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FLY SAFE By Ned Parks


Caution: Helicopter Wake Turbulence


It’s past time to educate the entire aviation community about this dangerous phenomenon.


WATCH


an Investigator from France’s BEA on Managing Wake


Turbulence


S


OMETHING SURPRISING ABOUT FLIGHT instruction is just how little is taught about heli- copter downwash—and virtually nothing about


helicopter wake turbulence. There isn’t a mock checkride, or a real checkride, cov-


I can’t tell you the number of times I’ve been told to


“taxi to the pumps and we’ll get you topped off” with a light fixed-wing sitting right there and a trash can with a lid on it 20 ft. away.


ering private, commercial, instrument, or CFI instruction that doesn’t include some conversation about wake tur- bulence from fixed-wing air- craft. Land beyond, take off before, wait 3 minutes. The reminder we’re given goes something like this: “Cleared to land, caution: wake turbu- lence departing 737.” But how often have you heard, “Caution: helicopter wake turbulence,” or, “Caution: wake turbulence


departing/landing helicopter”? The occasion is rare or even nonexistent.


66 ROTOR SEPTEMBER 2022


Notice I’ve used the term “wake turbulence,” not


“rotor downwash.” That’s because the two events are distinctly different and, other than the fact they’re both produced by the rotor blade, have little in common. Downwash is produced while at a hover or during a


very slow hover taxi, whereas wake turbulence is pro- duced with the helicopter in forward flight starting at approximately 20 kt. Downwash in ground effect hits the ground and moves out 360 degrees from the helicopter, with hazardous winds up to 3 diameters the size of the rotor disc. Wake turbulence from a helicopter is more like that of an airplane and moves behind the aircraft while the latter is in forward flight.


They Don’t Know What They Don’t Know Helicopter pilots teach ad nauseam, for good reason, the damage we can do with our rotor downwash. I always teach that being mindful of our downwash is part of fly- ing neighborly. Fixed-wing pilots, however, aren’t taught about rotor downwash or wake turbulence produced by a helicopter.


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