Flight lesson: Blown away

Thanks to the radios, we were all staying aware of each other’s position. I was going around the pattern while the R22 was hovering, then making right-hand patterns, and the other helicopter was hovering this way and that, with no apparent purpose.

For one landing I asked the R22 instructor if I could land on the grass. He said, “no problem,” and departed into the pattern. The next time around the larger helicopter was over the grass, so I announced that I’d land on the paved runway.

I had leveled off and was in the perfect landing configuration, just waiting to settle onto the runway, when I passed the larger helicopter hovering about 100 feet off. Suddenly, the wing lifted sharply and the airplane headed for the edge of the runway. The nose was still pointing right down the runway, but we were sliding sideways. I met the ground about three feet off the runway, with one main wheel on the grass and the other on the pavement. I could hear the wheel crunching through the dry grass. A good application of left rudder pedal and I was back on the runway.

Pilots are well trained about avoiding the dangers of wake turbulence behind large airplanes, but little seems to be mentioned about operating near helicopters. Maybe that’s because many pilots train at fields with no helicopters. But think of a helicopter rotor as a 25- to 50-foot-wide propeller, blasting downward with enough force to lift it into the air. Imagine that rotor wash striking the ground and being forced outward, into the path of your light airplane.

Section 7-3-7 of the Aeronautical Information Manual notes that when the rotor downwash of a hovering helicopter hits the surface, “the resulting outwash vortices have behavioral characteristics similar to wingtip vortices produced by fixed-wing aircraft. However, the vortex circulation is outward, upward, around, and away from the main rotor(s) in all directions. Pilots of small aircraft should avoid operating within three rotor diameters of any helicopter in a slow hover taxi or stationary hover.”

There is no safe place to land near a hovering helicopter. Also, like airplane wingtip vortices, these rotor vortices can last more than a minute, so pilots should remain well clear of helicopters—in both distance and time.

Helicopter pilots need to be considerate of their rotor blast, just as airplane pilots need to be considerate of propwash. Don’t perform an engine runup with another airplane behind you, or a bunch of parked aircraft nearby.