Huntsville to ATL: Wake turbulence event

[Huey]

Okay y'all. I experienced a wake turbulence event on my ride to Atlanta yesterday, and I figured I'd tell you about it, since I think I can describe it and ease some fears.

Most of you know that I have experience flying small airplanes and that I have been a frequent traveller for the last 18 months or so. (I'm typing this from the Norfolk Airport Hilton Cyberbar, and this keyboard is iffy, so excuse the typos.)

We took off from HSV on time in a 737-200 into a clear, 50 degree sky. We made our way to 14,000 feet and flew for about 20 minutes before approaching ATL from the northeast, after passing over Rome. I looked out the right window and saw parallel traffic at our altitude, and it looked to be a 737, also on approach. I saw him start down, saw our spoilers (brakes) come out, and then observed him turn about 30 degrees to starboard. About 20 seconds later, we turned about to about the same heading. So now I am aware that we are following this guy in. The flaps dropped to what looked like about 20 degrees. (I'm guessing we were at about 200 kts at that point.) The flight had been almost perfectly smooth to this point.)

I then felt a sudden drop, the nose of the aircraft swung right and the left wing dropped a bit. There was (according to my Mark 1, Mod 0 ass/attitude detector) a good indication that we were uncoordinated for a moment. Engines came up to what I would guess is about 80% power. The nose went left past centerline (and come up a bit) and the right wing came up, and then I saw the aileron deploy upward on the right wing, which lowered that side. The nose centered, and we were through it. Total event time was about 3 seconds.

I turned to the (now wide awake) seat neighbor and as he asked, "What the F&*^, over??" I told him I thought we'd just passed through wake turb from crossing traffic. (As an aside, I've felt knuckles in the air as I complete a 360 degree turn, which indicates arriving right back where you started from. There's a dip when you do that, too, but it's expected, because, hey, I'm a @#%$ hot Cessna pilot.)



Make no mistake, you KNOW you just went through something, but it was over almost as quickly as it began. I lagged back and asked the Captain whether my suspicions were correct, and he replied in the affirmative. It took them by surprise, too. He told me it felt like a 757 had crossed our path on departure.

My thoughts are that the still air had prevented the wake turb from dissipating quickly enough in the otherwise still air. The turb descends at about 900 fpm, and wind will push it as it falls. There were light winds, but the air was so stable that the turb was able to hold its "shape" for a while, and the departing airplane may have crossed us at just the right time to take the turb into our flight path.

I don't post this to scare the living @#%$ out of anybody, and PLEASE don't expect this when you fly. I have around 50 segments in the last 18 months, and this is the first time I've encountered this. The aircraft recovered very quickly, and the rest of the ride, and my next to Norfolk (ORF for you 3 letter snobs out there) was uneventful, too.
In fact, my seat neighbor flies every week, and it was the first he'd encountered, too.

The simple fact of the matter is that these events, though sudden, are flown through quickly and don't alter the flying capabilities of the airplane. One more note, the pilot told me that that was one of the worst wake turb encounters he'd seen. It actually wasn't that bad, once the initial abruptness of it passed.

Anyway, the moral of the story is that wake turb does occasionally happen, and that you'll live through it.

[beaugest]

"Anyway, the moral of the story is that wake turb does occasionally happen, and that you'll live through it."

You are discounting the possible heartattack...:\
Actually, Huey, I found that helpful. I usually don't get bothered by stories of events that happened. The first thing that comes to mind is---the person is around to write about it...
and even though I don't know that I'm grasping the concepts 100 percent your very thorough response reminds that there are people that really, really understand how these things work.

[Passenger Mark]

For us to pretend that this stuff does not happen is heading in the wrong direction.

Accepting that it might happen, but the plane and the passengers are going to be fine is heading in the right direction.

Thanks for the info Huey, it is a first hand report that once again, things may not always be comfortable, but they are safe.

[Huey]

Beaugest:

Okay, what happened was that another aircraft (that the Captain judged to be a 757, but we don't really know) crossed our line of travel at a higher altitude and upwind of where we encountered the wake turb. You might recall that when an aircraft generates lift, it does so by passing air over the curved surface of the wing. The curvature, or "camber" of the upper wing causes the air flowing over that curvature to accelerate to a speed that is faster than the air flowing under the wing. When the air on the upper side of the wing speeds up, its pressure drops.

Since we now have lower pressure over the wing and higher pressure under the wing, we have an unbalanced force, which pushes the wing up. This is the Bernoulli principle.

But at the tips of the wings, we get "spillover" as the higher pressure "lower wing" air tries to get to the area of low pressure on top of the wing. This creates a "wingtip vortex" at the end of each wing. These vortices, combined with the other displaced air coming back from the wings and fuselage of the aircraft, creates a wake of air. This wake turbulence is more pronounced when an aircraft is heavy, slow, but producing a high level of thrust. This is the scenario at takeoff, but wakes are being generated right until touchdown.

So an aircraft was likely climbing, was big (a 757) and generating climb-out power. The wake it generated descended (at around 900 fpm) and travelled downwind in the light breeze without dissipating. It just happened to be at the same altitude we were at, and we flew across the wake, with its spiraling winds and general air mass disruption. These winds obviously acted on our airplane, and either the autopilot or flight crew had to react to them, which they did with great speed.

While this is not terribly common, it does happen once in a while, although it tends to happen when the aircraft isn't vulnerable to problems. This is because the flow of air traffic at lower altitudes is such that departing traffic and arriving traffic are separated, and warnings are issued when a wake may be encountered. When an airplane departs, enough time lapses that the wake descends out of the way of the next guy in line to depart, and arriving traffic is kept above the wake as it descends. Were were at about 8,000 feet, I'm guessing, when it occurred, and it was a momentary blip for us.


Now, I gotta sign off and go. I gotta ticket for an aeroplane, ain't got time to take a fast train. Lonely days are gone, I'm ah goin' home, my baby wrote me a letter.

[canoga]

" I lagged back and asked the four striper whether my suspicions were correct, ........."

I swear to gawd I read this three times and thought it said, "I lagged back and asked the four strippers...."

I was wondering what Huey was doing on a plane with 4 strippers then I realized I didn't want to know.

Beth
:banana

[noflyingfan]

:hamster :hamster :hamster :hamster

[WillFlyToDisney2]

No, the person on this board most likely to be on a plane with four strippers would be KEN! LOL

Four STRIPERS are Captains. Three STRIPERS are First Officers. :) And then there are Candy Stripers...

Kelley

[spiffyone]

Dude, I used to be a candy striper.

Now I look like this >>>:hamster

Huey, since you fly a lot and understand what can and can't happen on planes, tell me this : Why do you think the wake turb event was initially scary for you? I mean, you knew the plane wasn't going to fall out of the sky. Do you think it was the disconcerting feeling of sudden movement when you weren't ready for it? Do you think we have, like, a fight-or-flight type mechanism that "alerts" when there is a sudden movement or a feeling that "shouldn't" be?

I am trying to figure out why those little movements are scary even though I know logically that things will be OK. Humor me. What do you think it is?

:hamster :hamster :hamster :hamster << 4 strippers?

:dancers << or would you rather have these ladies?

:peace :peace :peace :peace << or maybe her

:troll :troll :troll :troll << but probably not him.

spiff

[beaugest]

Spiff, good question. However, since I'm authorized to diagnose from afar(being all knowing,etc). I would say that Huey was experiencing the realization that the 4 strippers were not on board...which if they looked like this:troll :troll :troll :troll
or :hyped :hyped :hyped :hyped would really be a good thing...

[YankssRule]

This lil added ditty..made me laugh the hardest:

quote: "my own pucker factor was high enough to suction cup me to my seat" :rotflmao

:hamster :hamster :hamster :hamster :hamster (Since we have no "pucker factor" emoticon..this will have to do)

Janet
:dancers

[spiffyone]

BTW, we're still on for early lunch next Friday right?

Sheraton Braintree, 11:30?

:coffee :coffee :coffee :coffee

[Huey]

"Why do you think the wake turb event was initially scary for you? "


I never used the word "scary".


I was alarmed for a second or two because this was a totally abrupt upset of the stable flight, and because the aircraft went into "uncoordinated" flight for a couple of seconds. ("Uncoordinated" means that the yaw and roll of the airplane weren't "in synch".) There was even a dead heading crew about 3 rows in front of me and their heads popped up and looked around until we settled back down.


When you walk around a corner in your home and Duncan is there and you didn't expect Duncan to BE there, are you startled? Why? Don't you feel safe in your home? I mean, sheeeeeit.


Added by edit: I guess the difference is that some people's dial is set higher. This was not light or moderate chop, or something to that effect. I knew where we were in the pattern, knew that we had one or two more turns to make, and had a good idea of what was to take place and when. Turbulence is ordinary and normal. WAKE turbulence is rare and unexpected, since if you expected it, you could have avoided it. I knew immediately that something was wrong. I guess (without sounding like a smartass) the difference is that I can tell the difference between what is normal and what isn't. I don't mean that to come off sounding smug, but it's true. I don't sweat a bumpy ride and the dips that come with it. Like I said, I saw the airplane was under control and returning to "normal" flight and I relaxed.

[spiffyone]

That's what I was getting at, though - that a lot of the sensations that are familiar to you are not familiar to us, so they feel as "startling" to us as the wake turbulence felt to you.

I guess I was just trying to figure out whether it was the motion itself, the unexpected motion, that was startling, or whether there was something inherently worrisome about wake turbulence that was startling instead.

P.S. I never use the term "pucker factor," so we're even.

:pokefun

[Huey]

I see your point. I don't know that I can explain it any better than you did, then. Most of the sensations of flying are already familiar to you, as familiar to you as they are to me. I just don't associate any of them with danger. Any of us can get caught off guard by a sudden dip, and being surprised is no big deal.

[spiffyone]

Huey, thanks for your discussion of "uncoordinated" flight. I can testify to how disconcerting this sensation can be. I once flew from Raleigh to Columbia, SC on now-defunct Midway Airlines. (I'm a three-letter snob, too: this is RDU to CAE. I actually am glad I knew these codes because the hapless Midway clerk in Boston initially tried to check my baggage to Columbus, Georgia.)

This was in a 15-seater with no bathroom and no barrier between the passengers and pilots. I think they did provide barf bags. It was about 100 degrees that day. The pilot turned around and warned us that it was rough flying that day, because there were lots of updrafts.

I am usually a good flyer, but this trip really taxed me. Your description of "uncoordinated" flight describes what we encountered. We would be going along and then it would feel like you drove your car into a ditch at 30 mph. And then the plane would rotate in all three dimensions at once for a few seconds. :nono

It was uncomfortable, but I made it to the other end in one piece. Actually, the worst part of the trip was the return, when I got stuck in the Raleigh airport for about 5 hours while thunderstorms tied up the entire northeast. The Midway clerk made wonderfully helpful announcements like, "We don't have an update for you, but we'll update you again in 15 minutes when we know when the update is." :thumbsup Boy I miss them.

[spiffyone]

P.S. That was a trip to visit his girlfriend from BEFORE.

Her >>>>:anon

Me >>> :hamster

I am cooler.

[Debbielevis2]

Huey/spiff

I have also experienced wake turb. I know this, because I was told by the stripper - er, striper - um, Captain (yeah, that's it!)

Anyway, it was mid-October, landing at Sky Harbor (PHX). My daughter-in-law was with me, and we were just gliding along, coming in for a landing, happy as can be, when suddenly - SLAM!!! Swoop - dip - swerve, Kim grabbed my arm and bellowed, "What the @#%$ was that?!" She said, "what was" rather than "what is", because it was over that quickly. The Captain actually came on and said, "That was so our Fearful Flyers in the cabin can report back that they've experienced wake turbulence!"

I was not scared by it, because by the time it registered, it was over. Also, the Captain's alerting us to what it was took the "pucker factor" away.

And, spiff - yep - 11:30 a.m. brunch! Yummy!

Deb

[JamieAllison]

I appreciate hearing stories like all of these. They help me remember that scary things can happen on a plane, but they don't always (or even usually) mean disaster.

I wish all pilots would make announcements like the one on Deb's plane. It's so awful when something happens and you have no idea what it is or what it means. They probably don't announce anything because it's no big deal to them, but it's always hard for me not to think the worst (big surprise!).

Jamie

[canoga]

Okay guys. After these descriptions, I think I have experienced wake turb. I can't remember which flight it was but we were landing back in Cleveland when all of the sudden the plane went dip, swoop, plunge, wobble and then immediately righted itself. It was over in an instant.

Of course the Continental pilots never said anything to us. I believe a requirement for the job is that they have their voice boxes surgically removed.

Anyway, I'm never scared on approach so it really didn't phase me. I'm usually so ****ed excited to be getting back on solid ground that I need a cigarette before I roll over and go to sleep.:smokin

Beth

[beaugest]

Beth, I know exactly what you mean about the Continental pilots. Newark is their hub so that's turned into my comfort "airline." But sometimes, I wonder if the pilots are docked if they use up a certain amount of words.
I do think hearing about events like this are important. If something like this should happen, we will know it happened before and the person was alive and well or he wouldn't have been typing the post...
Spiff. Yes. to Fri. Looking forward to it. Just look for the person who looks like this...:hyped (Pillsbury Dough Girl's twin sister...).

[canoga]

I fly almost exclusively with Continental. Cleveland is a hub too. I can not remember one single time a pilot has come on to explain anything.

On the 1 AW flight and the 1 SW flight I have taken, both pilots came on to say everything was going fine and if you look out the window you can see the Grand Canyon and.... It was fabulous. In fact, the SW capt was cracking jokes that were truly funny. I lurve me some SW but the flights never work out well.

[ChrisLynch]

"I lagged back and asked the four strippers...."

I saw that too it must just be my mind:angel

Your description sound just like what I encountered on a MyTravel lite Airbus A320 on the way into Malaga, it did not really bother my as it was about 3 seconds and we were circling on the way in to land (my favourite part of the flight) so I did not really think about it, just had my heart jump into my mouth, but was glad it was over. The turb I don't like is constant bumping around all over the place.

Chris

[Disney fan]

Chris,

I agree, I can cope with a few seconds of anything! What I don't like is the constant bumping around for ages.

Lynda