at an airport closer to his destination. At that airport, the copilot again contacted flight service and remarked that he was trying to figure out how to “scud run” to get home.
He also spoke to his wife, who told him that the weather “was bad” at their final destination, and she reported that she thought they would delay their flight until the next day.
About 20 minutes into the last leg of the flight, the copilot contacted the Orlando approach controller and reported that they had inadvertently entered instrument meteorological conditions (IMC).
The controller instructed him to set the transponder code to 0311 so that she could locate the airplane and then to contact Miami Center, however no further communications were received from the copilot.
Review of radar data revealed that, shortly after contacting Orlando, while the controller was attempting to locate the airplane, it descended in three left turns from 8,900 feet MSL to 1,800 feet MSL, then turned right descending to 900 feet MSL, and continued to proceed toward the destination airport.
The last three minutes of radar data showed the airplane flying at an altitude between 100 and 200 feet MSL. The final radar target was recorded while the airplane was in a left turn at 200 feet, about 1/8 mile southwest of the accident site.
The wreckage was located the following day in a heavily wooded, deep water, swamp area near Yeehaw Junction, Fla., and no debris path was observed.
Given the radar data and the existence of marginal visual conditions, moderate rain, and the pilot not being instrument rated, it is likely that the pilot experienced spatial disorientation.
Two toxicological tests revealed measurements of diphenhydramine in the pilot’s blood at levels within or well above the therapeutic range, indicating that the pilot likely took the drug about two to three hours before the accident. Diphenhydramine causes marked sedation and is also classed as a depressant and used as a sleep aid. Altered mood and impaired cognitive and psychomotor performance may also be observed.
Therefore, it is very likely that cognitive and psychomotor impairment caused by diphenhydramine contributed to the pilot’s poor judgment about flying in marginal weather conditions and may have further impaired his ability to cope with relatively unfamiliar flying conditions when he flew into IMC.
The NTSB determined the probable causes were the pilot’s improper decision to continue visual flight rules flight into instrument meteorological conditions and his subsequent spatial disorientation.
Contributing to the accident was the copilot’s improper evaluation of the weather conditions after receiving several weather briefings for the flight.
Also contributing to the accident was the PIC’s cognitive and psychomotor impairment due to recent use of an over the counter sedating antihistamine and the pilots’ personal pressure to get home.
NTSB Identification: ERA13FA133
This February 2013 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.