What happened
On 2 February 2012, a scheduled commercial flight operated by Malmö Aviation departed from Stockholm/Bromma Airport bound for Malmö/Sturup. The aircraft, a British Aerospace Avro-146-RJ100 with registration SE-DSX, was operating in nighttime conditions with recent snow clearance activities at the airport.
Approximately five minutes into the climb, at an altitude of roughly 5,000 feet, the commander experienced a sudden onset of severe dizziness, nausea, and tunnel vision. Due to this physical impairment, the commander handed control of the aircraft to the co-pilot. To ensure safety, the crew decided to abort the climb and return to Bromma. During the flight, the commander' and the co-pilot's roles were split, with the co-pilot managing both flying duties and radio communications. To avoid causing passenger concern, the crew initially informed the passengers that the return was due to a minor technical fault, though the cabin crew was aware of the pilot's medical condition.
The investigation
The Swedish Accident Investigation Authority (SHK) investigated the incident, specifically looking into whether cabin air contamination from engine oil could have caused the symptoms. The investigation examined the possibility of exposure to triorthocresyl phosphate (ToCP), a neurotoxic substance found in certain jet engine oils that can form aerosols during leaks.
Medical examinations and blood tests were conducted on the commander. The investigation also reviewed the operator's procedures regarding crew incapacitation and their protocols for handling suspected air contamination. The SHK examined the aircraft's maintenance records and oil consumption levels to determine if any leakage had occurred.
Findings
- The primary cause of the incident was a temporary illness affecting the commander.
- There was no evidence of technical faults or engine oil leaks that could have contaminated the cabin air.
- The symptoms experienced by the commander—including blacking out and nausea—were not observed in any other crew members.
- While the co-pilot followed many established procedures, no emergency message was transmitted to air traffic control during the flight.
- The investigation concluded that the volume of oil leakage required to reach toxic thresholds of ToCP would be so high that it would have caused visible engine failure.