What happened
On February 16, 2010, a Cessna C550, registration PT-WKQ, was performing a routine passenger transport flight from Ezeiza, Argentina (SAEZ), to Curitiba, Brazil (SBCT). During the flight, the co-pilot began experiencing intense fatigue and difficulty concentrating. The commander initially permitted the co-pilot to rest; however, as the aircraft approached Curitiba, the commander attempted to wake the co-pilot for the descent briefing but found him unresponsive.
Observing that the co-pilot was cold and perspiring, the commander requested priority landing and medical assistance from Curitiba Approach (APP-CT). The aircraft landed safely at Afonso Pena Airport without damage. Upon landing, the co-pilot was attended to by airport medical services, where he was treated with intravenous glucose and saline. The crew and passenger remained uninjured.
The investigation
CENIPA's investigation focused on the physiological state of the co-pilot. The investigation established that the co-pilot had recently started a restrictive, unmonitored diet three days prior to the flight, characterized by high protein and fat intake with a significant reduction in carbohydrates. Additionally, the co-pilot had been experiencing insomnia and anxiety, for which he had taken a dose of Clonazepam (a benzodiazepine) eight hours before takeoff.
The investigation noted that the co-pilot had been fasting for approximately 14 hours before the flight and had only slept four hours the previous night. The medical examination at the airport revealed that the co-pilot's symptoms improved after receiving glucose, suggesting that the combination of the medication and the diet likely induced hypoglycemia.
Findings
- The co-pilot's use of Clonazepam, a central nervous system depressant, acted as a major contributing factor due to its profound sedative effects and long half-life.
- An inadequate diet involving prolonged fasting and low carbohydrate intake depleted the body's energy reserves.
- The co-pilot suffered from fatigue resulting from insufficient sleep and the synergistic effects of medication and nutritional deficits.
- The co-pilot failed to inform the commander or the medical staff about his use of the contraindicated medication.