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High Altitude Flying 101

J

jtppalmer050390

Member
So my wife and I flew to middle GA this weekend. I always fly around ATL class B. However, this time we were flying much higher than I usually fly. We were at 9,500 ft and saw a plane on my ADS-B. Looked to our left and it was a Southwest jet. It crossed two miles in front of us and we saw it clear as day. Really cool to see and then I started thinking about wake turbulence. I immediately started to climb and by the time I got to were the jet had passed in front of us, I was 500 ft above its path. We didn't feel any turbulence at all. I was just wanting to ask everyone if this is what they would have done? Also, if we had gone directly under its path, would we have gotten a lot of turbulence? What is a safe distance to avoid serious wake complications?
 
Wake turbulence is at it's worst when the airplane producing it is slow and dirty with high AOA - which is takeoff and landing. When they are cleaned up and at cruise speed the wake is quite a bit less. Not to say it's so small that you don't need to be concerned about it, but it's quite a bit less.
 
airguy said:
Wake turbulence is at it's worst when the airplane producing it is slow and dirty with high AOA - which is takeoff and landing. When they are cleaned up and at cruise speed the wake is quite a bit less. Not to say it's so small that you don't need to be concerned about it, but it's quite a bit less.
Click to expand...


Actually, wake turbulence is worst when the aircraft is heavy, slow, and clean. Reference AC90-23G for more specifics. A jet below 10,000 isn't going to be traveling at it's optimum speed since it's restricted to 250KIAS so it's def going to cause more turbulence than were it at cruise.

With respect to the original post, wake turbulence tends to descend on it's own so you likely had ample altitude separation but absolutely nothing wrong with your actions and you're ahead of most by even considering wake turbulence. Good call!
 
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+1 to what was said.

Adding only that while the vortices will typically drift down and out from the aircraft winds, the local wind will affect the path. So crosswind, lifting or descending air will affect the path/location of the turbulence.

I think climbing for a little more margin was a good choice.
And after all, +500 feet is a simple tug and push of the control ... easy peasy.
 
Flight of 3 Once

I had the same issue one day with a flight of 3 C-17s. The controller actually told me caution wake turbulence when he pointed out the traffic.

Climbing was a good choice and avoiding it is the best plan.

When we cruise across the oceans in airliner business we are all on the same routes, if a jet is above us by 1000' we expect to hit the wake once they are 10 miles ahead of us. So we would offset 1-2 miles right, unless the wind is pushing the wake to the right, then I would just stay on course.

The point being is that the wake will slowly descend and it would fall 1000' over 10miles. I have been up with big planes a few times but only with the C-17s did I hit any wake and it was not much but I passed 5 miles behind them and was 1000' lower, it was just a little bump.

Try to stay above and up wind when passing.

Cheers
 
This sounds likes a very good thread for the Safety section. There, it would reach a much wider audience.;)
 
I assume you were on a VFR flight and not utilizing Flight Following. If you had been on FF, ATC would have/should have warned you and you could have advised them of your decision to climb for wake turbulence avoidance for additional situational awareness/separation of additional flights. ATC was probably advising the big guy about you. The ADSB is nice though!

Bevan
 
When Im not at home enjoying fun airplanes,I have to go to work and fly bigger airplanes. We routinely ask for left / right offset to avoid wake. This is very common on busy airways, arrivals, and approaches. I have no doubt the fun airplanes we enjoy can get dangerously tossed around if one gets too close.

If using ATC, remember they are there to help and understand a wake avoidance request via up, down, or sideways is free and a good idea. When following behind other turbine traffic we are always ready to ask for something as soon as we feel a ripple.


An encounter might not make you crash, but can certainly give any one of us a good scare.
 
i'd probably have stayed at my altitude but deviated behind him until he was abeam.

Same concept - let the wake playout - but deviating behind is less control changes and looks better on the radar track.
 
Big Sky, Little Airplane...

jtppalmer050390 said:
So my wife and I flew to middle GA this weekend. I always fly around ATL class B. However, this time we were flying much higher than I usually fly. We were at 9,500 ft and saw a plane on my ADS-B. Looked to our left and it was a Southwest jet. It crossed two miles in front of us and we saw it clear as day. Really cool to see and then I started thinking about wake turbulence. I immediately started to climb and by the time I got to were the jet had passed in front of us, I was 500 ft above its path. We didn't feel any turbulence at all. I was just wanting to ask everyone if this is what they would have done? Also, if we had gone directly under its path, would we have gotten a lot of turbulence? What is a safe distance to avoid serious wake complications?
Click to expand...

Hi Tommy,
First, as a 737 Pilot for the Company who's wake you avoided, glad you saw us!
Secondly, as mentioned above, 9,500' in an RV isn't really high altitude operations, a better descriptive title for this episode notwithstanding...
There are lots of great videos on wake turbulence and the avoidance thereof, searching the web will keep you entertained for quite awhile.

Good job avoiding the wake, even in large jets it can get your attention when you enter it, especially when slow, configured for landing and behind a Jet with "Heavy" attached to their call-sign.
ATC does that for several reasons, not the least of which is to identify them as a wake turbulence hazard.

V/R
Smokey

PS: Flight following when over or around class B airspace is not only a good idea, but de-conflicts YOU (little guy) with US (bigger guy) and helps your SA immeasurably :)
 
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Think about the question in a different way

Two miles at 180 MPH it takes 40 seconds to be where the other aircraft is now. Would you want to fly through the wake 40 seconds behind a jet? Now think about the jet weighing 200,000+ pounds and flying through the wake in plane with a gross weight of 1800 pounds. :eek:
I would say good call to move up.
 
I'm a retired controller (center controller), the only time we are required to issue a wake turbulence warning is dealing with jets that are capable of taking off weighing more than 300k pounds. I have had JetBlue pass right over top of me (I was at 10.5, he was about 1k above me) on the same course. Not even a ripple.
 
Since I am building a fast RV 9A, I would have just passed him and let him feel my wake!

I had to deal with rotor wash today - and everyday at my hangar. KEUL has a very active helicopter school and they blow things around quite a bit. They played heck with some painted parts today. I imagine landing behind one of them would be interesting. They land on the taxi way here but it is pretty close to the runway.
 
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