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Wake enroute

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Wake enroute

Old 12th Nov 2018, 07:26
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Wake enroute

Hi all,

Iíve been flying for close to 20 years now. The risks of wake turbulence has always been on my mind but more so over the last few years as I went from a medium jet to a light one.

After scouring the interwebs for numbers and information I canít really find any specifics. My main concern is with the A380 but obviously also other heavy aircraft.

As far as descend rates of a vortex, Iíve seen anything from 300-700 fpm.
There are statements that a vortex wonít descend more than 1000 feet in total.
That they donít last longer than 3 minutes. I feel this might not be conservative enough.

The questions I have are if anyone has any solid info on (relating to A380):

A. Lifespan of a vortex.
B. Max vertical movement.


Obviously things like atmospheric conditions and weight of the traffic will effect but assuming worst case is what Iím looking for here.
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Old 12th Nov 2018, 17:08
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There are many, many factors. Atmospheric conditions being significant. Are you looking for details on final approach or enroute?
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Old 12th Nov 2018, 17:54
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German Challenger Totaled After A380 Wake Turbulence
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Old 12th Nov 2018, 18:00
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All I know is that I stay well clear of the recent track of an A380. I just missed one a few months back and it caught the wingtip of our 737 and gave the whole plane a shake. Crossing 1000ft under him, we almost passed through his visible wake, but I turned to avoid and just caught it, maybe 10nm behind him...
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Old 13th Nov 2018, 01:43
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I fly a heavy but have still experienced nasty jolts passing through 380 wake.

To be safe I would be conscious of wake even up to 40 NM away. That would equate to around 5 minutes. Sure that's probably a bit too far to really effect you but I wouldn't play around. Inside of 20NM I would consider wake turbulence critical.

If you are visual with the aircrafts contrail then expect the wake to start with the contrail and then descend below it. So if the aircraft is we'll passed you don't worry about flying through it's contrail if it's near then don't

Yes it's totally dependent on atmospheric conditions but as a rule of thumb if passing behind, take the wake aircrafts distance away from you when you expect to cross it's wake trail and multiply by 50 to get a reference altitude then take a window of plus/minus 500 feet. I.e. if aircraft is 10NM then x 50 = 500ft. So take a window of 0-1000ft. At 20NM x 50 = 1000ft so window is 500-1500ft. If you're passing behind at these altitudes then take wake seriously. (Past 10NM I would even suggest adding plus 1000ft to the reference altitude)

It's not an exact science but I hope it keeps you safe.
​​​​​​

Last edited by Airmann; 13th Nov 2018 at 02:30.
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Old 13th Nov 2018, 14:18
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Thanks Airmann.

My thinking are along the same lines and I exercise extreme caution. 2000 below I still consider it a risk and up to 5 minutes after.

But this is mainly based on feelings and guesses rather than anything solid.

I really wished there was some study to say "a vortex can/cannot descend more than 2000 feet" or "The vortex of a A380 in cruise holds energy for up to 5 minutes".

I find it utterly bizarre that this is not part of a certification process for a new aircraft. It should be up to Airbus when designing the monstrosity to study how badly it will effect other traffic.
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Old 13th Nov 2018, 17:34
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There was a wake encounter at DBX, A320 on final to 30L, hit a A380 wake from 30R at about 500 feet, rolled 40 degrees left, then 40 degrees right, ended up landing on 30R.

There are some studies now of the FDR data, using an equation equating to the sudden change in G force (how ever small). There are far more wake encounters that previously known. Also, most drivers dont take the time to report an encounter.
Using this data, there is are studies to determine acceptable levels of wake encounter.

It is not only the A380 to worry about. One of the deadliest ones I have measured was from a B787. The same high velocity, but a larger core, and long lasting. Many measurements of this ac in many conditions. Heaven help a 320/737 variant in trail to one of those.
Similar wings, although not as upswept, the A350, but only measured that ac once.

On the trail. The conditions that cause a trail do have significant effect on the wake. You will notice on many of the videos, the rollup does not occur very much below the ac, and does not appear to drop very much relative to the ac position. You can actually watch the wake slow to a stop not too far behind the ac.One has to believe that the conditions have to slow the wake down quite a bit.

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Old 13th Nov 2018, 17:42
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Thanks Underfire, nice post.

I always assumed that the A380 had extra nasty wake because the wings are too short and therefore giving a high wingload. I wouldnít have thought a 787 would give very bad ones though.
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Old 13th Nov 2018, 19:58
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Knold,

The size of the vortex is directly related to wingspan. Terminal velocity, which is the highest velocity the air can achieve, is constant through all aircraft types. The size of this core is not. Looking at the A380 in the video, you get an idea of the size of the vortex on rollup, note that it is about exactly the length of the individual wing.
What you do see remaining is the high velocity core of the vortex.
Note that the wake core is not really descending in this video. (nor drifting sideways)

look at this beast of a wake...

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Old 13th Nov 2018, 20:30
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Two questions:

1. What do you consider a light jet?
2. A380 is used for long range/ultra long range so what makes you think youíll be encountering it?
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Old 14th Nov 2018, 03:11
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Originally Posted by B2N2 View Post
Two questions:

1. What do you consider a light jet?
2. A380 is used for long range/ultra long range so what makes you think youíll be encountering it?
1. In my case I fly a Challenger 604. I would consider any BizJet a light one.
2. What do you mean? Because they can fly for 15 hours they are somehow on different airways? I don't think, I know. I encounter well over 20 every time we go flying. Try flying from the ME up to Europe without using the A380 expressway through Iraq and Turkey. Go back to sleep buddy.
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Old 14th Nov 2018, 08:59
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Originally Posted by B2N2 View Post
2. A380 is used for long range/ultra long range so what makes you think youíll be encountering it?
This is way off the mark and completely irrelevant, if it's in the air for 5 minutes there's always the possibility of encountering it

Plus the A380 is used for short/medium-haul the world over. Didn't EK announce DXB-DOH @ 55 mins...... CZ use it on sub 4 hour sectors then there's Europe to the Middle East @ around 5 hours
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Old 14th Nov 2018, 11:00
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The corridors for flights out of the Gulf through Iraq/Iran to the North West basically consist of only around 2 or 3 airways. And are used by the airline with the largest number of 380s in the world.

For this reason pilots out of Gulf are now hyper consious of 380 wake. I have myself hit 380 wake twice in the last three years in a heavy. And it was the same as hitting the wake of a heavy in a medium Jet. We all know what happened to the German business jet that flew through the wake of a 380 over the Arabian Sea.

Unfortunately, or fortunately it was not until that event that the 380 wake problem became well known enough to wake up the authorities. However, the issue is still not officially dealt with. ATC need to be more aware when a 380 is around and be especially careful when a light or medium jet may be pottentially crossing it's path. That could mean a call to the pilots of the light jet of the precense of a 380 or to enforce stricter seperation minimum.
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Old 14th Nov 2018, 11:34
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That could mean a call to the pilots of the light jet of the precense of a 380
i hear that call quite frequently in europe. e.g. "you are crossing x miles behind an a380, can you accept that?"
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Old 14th Nov 2018, 15:38
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and the 747 series doesnt make a wake...
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Old 14th Nov 2018, 15:45
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Originally Posted by Knold View Post
1. In my case I fly a Challenger 604. I would consider any BizJet a light one.
2. What do you mean? Because they can fly for 15 hours they are somehow on different airways? I don't think, I know. I encounter well over 20 every time we go flying. Try flying from the ME up to Europe without using the A380 expressway through Iraq and Turkey. Go back to sleep buddy.
Legitimate question ace.
I consider a Ďlightí jet like a CJ2 or Phenom.
If you fly exclusively domestic USA on demand charters you will not encounter a lot of A380ís

You could have put your area of operations in your original post. Would have helped.
How about paying attention any time you hear Ďsuperí on your frequency.

Last edited by B2N2; 14th Nov 2018 at 17:32.
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Old 14th Nov 2018, 17:42
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Originally Posted by B2N2 View Post


Legitimate question ace.
I consider a Ďlightí jet like a CJ2 or Phenom.
If you fly exclusively domestic USA on demand charters you will not encounter a lot of A380ís

You could have put your area of operations in your original post. Would have helped.
How about paying attention any time you hear Ďsuperí on your frequency.
Just the use of "ace" refutes the whole "legitimate".
Your "it must be in the USA if it is about flying" makes you the problem here, not the guy who asked the question. How about not assuming things you know nothing about...
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Old 14th Nov 2018, 17:57
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Hey B2N2, I donít think you are contributing in any way here guy.

I fly worldwide, including domestic US. Of course there is less of a chance to run into a 380 there, but you still could. Even if I wasnít doing the majority of my flight between the ME and Europe, I donít see why a legitimate question about the under-researched science of wake turbulence isnít warranted. The fact that you think all flying is about the US is just weird.
If I have 1, 20 or 40 years under my belt shouldnít matter either.
Frankly your sarky comment about European training says a lot about you.

Finally, I do pay attention when I hear Super on the radio. Doesnít really mitigate the risk though does it? But how would you know since your area of operation is 380-free?

Yours sincerely Ace

Thanks for your input Airmann, Xanda, Hans Brinker
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Old 14th Nov 2018, 21:03
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Originally Posted by sierra_mike View Post
i hear that call quite frequently in europe. e.g. "you are crossing x miles behind an a380, can you accept that?"
Ok never heard that.


But nevertheless shouldn't be left to the pilots should it? Good to ask, but like the original poster said, would be better if there was some concrete figures. They don't ask the pilot about seperation anywhere else, it is what it is and the ATC enforces it.
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Old 14th Nov 2018, 21:13
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Originally Posted by B2N2 View Post
If you fly exclusively domestic USA on demand charters you will not encounter a lot of A380ís
Exactly why ATC should be more careful. 380s aren't that common in most parts of the world, so when one does show up ATC should be there to protect the rest of the guys.

Anyone trying to gain more experience is great. Shame that most people only come on here to bitch and moan. PPRuNe is an amazing tool, to be able to ask people that have more knowledge than you is great, especially when certain information isn't available within your operation. I know that I'm a better pilot for it.
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