Wake vortices... a sterile danger?

[Ramapriya]

I was at a place today from where I had a nice, clear view of the Dubai
Airport runway all day long. For about 3 hours in the morning, and
another 2-hour period in the afternoon, a string of aircraft took off
virtually tailing one another. Most of them were A330s, and the rest
were 747s and A340s, with the odd A320 and 737.

Makes me ask you folk this... are wake vortex caveats for real? How do
you manage when in a queue of big jets?

Ramapriya
ayirpamarATgmailDOTcom

[Roger Long]

Think of them as being like invisible ropes trailing from the
wingtips. They are small so your chance of hitting one is small. If
you do however, the probability of death from the upset at such low
altitude is very high.

They do trail like ropes so staying above the flight path(s) is basic.
There are accounts of them hitting the ground and bouncing back up
again which could ruin your day if you went through one just before
you flare.

--

Roger Long



"Ramapriya" > wrote in message
oups.com...
>I was at a place today from where I had a nice, clear view of the
>Dubai
> Airport runway all day long. For about 3 hours in the morning, and
> another 2-hour period in the afternoon, a string of aircraft took
> off
> virtually tailing one another. Most of them were A330s, and the rest
> were 747s and A340s, with the odd A320 and 737.
>
> Makes me ask you folk this... are wake vortex caveats for real? How
> do
> you manage when in a queue of big jets?
>
> Ramapriya
> ayirpamarATgmailDOTcom
>

[Peter R.]

Ramapriya > wrote:

> How do you manage when in a queue of big jets?

When flying into and out of Boston Logan airport in a Bonanza and assuming
the weather is not low IFR, I request an early turnout away from the
descending wing tip vortices.

The big jets take a lot more runway than I do and normally climb a thousand
or so feet before turning, so when at a large airport where reality is that
ATC is not grant me a three minute hold for wake turbulence (instead, they
will move me out of the way and the three minute hold works out to more
like an hour wait while jet after jet departs), I lift off immediately -
short field takeoff - then with tower approval begin an early turnout away
from the runway.


--
Peter

[Tony]

fwiw, make that turn request upwind if you can.

[Tony]

fwiw, make that turn request upwind if you can.

[John Gaquin]

"Ramapriya" > wrote in message

>.... a string of aircraft took off
> virtually tailing one another. Most of them were A330s, and the rest
> were 747s and A340s, with the odd A320 and 737.
>
> Makes me ask you folk this... are wake vortex caveats for real?

Very real. But, when you say "tailing one another", how tight do you mean?
What was your estimate of the separation? 1 minute? 2 minutes? 30
seconds? 10 seconds? There is no hard wingtip or flap edge vortex until
the wing starts to generate substantial lift, and these vortices tend to
sink at about 500 fpm quite promptly. So a lot of similar performance
aircraft with 1 minute separation will mostly be climbing out above the
vortices from the craft in front.

[Jay Honeck]

> Makes me ask you folk this... are wake vortex caveats for real? How do
> you manage when in a queue of big jets?

If you're talking about programming a 777, I have no idea. I suspect
it's not as big a deal for them, as you observed.

If you're talking about flying a Spam Can *behind* a 777, then wake
vortex danger is VERY real. I've only run into it (literally!) once,
when I landed too close behind a C-130 in Albuquerque, and ended up in
a 60 degree bank on short final -- but that experience was enough of a
shock to make me very cautious behind big stuff.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Larry Dighera]

On 19 Dec 2005 12:29:17 -0800, "Jay Honeck" > wrote
in . com>::

>If you're talking about flying a Spam Can *behind* a 777, then wake
>vortex danger is VERY real.

http://www.ntsb.gov/ntsb/GenPDF.asp?id=LAX98FA210&rpt=fa

[John Gaquin]

"Jay Honeck" > wrote in message

>....danger is VERY real. ......ended up in
> a 60 degree bank on short final -- but that experience was enough of a
> shock to make me very cautious behind big stuff.

You bet. This is one of those things that everyone talks about, and is
true. Just about everyone has hit a wake or knows someone who has. My
education came on a beautiful spring day about 25 years ago when I was on
final on a visual to 9 at BOS behind a DC9. I abruptly rolled right to
about 120 degrees of bank, and about as abruptly rolled back left to
approximately level. I forget what I told the pax.

[Gig 601XL Builder]

"John Gaquin" > wrote in message
. ..
>
> "Jay Honeck" > wrote in message
>
>>....danger is VERY real. ......ended up in
>> a 60 degree bank on short final -- but that experience was enough of a
>> shock to make me very cautious behind big stuff.
>
> You bet. This is one of those things that everyone talks about, and is
> true. Just about everyone has hit a wake or knows someone who has. My
> education came on a beautiful spring day about 25 years ago when I was on
> final on a visual to 9 at BOS behind a DC9. I abruptly rolled right to
> about 120 degrees of bank, and about as abruptly rolled back left to
> approximately level. I forget what I told the pax.
>

You probably told them that the smell in the cabin was from a nearby
rendering plant.

[Tony]

For what it's worth, always land long behind heavy iron, and take off
well short of where they rotated.

[Kyle Boatright]

"Ramapriya" > wrote in message
oups.com...
>I was at a place today from where I had a nice, clear view of the Dubai
> Airport runway all day long. For about 3 hours in the morning, and
> another 2-hour period in the afternoon, a string of aircraft took off
> virtually tailing one another. Most of them were A330s, and the rest
> were 747s and A340s, with the odd A320 and 737.
>
> Makes me ask you folk this... are wake vortex caveats for real? How do
> you manage when in a queue of big jets?
>
> Ramapriya
> ayirpamarATgmailDOTcom

Wake vortices are very real and they can ruin your whole day if you let 'em.

I was standing right under the approach path at Lakeland Linder (during the
Sun N Fun fly-in) when a DC-9 landed. 20 seconds or so later, after the jet
noise faded, you could hear the vortices it left behind. It sounded like
someone was tearing apart a bedsheet the size of a football field. Then, the
vortices descended to ground level and whipped up twin horizontal tornados
of the fine grey sand they have down there. Tents flapped and towels shook
in the wind, and after a few more seconds it all faded away.

It was kind of spooky, but very impressive.

KB

[zatatime]

On 19 Dec 2005 09:24:44 -0800, "Ramapriya" >
wrote:

>I was at a place today from where I had a nice, clear view of the Dubai
>Airport runway all day long. For about 3 hours in the morning, and
>another 2-hour period in the afternoon, a string of aircraft took off
>virtually tailing one another. Most of them were A330s, and the rest
>were 747s and A340s, with the odd A320 and 737.
>
>Makes me ask you folk this... are wake vortex caveats for real? How do
>you manage when in a queue of big jets?
>
>Ramapriya
>ayirpamarATgmailDOTcom


As I'm sure many other posters will point out, they sure are for real.
Like sized aircraft are less susceptible to them than the small planes
are. The US has a rule where you can wait for up to 3 minutes (I
believe) for them to dissipate if taking off behind a large aircraft.
There are also approach path changes you can make to avoid the vortex
of a wing.

My primary instructor flew me through the vortex of a C-141 once to
show me how real they were. That experience was more than enough to
make me wary of them at all times.

HTH.
z

[Ramapriya]

John Gaquin wrote:
>
> when you say "tailing one another", how tight do you mean?
> What was your estimate of the separation? 1 minute? 2 minutes? 30
> seconds? 10 seconds? There is no hard wingtip or flap edge vortex until

1 minute.

[Peter R.]

Morgans > wrote:

> Wake vorticies from a small plane are felt while the small plane is making
> circles in the sky, they will often feel a sharp bump as they cross their
> own wake. Now multiply that by many times.

I once inadvertently crossed a B727 wake perpendicularly. It was like
slamming into a large pothole at speed in an automobile.

--
Peter

[Morgans]

"Roger Long" > wrote in message
...
> Think of them as being like invisible ropes trailing from the
> wingtips. They are small so your chance of hitting one is small. If
> you do however, the probability of death from the upset at such low
> altitude is very high.
>
> They do trail like ropes so staying above the flight path(s) is basic.
> There are accounts of them hitting the ground and bouncing back up
> again which could ruin your day if you went through one just before
> you flare.

To Roger:

Although the characterization of them as a rope is accurate in a way, I
don't think that is correct to say that they are small.

To Ramapriya:

I have seen pictures of a 747 going through the rising smoke of a brush, or
forest fire, and the circulation of the smoke very clearly showed the size
of the disturbance. The diameter of the circulation was perhaps half of the
747's wingspan, as close as perhaps 10 plane lengths behind it. It was
completely invisible, except for the smoke in the air.

Sometimes in periods of high humidity, there is a very thin, rope-like
circulation behind the plane. I liken it to the eye of the hurricane, and
the circulation of the hurricane and it's tropical force winds reach far out
from the center of the storm.

Wake vorticies from a small plane are felt while the small plane is making
circles in the sky, they will often feel a sharp bump as they cross their
own wake. Now multiply that by many times.

It is interesting to note that although the 747 is one of the largest
planes, it does not have the worst wake reputation. I believe it is the 757
that is said to have more powerful wake vorticies.

I do wonder how the new Airbus 380 will trail the vorticies? They say it
will be no worse, but of course they would say that. <g>
--
Jim in NC

[Morgans]

"Peter R." > wrote

> I once inadvertently crossed a B727 wake perpendicularly. It was like
> slamming into a large pothole at speed in an automobile.

So did you take it into the shop to get the front-end aligned? It surely
must have needed it, after that! <g>
--
Jim in NC

[Jay Honeck]

> I was standing right under the approach path at Lakeland Linder (during
> the Sun N Fun fly-in) when a DC-9 landed. 20 seconds or so later, after
> the jet noise faded, you could hear the vortices it left behind. It
> sounded like someone was tearing apart a bedsheet the size of a football
> field. Then, the vortices descended to ground level and whipped up twin
> horizontal tornados of the fine grey sand they have down there. Tents
> flapped and towels shook in the wind, and after a few more seconds it all
> faded away.

We used to watch airliners land at Milwaukee's Mitchell Field (now Mitchell
International). When the wind was right, you could park right beneath the
approach path, and they'd go right over our heads, maybe 100 feet off the
ground.

The ripping sound made by their wingtip vortices was really amazing, just as
you describe. They would swirl all around you, long after the plane was
gone.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Peter R.]

Morgans > wrote:

> So did you take it into the shop to get the front-end aligned? It surely
> must have needed it, after that! <g>

My jaw needed to be re-aligned after that bump.

--
Peter

[Roger Long]

"Morgans" > wrote

> Although the characterization of them as a rope is accurate in a
> way, I
> don't think that is correct to say that they are small.
>

It's the killer part that is small. You are right that the
disturbance extends much farther. The people who were scared, nearly
died, and lived to tell us about it hit that outer disturbance. Not
many have described hitting the rope in the middle. They are a lot
like tornadoes. Look how close the chasers get to the funnels where
they are pelted by debris but live. Then consider the devastation at
the center.

--

Roger Long

[[email protected]]

I fly John Wayne. Parrallel runways Always a crosswind. Jets +
Cessnas. Always a wake concern.

Early turn out into the wind. Land long. Take off short. Approach high
and steep. Lots of slips.

If on an ILS keep 1 dot into the wind and 1 dot high. Takes care of it.