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Q: What's the deadliest cat- egory of general aviation accidents? A: Attempted visual flight into Instrument Meteorological Conditions (IMC). According to AOPA’s Air Safety Institute, when a “VFR into IMC” crash occurs, it is almost al- ways fatal. Q: Who's at risk of a Visual Flight Rules (VFR) flight into IMC? A: Experienced, often high- time pilots, in cross-country (not training-type) airplanes are as much at risk as lower-time pilots. AOPA’s Richard McSpadden writes, “a third of these accidents \[VFR into IMC\] happen to experienced, IFR-rated pilots.” Q: When are you most likely to inadvertently enter instrument conditions? A: When beginning or continu- ing a flight into marginal weather conditions. VFR Ceiling great than 3,000 feet and visibility great than five miles MVFR Ceiling 3,000 feet or less, but greater than 1,000 feet and/or visibility five miles or less but great than three miles IFR Ceiling 1,000 feet or less but greater than 500 feet and/or visibility three miles or less but greater than one mile LIFR Ceiling 500 feet or lower and/or visibility one mile or less Barely VMC by Thomas P. Turner There is no official definition of scud running. Yet a picture like- ly pops into your mind. You may envision flight low across the terrain, tendrils of rainy cloud reaching from a low overcast to meet the fog below. You may think of a solid yet rainless overcast, a few hundred to a thousand feet or so above the ground, a bright ribbon of light on the horizon promis- ing clear skies ahead. You might pic- ture a sunny summer day, steamy and hot, so bright with haze that you can't see more than a mile ahead. Or you might consider flight on a dark night, the stars and moon hidden by clouds, 6 • TWIN & TURBINE / April 2020 the lights below you occasionally f lick- ering and disappearing behind wisps of condensation. Visual-rules f light in any of these conditions is sometimes called “scud-running.” Scud running implies an intention- ally hazardous f lirtation with visual flight in near (or actual) IMC. Under some conditions, flight under a fairly low cloud deck or at fairly low vis- ibilities can be done safely. In the context of this discussion, I’ll refer to managing the risks of legal visual- rules f light in marginal VFR (MVFR) conditions. Few pilots routinely fly VFR in this kind of weather, but sometimes it makes sense for short repositioning f lights or oth- er reasons. We need to con- sider technique and go/no-go decision-making when faced with these conditions. When MVFR Turns Worse For the years 2005 to 2014, AOPA’s Air Safety Institute notes 290 NTSB-re- ported accidents involving attempted or continued visual f light into IMC. That's about one every other week, with 85 percent of these accidents fa- tal. Almost two-thirds involve high- performance airplanes, f lown typi- cally by experienced pilots who are often instrument rated but chose for whatever reason to fly VFR in mar- ginal conditions. VFR into IMC acci- dents in high-performance airplanes are over 90 percent fatal. These types of accidents are avoid- able with prudent pilot decision- making. With awareness of the MVFR threat even to experienced pilots, we can derive some recommendations for operation in and around marginal weather conditions and apply knowl- edge of the conditions that lead to MVFR and IMC to manage the risks and remain in command of your f light. Risk Management and Mitigation In an overwhelming number of these accidents, less-than-VFR condi- tions were reported well before the crash. We’re living in an age where weather data is widely available before and even during flight – all we have to do is look. Check at least once an hour on long trips. Jot down notes to see if the weather trend is improving or deteriorating next time you look, and to verify or refute the accuracy of the “SVFR \[Special VFR\] allows for graduated risk in decision making. If CAVU represents the least risk, IFR in VMC is perhaps a little less, IFR in IMC a little more, and SVFR is a little more than that.” – Paul Bertorell