A380 wake turbulence - it's wider also

[Ivasrus]

Airservices Australia has re-written A380 wake turbulence standards in the application of parallel approaches to offset threshold medium-spaced parallel runways as applies to Sydney. See map

Previous situation: 34L and 34R approaches were treated independently for application of wake turbulence (lateral separation > 0.5 NM).

New temporary instruction (precis): When A380 on final 34L, wake turbulence spacing is applied to aircraft on 34R final when there is sufficient crosswind from the left at 2000 FT.

This is the result of a single encounter where a SF34 had a "severe" wake turbulence encounter behind an A388 on the parallel approach. There was approximately 20kts crosswind at 2000 FT. It will be interesting to see the outcome of further investigations and whether or not ICAO will review the standard. There is a giant can of worms being opened here.

[HeathrowAirport]

direct.no.speed

Sufficient Crosswinds are the were the cross wind gets to a point that rudder control to counter the yawing moment due to the crosswind is needed.

Regards,

HeathrowAirport

[Roffa]

Err, I would think sufficient crosswind means sufficient to blow the vortex wake over to the final approach of the parallel runway.

No doubt what that crosswind strength is will be published in local procedures.

[HeathrowAirport]

I would have thought in the law of physics a wind sufficient (strong) enougth to blow a wake vortex over a few 1000ft must be sufficient enougth to a point that rudder control to counter the yawing moment due to the crosswind is needed.

Im not a pilot but im just considering what i was taught.

Robbie

[splitduty]

Robbie,
be a good lad now---run off and play with the toys Santa just brought you.

[Spitoon]

Ahh, splitduty, I think you're being a little unfair.

Robbie clearly has an enthusiasm for the topic and, despite probably having no relevant knowledge whatsoever, is keen to make pronouncements which are either completely wrong or of no assistance at all. With characteristics like those he's surely got a great future in ATC management.

[HeathrowAirport]

I used google just now and found a few articles on Sufficient Crosswinds and they all say the same, I am just using what my science teacher taught in physics and this to back it up.

The plane should be aligned with the runway centerline upon landing and the pilot will use whatever rudder pressure is necessary to keep the aircraft aligned with the centerline. The pilot also will correct for any crosswind by banking the upwind wing into the prevailing wind enough to keep the aircraft from drifting off the centerline. Sometimes, if there is sufficient crosswind, the amount of cross-controlling is substantial and noticeable. In the case of a gusty crosswind the pilot almost must wrestle with the aircraft controls to keep the aircraft tracking the centerline of the runway without drifting off downwind.

Santa Ynez Valley Journal | PLANE TALK

Regards,

Robbie

[Roffa]

Robbie,

Your quote above is about a crosswind that is sufficient to require a certain control technique when in the final few feet of landing an aircraft such that there is no drift as the wheels touch the ground.

That's not really the same as a crosswind that is sufficient to move wake vortex at a few thousand feet up. Your crosswind landing technique isn't really relevant if you're upset by the wake of an A380 at a few thousand feet up!

[PPRuNe Radar]

Lucky this isn't on the GA Forum, or we could have a very long debate about wing down vs crabbing techniques

[Roffa]

Robbie, to save you the trouble, click here

[Ivasrus]

Originally Posted by direct.no.speed

What is sufficient crosswind?

For the purposes of the TLI, > 15K.

And for the pedants, this context of sufficient crosswind is that between 2000 and 3000 which moves the wake horizontally towards the other final.

[055166k]

Robbie

Keep the dream alive, you might make it. Unfortunately we in ATC are used to being thought of as very much second-class to the pilot fraternity.....and your earlier posts do you no favours in this regard.
Much as I respect the "Santa Ynez Valley Journal" it may not be the foremost authority on A380 wake turbulence. By the way, the UK has a range of differences to ICAO wake turbulence separation criteria; for example the UK has more weight categories. If you wish to know more about the UK seps for A380...look up ATSIN 137 published by the CAA [21st August 2008].
It would be good advice to think before posting on here......I would expect you to be asking questions rather than answering them if your age is accurately portrayed.
Good Luck

[bekolblockage]

What is sufficient crosswind?

At the risk of giving a serious response to your question, I would guess that "sufficient" crosswind would be such that the wake would drift onto the adjacent final path within the required dispersion period for same runway arrivals. e.g. If 6NM spacing is required this equates to about 2.5 minutes.
If , for example, the runways are separated by .75NM then a 20kt crosswind would encroach on the adjacent path in about 2.25 minutes, thus being a factor.

(Feel free to challenge the maths, I'm getting an early start for NYE )

[055166k]

Ivasrus

Serious comment for you.
I did a couple of years in our HQ office that dealt with Wake Vortex, and your thoughtful inclusion of the respective runway layout has all the clues.
The vortex as we know is a rotating cone from the wingtip .....it also descends.
The clues in your case are the sidewind, the descending vortex, no ground features such as buildings or topography to break up the cone [overwater with possible energy uplift], and the degree of offset between the respective runway thresholds meaning that the SF34 would always be below the equivalent glidepath of the upwind parallel approach.......i.e. begging for it!
Your guys have probably figured this already.....just avoid the situation.

[Ivasrus]

Now a thread in R&N raises the possibility that, shock horror, 1000 FT doesn't quite cut it for A380 wake ...

Armavia A320 turbulence at cruise, A380 wake