Wake Turbulence?

[sdfcvoh]

This was a landing at Tucson about a week ago.

Can anyone tell if it is the result of wake turbulence (big bump about 1/2way in.) I don't recall a "caution, wake turbulence call." It was an awkward feeling landing, like I've never really experienced before.

[mikecweb]

Were you following another airplane?

[sdfcvoh]

I don't recall that any other planes were around. (I understand WT's causes, effects, and how long it hangs around.)

The way I was effected from the "bump" on all the way to touchdown was just extremely strange. It makes me wonder if another plane took off a couple of minutes ahead that I was not aware of. Anyway - it was strange. Watch how the plane porpoises uncontrollably right before touchdown. Again - it was strange.

[fish314]

At first I thought that perhaps it was a windshear, because it appeared as though you had a lot of left crab in and right when the bump happened the nose moved violently to the right. Also after the bump, the nose seemed to be pretty lined up with the runway. So it seemed like maybe that left quartering headwind died off all at once.

The second time I watched it though, I noticed that the crab began to decrease just before the nose jerked to the right. So that made me think of two possibilities:

1. It could be that the crosswind component was decreasing (and hence the nose was crabbing less and less all by itself) and you were just hit by a stray gust of wind from the left that happened to be pretty strong. The gust hit, shook you a little, and then subsided...

OR

2. It could have been a low level shear that happened. Basically in this scenario, you had some left crab in to get over to the runway, but you had just started to put in your cross wind controls (wing low method). That's why the crab became less just before the bump. But right after you put in the cross wind controls you descended out of the left quartering headwind into an altitude that had less severe of a cross wind component. So the combination of less cross-wind all at once, (and potentially too much right rudder to compensate for a wind that's now no longer there) cause the nose to yaw to the right.

If there wasn't really any other traffic to speak of, that's where I would start guessing. If the winds were reported as either strong or gusty (or both) I would bet on option one. If you happened to notice a sudden change in groundspeed on the GPS (if you have one) right when the bump happened I would bet on option 2.

Every time I've been in wake turbulence (which has been A LOT), it's sometimes felt like a shudder, but usually I notice a definite rolling tendency, not a yawing or sideways push. I also don't normally notice pitch oscillations in wake turbulence, as much as I notice ROLL.

Anyways, that's my guesses. But really it's just a guess.

[sdfcvoh]

Great response. Thanks. I've not knowingly experienced real wake turbulence yet, other than my own propwash during steep turns. I don't think that really counts!

[fish314]

Watching it the 3rd and 4th times, I'm thinking it's a strong gust. I can tell you're compensating for a left crosswind, because I can see you've got left aileron in on the yoke, but your altitude looks to be way too low for it to be "normal" windshear (in other words, it's hard to imagine that a "steady" shear could occur less than 100 feet off the ground).

One last possibility is mechanical turbulence. If there were a building or mountain or something off to the left of the runway that was blocking a wind you might go from no left crosswind where the building creates a "blank spot" to a lot of crosswind in a short period of time. That's the kind of thing that you'd probably notice frequently flying into that airfield.

[sdfcvoh]

Originally Posted by fish314

Watching it the 3rd and 4th times...

One last possibility is mechanical turbulence.

Its pretty barren to the left. It does look a lot like its just a gust. It was just quite different than any I've noticed before. Thanks for taking the time to review it!

[taseal]

it doesn't look like it to me....

last tiem I hit wake turb was of a guflstream, and we dropped pretty hard.... my door jammed actually

[surreal1221]

Is there an intersecting runway/taxiway right under where the bump was?

[sdfcvoh]

I just looked back at it. The crossing runway is about 1000ft before the bump. There is an intersection right after it. Must've just been a gust. It sure was a fun one!

Originally Posted by surreal1221

Is there an intersecting runway/taxiway right under where the bump was?