General Aviation News will often reprint accident reports from the USA’s National Transportation Safety Board (NTSB), including one dated September 2010 that involved a Cessna 182 in Helena (Georgia) where there was one fatality due to fog and possibly undiagnosed diabetes.
The pilot was both a CFI and a commercial pilot with 14,600 hours while his wife estimated that he had roughly 150 hours in the Cessna 182. There was also a private pilot-rated passenger with 200 flight hours (but no instrument rating).
The Cessna 182 was heading to an airport that lacked a control tower and weather reporting facilities, but it did have a GPS approach. After checking the weather at nearby airports, the pilot told ATC that he would need to fly a GPS approach. He was cleared for the approach and there was no further communication with the pilot.
Radar showed that after the pilot intercepted the final approach segment, he descended without leveling off at the minimum descent altitude only to crash 2.74 miles from the runway – on both a course and a heading that were aligned with the runway. Although the weather at the airport was foggy, it was gradually improving at the time of the accident while the surviving passenger had no recollection of what happened.
However, an autopsy of the pilot revealed “elevated glucose levels in the vitreous fluid and urine, and an elevated hemoglobin A1c level in the blood.” In other words, he was likely a diabetic with poorly-controlled blood sugar.
The pilot’s wife also indicated that he had eaten breakfast that morning and there was no evidence that he was even aware of being diabetic. And while the autopsy and investigation could not determine whether the pilot was impaired, his blood sugar levels could have been high enough to impact his cognitive performance – contributing to a crash in foggy conditions.
Given the above incident, its probably a good idea to at least have at least an annual physical if you fly regularly as you never know whether an undiagnosed or underlying medical condition could impact your ability to fly in adverse flying conditions.