Flying VFR around the Bay Area I’ve had two experiences recently that made me a bit nervous, but I haven’t been able to find recommendations that fit the situation.
The first was flying (C172) north along the east bay hills somewhere between OAK and LVK, around 3500’. We saw a 737 descending towards OAK ahead and above us, crossing right to left. 2 or 3 minutes later, long after I’d forgotten about it, I think we crossed the descending wake: we felt a single very sharp bump, hard enough to feel like we’d hit something.
The second time, I was crossing the bay just east of SQL on a northeast heading. ATC pointed out an A380 on final to SFO ahead of us. They passed in front and above us, and I turned to cross their path at 90 degrees, thinking this would be the right strategy for minimizing the risk of being rolled by the vortices. When I later checked the flightradar data, they were about 1000’ above us where our paths crossed. We never felt a bump, though the controller who watched this asked me how the turbulence was, so he evidently thought we were taking a risk.
Of course I know the mantra about wake turbulence is to just avoid it. But in practice, in a situation like this, I might have to divert for 5 minutes or so to try to fly “around” the wake area (e.g., in this case turn SE paralleling the flight path in reverse before turning back on course) and it seemed to me that crossing a wake at 90 degrees seems like a reasonably safe thing to do, a couple of minutes after the plane had crossed (though I couldn’t really judge the vertical separation).
I can’t find anything in faa docs on this situation. They’re all about takeoff and landing. And the bad stories about planes being damaged/destroyed by wakes seem to always involve a near 0 or 180 relative heading (i.e., flying along the vortex line so the two wings see a large force difference).
I’m curious what others think about this.