klemmi85
Topic Author
Posts: 134
Joined: Tue Mar 10, 2009 8:08 pm

Is This Wake Turbulence Or "normal" Turbulence?

Mon Oct 01, 2012 4:25 pm

Hi there,
since I'm heading out in the same direction pretty soon, I did some searching around youtube and came across a flight departing from LHR with the aircraft being all smooth until after takeoff there's a rapid, violent looking and sudden jolting.

The uploader states it's wake turbulence from a departing company 777 in front of them, question is... is this true, is this really wake turbulence this flight goes through?

Because keeping in mind it seems to be an A321 I would guess that it rotates earlier than a 777, so I'd suspect it to fly over the T7 wake instead of through it, especially since wake descends downwards and doesn't gain altitude.

Can someone please clarify?

The video:
http://www.youtube.com/watch?v=O3FpB78DTjI

rgds
quit a.net 07/2016
 
Longhornmaniac
Posts: 2972
Joined: Wed Jun 15, 2005 2:33 pm

RE: Is This Wake Turbulence Or "normal" Turbulence?

Mon Oct 01, 2012 5:08 pm

Is it possible that the rate of climb on the heavy 777 was greater than that of the A321, so even though, the A321 got off the ground sooner, they wound up being overtaken vertically by the 777?

Not saying this is the case, and it seems unlikely a passenger would easily be able to identify regular CAT from wake turbulence, but there is certainly a scenario where it could've been.

Cheers,
Cameron
Cheers,
Cameron
 
sprout5199
Posts: 1681
Joined: Sat Feb 26, 2005 8:26 am

RE: Is This Wake Turbulence Or "normal" Turbulence?

Mon Oct 01, 2012 6:08 pm

Quoting klemmi85 (Thread starter):
Because keeping in mind it seems to be an A321 I would guess that it rotates earlier than a 777, so I'd suspect it to fly over the T7 wake instead of through it, especially since wake descends downwards and doesn't gain altitude.

But seeing the windsock,light wind right down the runway, the wake would have been blown back.

Dan in Jupiter
 
Ychocky
Posts: 128
Joined: Fri Jul 17, 2009 4:03 pm

RE: Is This Wake Turbulence Or "normal" Turbulence?

Mon Oct 01, 2012 6:26 pm

The FA doing the announcement didn't even skip a beat.
 
klemmi85
Topic Author
Posts: 134
Joined: Tue Mar 10, 2009 8:08 pm

RE: Is This Wake Turbulence Or "normal" Turbulence?

Mon Oct 01, 2012 6:45 pm

Quoting Longhornmaniac (Reply 1):
Is it possible that the rate of climb on the heavy 777 was greater than that of the A321, so even though, the A321 got off the ground sooner, they wound up being overtaken vertically by the 777?

Interesting thought... Around this time most of the 777 flights should go eastbound, right? So they're very likely very heavy to cover 11-14 hours of flying... what rate of climb could a 777 achieve with a reasonable TOW for such trips? I know these massive engines give a lot of thrust but can it outclimb a 321 loaded with fuel for just over an hour airtime?
quit a.net 07/2016
 
Longhornmaniac
Posts: 2972
Joined: Wed Jun 15, 2005 2:33 pm

RE: Is This Wake Turbulence Or "normal" Turbulence?

Mon Oct 01, 2012 7:29 pm

Quoting klemmi85 (Reply 4):
Interesting thought... Around this time most of the 777 flights should go eastbound, right? So they're very likely very heavy to cover 11-14 hours of flying... what rate of climb could a 777 achieve with a reasonable TOW for such trips? I know these massive engines give a lot of thrust but can it outclimb a 321 loaded with fuel for just over an hour airtime?

I had the same thought. Keep in mind, it's entirely possible that BA would not refuel in DUS (though if it is a RON, I'd be surprised if they didn't), which would then necessitate them carrying both legs of fuel. Also, with derated takeoffs and climbs, you never know.

There are also plenty of BA 777 flights going to the Middle East (I know BA 155 to CAI leaves in the early evening, and though this appears to be late evening given amount of light and time of year, I imagine there are others). A Middle East-bound 777 would be considerably lighter than a Far East-bound 777.

Cheers,
Cameron
Cheers,
Cameron
 
User avatar
Starlionblue
Posts: 17212
Joined: Fri Feb 27, 2004 9:54 pm

RE: Is This Wake Turbulence Or "normal" Turbulence?

Mon Oct 01, 2012 8:31 pm

A couple of factors speak for wake turbulence:
- Close to an airport, on what is probably a departure procedure.
- Sharp jolt and then nothing.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Is This Wake Turbulence Or "normal" Turbulence?

Tue Oct 02, 2012 2:32 am

Quoting klemmi85 (Thread starter):
Because keeping in mind it seems to be an A321 I would guess that it rotates earlier than a 777, so I'd suspect it to fly over the T7 wake instead of through it, especially since wake descends downwards and doesn't gain altitude.

Keep in mind that Airbus, by default, uses overspeed takeoffs to improve climb gradient. As a result, if you don't play with anything, any Airbus will use more runway before rotating than a Boeing using its default (which is a balanced field).

Weight may not have much to do with it.

Tom.
 
stratosphere
Posts: 1087
Joined: Sat Sep 22, 2007 12:45 pm

RE: Is This Wake Turbulence Or "normal" Turbulence?

Tue Oct 02, 2012 5:47 am

Quoting Starlionblue (Reply 6):
A couple of factors speak for wake turbulence:
- Close to an airport, on what is probably a departure procedure.
- Sharp jolt and then nothing.

Bingo! ...I had it happen a few times right near an airport when it was smooth then a violent jolt then nothing. Two come to mind for me had a UsAir F-28 coming into CLT in a turn we were rocked so hard the overhead bins came open. Then one time coming into MSP on NW on a DC-9. I fly a lot and I can pretty much tell if it is wake or something other than that.
 
klemmi85
Topic Author
Posts: 134
Joined: Tue Mar 10, 2009 8:08 pm

RE: Is This Wake Turbulence Or "normal" Turbulence?

Tue Oct 02, 2012 5:48 am

Quoting Longhornmaniac (Reply 5):
I had the same thought. Keep in mind, it's entirely possible that BA would not refuel in DUS (though if it is a RON, I'd be surprised if they didn't), which would then necessitate them carrying both legs of fuel. Also, with derated takeoffs and climbs, you never know.

Thanks for pointing that out, didn't know they did that. Is it because of fuel prices at their home base being cheaper than in DUS for example or is this done to allow the first outbound to LHR depart as fast as possible in the morning?

Quoting tdscanuck (Reply 7):
Keep in mind that Airbus, by default, uses overspeed takeoffs to improve climb gradient. As a result, if you don't play with anything, any Airbus will use more runway before rotating than a Boeing using its default (which is a balanced field).

Interesting insight, thank you.
quit a.net 07/2016
 
User avatar
Starlionblue
Posts: 17212
Joined: Fri Feb 27, 2004 9:54 pm

RE: Is This Wake Turbulence Or "normal" Turbulence?

Tue Oct 02, 2012 10:15 am

Quoting klemmi85 (Reply 9):
Is it because of fuel prices at their home base being cheaper than in DUS for example or is this done to allow the first outbound to LHR depart as fast as possible in the morning?

Fueling typically takes less time than boarding so sounds like a cost thing.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
User avatar
3rdGen
Posts: 285
Joined: Wed Jul 13, 2011 7:19 pm

RE: Is This Wake Turbulence Or "normal" Turbulence?

Wed Oct 03, 2012 1:39 pm

Firstly, Don't make assumptions about the 321 Climb rate vs. the 777. The 777 wing was built for its size, the 321 wing is built for a 320. The 321 has a notoriously small wing, so much so that its approach speeds are higher than most wide bodies and it is categorized as a class D aircraft (due to approach speed), where as the Wide-Bodies are usually Class C. The 321 does not climb well and I wouldn't be surprised if a 777 would beat it up to cruise, even at high take-off weights.

Secondly, remember that Wake Turbulence doesn't remain steady it blows around in the wind. And in most cases there's some factor of head wind into the direction of an aircraft's take-off. Hence even if the 321 lifted off at a point along the runway before of the 777 it might well have flown into wake turb that was created ahead of its position but that had blown back. However, as stated this is only the case if the climb rate is worse than the preceding aircraft.
لا اله الا الله محمد رسول الله

Who is online

Users browsing this forum: snowmann and 18 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos