scsmith
Well Known Member
I was cruising north along the Sierra foothills, close to Auburn, when ATC alerted me to a DC-10 Heavy descending across my path 15 miles ahead of me.
The controller initially recommended a heading change 15 degrees right, which would mean that I would have crossed the flight path of the DC-10 farther behind it, and at a point where it had been higher.
I replied that I had the heavy in sight, and the controller said, "resume own navigation, caution wake turbulence."
It looked to me like I would cross the jet's flight path at a point where it was still a few thousand feet above my alt, and about 25 miles in trail. I know that the wake does descend a lot (wake modeling was a big part of my Thesis research), but I just continued on.
Sure enough, right when I was directly in trail of the DC-10, now about 25 miles away, BOOM! I hit his wake. It was a very sharp up-down-up jolt, of which I predominantly felt the 'down'. As I was getting my eyeballs tucked back in where they belong, I noticed that I had a low fuel pressure alarm. About as quickly as I noticed it, the fuel pressure returned to normal. The engine never hiccuped.
I find this interesting. The tank was within 5 gallons of full. So it is not like a big slosh would have left the fuel pickup dry. Or would it? The heave was so fast, and over with so quickly, it is hard to imagine a large air bubble at the outboard top area of the tank could quickly travel to the bottom inboard area of the tank. In order for that air bubble to move, fuel would have to move to displace it.
I wonder if the fuel pressure loss could be due to something other than the fuel pickup momentarily being in a big air bubble. Could the rapid acceleration interfere with the mechanical pump function? I don't know.
My G-meter showed +4 and -2 g's. Thats a +/- 3 g excursion from level flight.
The controller initially recommended a heading change 15 degrees right, which would mean that I would have crossed the flight path of the DC-10 farther behind it, and at a point where it had been higher.
I replied that I had the heavy in sight, and the controller said, "resume own navigation, caution wake turbulence."
It looked to me like I would cross the jet's flight path at a point where it was still a few thousand feet above my alt, and about 25 miles in trail. I know that the wake does descend a lot (wake modeling was a big part of my Thesis research), but I just continued on.
Sure enough, right when I was directly in trail of the DC-10, now about 25 miles away, BOOM! I hit his wake. It was a very sharp up-down-up jolt, of which I predominantly felt the 'down'. As I was getting my eyeballs tucked back in where they belong, I noticed that I had a low fuel pressure alarm. About as quickly as I noticed it, the fuel pressure returned to normal. The engine never hiccuped.
I find this interesting. The tank was within 5 gallons of full. So it is not like a big slosh would have left the fuel pickup dry. Or would it? The heave was so fast, and over with so quickly, it is hard to imagine a large air bubble at the outboard top area of the tank could quickly travel to the bottom inboard area of the tank. In order for that air bubble to move, fuel would have to move to displace it.
I wonder if the fuel pressure loss could be due to something other than the fuel pickup momentarily being in a big air bubble. Could the rapid acceleration interfere with the mechanical pump function? I don't know.
My G-meter showed +4 and -2 g's. Thats a +/- 3 g excursion from level flight.