Abstract
Helicopters have the ability to make maneuvers or precautionary off-airport landings to avoid flights into instrument meteorological conditions (IMC) such as fog. Flight accidents in which fog was encountered as well as inadvertent and intentional flights into fog were examined to understand their occurrence. A 25-year period in the United States using the National Transportation Safety Board online database was used to collect 109 accident reports of which 73 (67%) were fatal. Pilots flying intentionally into IMC were more likely to be a part of a fatal accident than those who did so inadvertently. Those pilots who were reported as being under pressure when encountering fog conditions were also more likely to be in an accident. The findings confirm a high prevalence and an added danger to intentional flights into IMC. In addition, decision-making under pressure when encountering IMC conditions is now linked to a higher proportion of fatalities, emphasizing that helicopter pilots should be made aware of these specific decision-making circumstances in their operations.
Highlights
Helicopters, similar to other small aircraft in U.S general aviation, mostly operate in ClassG airspace, which defines the weather minimums for an aviation operation
Helicopters may operate in Class G airspace under visual flight rules (VFR) when the weather is clear of clouds with only a half-mile visibility during the day time and with one mile visibility clear of clouds during the night
The Federal Aviation Administration only added this visibility requirement in 2014. They increased weather minimums for general aviation, commercial and air ambulance helicopter operations to mitigate, among others, fatal accidents occurring when flying into instrument meteorological conditions (IMC) [1]
Summary
Helicopters, similar to other small aircraft in U.S general aviation, mostly operate in ClassG airspace, which defines the weather minimums for an aviation operation. Helicopters may operate in Class G airspace under visual flight rules (VFR) when the weather is clear of clouds with only a half-mile visibility during the day time and with one mile visibility clear of clouds during the night. The Federal Aviation Administration only added this visibility requirement in 2014 They increased weather minimums for general aviation, commercial and air ambulance helicopter operations to mitigate, among others, fatal accidents occurring when flying into IMC [1]. These rules already existed as advisories prior to this time. Fog is an instrument meteorological condition (IMC) that requires IFR, and helicopters flying under visual flight rules (VFR) are expected to avoid or leave such conditions immediately
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