What happened
On November 27, 2000, a Finnair scheduled flight, AY657, operating a Douglas DC-9-83 (MD-83), departed Helsinki for Oslo. Approximately 35 minutes into the flight, while cruising at FL350, the first officer began experiencing significant physical distress. The crew had been eating a meal when the first officer reported feeling faint and requested supplemental oxygen.
As the first officer's condition deteriorated, the captain observed a significant decline in the crew member's level of consciousness. To ensure safety, the captain decided to terminate the flight to Oslo and divert to Stockholm Arlanda, which served as the nearest suitable airport with favorable weather conditions. During the diversion, the first officer was moved to the cabin to rest, and a Finnair training captain, who was a passenger on the flight, joined the cockpit to assist with flight duties.
The investigation
The investigation examined the medical history of the crew, radio communications, and the aircraft's operational procedures. Investigators reviewed the first officer's recent health, noting he had experienced gastrointestinal issues for approximately one month. Medical examinations later revealed that the first officer suffered from lactose intolerance. Additionally, the investigation looked into the crew's use of medication and the captain's decision-making process during the emergency.
Findings
- The first officer had been using medications for skin conditions that he had not discussed with the airline's aviation medical examiner.
- The primary cause of the incapacitation was likely a transient gastrointestinal disturbance, potentially exacerbated by lactose intolerance and the side effects of his prescribed chemotherapy medication.
- The captain and cabin crew acted professionally and in accordance with company procedures regarding crew incapacitation.
- The investigation noted that the captain did not ensure the preservation of the cockpit voice recorder (CVR) for the investigation, as he did not initially categorize the event as a serious incident requiring such specific preservation steps.
Safety action
- Finnair should enhance ground training for flight crews, emphasizing the necessity of consulting the company aviation medical examiner before starting or resuming flight duties when considering new medications or when prescribed medication is received from an external physician.
- The airline should encourage crews to seek medical evaluation through the company's medical examiner if they suspect symptoms related to lactose intolerance.
- Finnair should update its operations manual (OM-A) to ensure the definition of "serious incidents" aligns with regulatory requirements for the preservation of flight recorders.