I wrote this up for another forum last year, after I had an encounter with helo turbulence:
So I suppose this is a teensy bit of a cautionary tale, but really more of just an FYI mixed with a bit of confessional. Obviously, I've read plenty about wake turbulence like any certificated pilot, and particularly heard that helicopters can make some strong stuff, but I'd never experienced it until this past Friday.
The scenario was me taking up my club's Arrow just to maintain currency and keep the rust off. Bit of air work off-airport, followed by about half an hour or so of pattern work. It was a Friday afternoon with nice weather, and so the pattern was pretty busy. Mostly just other fixed-wing traffic, but one of the R-22s on the airport was out there as well. In general, they were doing a good job of staying out of our hair; they flew right traffic instead of left, frequently "landed" on taxiways instead of the runway, etc. For almost the entire time out there, I had nothing vaguely resembling a conflict with them.
As dusk approached, the pattern dried up. I thought it was just me up there - I hadn't heard any announcements from the helo in a bit - but as I turned base, I saw a red light about midfield on the runway, and about the time I was figuring out what it was, the helo pilot came up on frequency. "Helicopter 123 on the roll, runway 14." Sure enough, they started moving forward.
I estimated there'd be no conflict, but I squared my base-final turn just for good measure to help keep spacing - but it turned out I'd underestimated the speed differential. As I was on short final, they were just hitting the end of the runway, and they'd already sidestepped to the right, presumably to keep out of my way. I still didn't think there was a conflict, and if there was, going around probably would have made things worse - I just would have closed on him even faster (more on this decision later).
So I continued with my approach, touched down about 500' down the runway, flaps up, power in, let's go. I was maybe 30' above the runway, really just getting established in my climb, when the plane abruptly banked about 30? left. I put in right aileron to correct, but there was no reaction for a moment, and then just as abruptly as before, the plane rolled through wings level and about 20? right. The instinctive thought that went through my head, just based on the airplane doing such drastic uncommanded things, was that something in the control system had broken - like it seemed the ailerons were just doing random stuff instead of what I asked of them.
That thought didn't last long, because the airplane straightened out and resumed obeying my commands. It took about another five seconds for me to put two and two together - it was right at about midfield I'd had the weirdness, about the same spot where the helo had started its takeoff.
All in all, it was a brief moment of weirdness, but not what I'd consider a near miss or anything like that. At the same time, it probably could have been a bigger problem had I hit the turbulence at a lower altitude - say, just as I lifted off again.
In retrospect, there are my thoughts / lessons learned:
- Helo turbulence is no joke. You might be tempted to think a teensy R-22 can't make that much wind, though anyone who's stood near one taking off (and I fall in this category) ought to know better. A larger helo could have put me in for a bad time for sure.
- I didn't do a good job of maintaining spacing with the R-22. I underestimated my closure rate with him taking off and me landing. I also talked myself out of taking any corrective action. As mentioned before, going around probably wouldn't have helped much, unless I'd made a near-immediate left turn at low altitude to clear out. Probably the safest thing to do, in hindsight, would have been to make a full-stop landing; I would have been firmly on the ground, maybe even clear of the runway, before reaching his takeoff point.
- I question whether I was truly listening on the radio or not. I don't recall hearing the helo announce that it was going to be taking the runway; I only heard the "on the roll" transmission. Given how considerate they'd been previously, clearly announcing intentions, it seems unlikely that they did this without announcing, and more likely that I mentally tuned them out, thinking they were no factor. Not a great thing.
Overall, for this flight, I don't think I was on my A-game, which was possibly reflected in some of the stuff above. I felt my airmanship was good - all my landings were on-speed, on centerline, roll-on affairs - but my procedures weren't great. I was sloppy with my GUMPS checks early in the flight, definitely not a good thing in a retract. I chalk some of this up to being a bit worn out after a long day at work, and some of it to being a bit rushed, trying to fit in some flying in the couple hours after work but before sunset. Next time I want to fly on a weekday, I think I'll take a half day so I can have plenty of time and not have to worry about it getting dark. Nothing good ever comes from feeling rushed.
Anyway...confession complete. Fly safe out there.
