HaveBlue From United States of America, joined Jan 2004, 2073 posts, RR: 1 Posted (6 years 6 months 6 days 9 hours ago) and read 2112 times:
I've watched this video a few times and was wondering if he hit a wingtip vortice from a preceding aircraft or if it was just a strong crosswind or wind sheer that he corrected for and then was overcorrecting side to side. Thoughts and opinions please.
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 71 Reply 1, posted (6 years 6 months 6 days 9 hours ago) and read 2108 times:
The video would require that I download flash - AGAIN - and I'm not going to do that until they fix flash so it doesn't require downloading every time, when there are already half a dozen instances of it on my hard drive. /rant
I'm assuming that we are talking about SeaTac and the very windy days they had?
If so, there is not much chance of a wake turbulence encounter as the wind will break it up and move any lingering fragments away very quickly.
On the other hand, SeaTac is near the top of a fairly narrow ridge between Puget Sound and the Green River valley. There are steep rises north and west and the Des Moines Creek canyon to the south all of which will cause the wind to spill and roll like a stream over rocks. Arrivals there on a day when the wind is out of the southwest can be downright sporty.
Happiness is not seeing another trite Ste. Maarten photo all week long.
HaveBlue From United States of America, joined Jan 2004, 2073 posts, RR: 1 Reply 4, posted (6 years 6 months 5 days 23 hours ago) and read 1994 times:
Fair enough Slam, I don't blame ya. Thanks for the description of the environment there, I'm not familiar with it.
3D I know how the vortices effect the plane to an extent, I've been in a DC-9 when we hit wake turbulence from a heavy (this confirmed by the pilots of said DC-9). What made me think it wasn't just crosswind was that the approach up til that exact point seemed very stable, didn't look like he was crabbing/slipping or fighting it at all, then all of the sudden the rapid right roll, quickly corrected (or overcorrected) by left roll, and yes the PIO seemed very apparent. I thought maybe he hit the left wing wake turbelence, corrected to the right but too much, then tried to counter with left, etc. You can watch the spoilers quickly go left, right, left, right before he aborts and goes around. If it was a crosswind condition it seems he would have had some correction in there to start, not just a sudden and rapid 90' crosswind affecting the plane.
Speedracer1407 From United States of America, joined Dec 2004, 333 posts, RR: 0 Reply 5, posted (6 years 6 months 5 days 19 hours ago) and read 1963 times:
Quoting 3DPlanes (Reply 2):
I wake vortex event would (normally) be a rapid rolling event, either left or right, followed (hopefully) by a correction back to wings level.
While I'm certainly no expert nor pilot, I did experience a somewhat similar situation aboard a COex ERJ 145 last year on final approach to ORD. We were probably at something like 500 feet or so, and we suddenly rolled left-right-left-right-left-right in rapid succession. It startled everyone on the plane. We didn't go around, but I'd bet money that if the same thing happened at 50 ft AGL, we would have.
Anyway, as we deplaned, nearly EVERYONE asked the pilots what it was all about, and they answered over and over again that it was wake turbulence from a 757 crossing our path at a very small angle.
Dassault Mercure: the plane that has Boeing and Airbus shaking in their boots.
Speedracer1407 From United States of America, joined Dec 2004, 333 posts, RR: 0 Reply 6, posted (6 years 6 months 5 days 18 hours ago) and read 1960 times:
Wait...while my previous post made no specific assumtions about the reason behind the NWA 757's visually dramatic go around, I should probably also point out that the video shows the succcessful landing afterwards, which displayed the same seemingly dramatic left-right roll inputs--right down to the landing in which the left mains touch down DURING a roll moment.
Dassault Mercure: the plane that has Boeing and Airbus shaking in their boots.
Starglider From Netherlands, joined Sep 2006, 644 posts, RR: 44 Reply 7, posted (6 years 6 months 5 days 5 hours ago) and read 1911 times:
Quoting 3DPlanes (Reply 2): Looks like gusting crosswinds, combined with PIO.
Or maybe wake vortex from a nearby building or structure? Here at AMS there was a structure (blast wall of an engine run pad) that created vortices which affected the touchdown area of a runway. They had to lower the wall.
Pilotpip From United States of America, joined Sep 2003, 3084 posts, RR: 12 Reply 8, posted (6 years 6 months 5 days 3 hours ago) and read 1881 times:
SEA has had some rediculous weather the last week or so. Another pilot forum offered this reasoning:
757s are known for getting this roll going in strong crosswinds. It has something to do with the roll spoilers being deployed. Boeing issued an SB for this and has installed vortex generators on the outer leading edge to help with this.
3DPlanes From United States of America, joined Apr 2006, 167 posts, RR: 0 Reply 9, posted (6 years 6 months 4 days 23 hours ago) and read 1856 times:
Quoting Starglider (Reply 7): Or maybe wake vortex from a nearby building or structure?
That occurred to me too, but I'm not familiar with SEA.
I do recall that MSP has issues with the big NW hangar blocking crosswinds and creating low-level turbulence for the two parallels - depending on where the wind is from...
Starglider From Netherlands, joined Sep 2006, 644 posts, RR: 44 Reply 10, posted (6 years 6 months 4 days 15 hours ago) and read 1829 times:
Quoting 3DPlanes (Reply 9): That occurred to me too, but I'm not familiar with SEA.
I do recall that MSP has issues with the big NW hangar blocking crosswinds and creating low-level turbulence for the two parallels - depending on where the wind is from...
A few years ago i arrived and departed SEA regularly. Can't recall anything that stood out to have such an effect on either of the parallel runways. But the only constant is change. So maybe something large enough may have been built there since?
In this case, a 752 approach. I noticed that the upset took place at exactly the same location near touch down. In the video, during both approaches, first the plane passes a double light post in the foreground relatively stable, then hits turbulence near touchdown, in both cases exactly when about to pass the tree branches in the foreground. Second time less severe but still evident.
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