klemmi85 From Germany, joined Mar 2009, 209 posts, RR: 0 Posted (7 months 2 weeks 5 days 22 hours ago) and read 2688 times:
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.
Longhornmaniac From United States of America, joined Jun 2005, 3094 posts, RR: 48 Reply 1, posted (7 months 2 weeks 5 days 21 hours ago) and read 2658 times:
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.
sprout5199 From United States of America, joined Feb 2005, 1779 posts, RR: 2 Reply 2, posted (7 months 2 weeks 5 days 20 hours ago) and read 2636 times:
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.
klemmi85 From Germany, joined Mar 2009, 209 posts, RR: 0 Reply 4, posted (7 months 2 weeks 5 days 20 hours ago) and read 2612 times:
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?
Longhornmaniac From United States of America, joined Jun 2005, 3094 posts, RR: 48 Reply 5, posted (7 months 2 weeks 5 days 19 hours ago) and read 2582 times:
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.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 7, posted (7 months 2 weeks 5 days 12 hours ago) and read 2474 times:
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).
stratosphere From United States of America, joined Sep 2007, 1613 posts, RR: 4 Reply 8, posted (7 months 2 weeks 5 days 9 hours ago) and read 2415 times:
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 From Germany, joined Mar 2009, 209 posts, RR: 0 Reply 9, posted (7 months 2 weeks 5 days 9 hours ago) and read 2414 times:
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).
Starlionblue From Hong Kong, joined Feb 2004, 15868 posts, RR: 66 Reply 10, posted (7 months 2 weeks 5 days 4 hours ago) and read 2361 times:
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." - from Citadel by John Ringo
3rdGen From Bahrain, joined Jul 2011, 162 posts, RR: 0 Reply 11, posted (7 months 2 weeks 4 days 1 hour ago) and read 2120 times:
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.
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