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Take Off In A Typhoon  
User currently offlineCapt.Fantastic From United States of America, joined Aug 1999, 719 posts, RR: 0
Posted (4 years 6 months 3 weeks 1 day 4 hours ago) and read 8893 times:

Have a look at this video clip. I have never seen a takeoff in such conditions - It is a 767 departing HKG in a typhoon I believe. Could someone kindly translate the description of this video, or at least give some more info -- Anyone know the airline? The crosswind must have been extremely strong, given aileron / spoiler displacement. wow!

http://www.youtube.com/watch?v=tWu2LGiACLs

21 replies: All unread, jump to last
 
User currently offlineswiftski From Australia, joined Dec 2006, 2701 posts, RR: 2
Reply 1, posted (4 years 6 months 3 weeks 1 day 3 hours ago) and read 8864 times:

Quoting Capt.Fantastic (Thread starter):
The crosswind must have been extremely strong, given aileron / spoiler displacement.

There are inboard and outboard double-slotted fowler flaps. The ailerons are neutral for most of the clip, which actually suggests not very much crosswind.


User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 2, posted (4 years 6 months 3 weeks 1 day 3 hours ago) and read 8812 times:

Damn that was rough. Didn't almost lift off until after the aiming points. Funny to see the spoilerons twitching so much.

Otherwise looked pretty standard to me, must have been a left crosswind hence the deflection on that wing, standard procedure for a plane in the ground is to "bank" into the wind.


User currently offlineHalophila From United States of America, joined Aug 2005, 646 posts, RR: 4
Reply 3, posted (4 years 6 months 3 weeks 1 day 3 hours ago) and read 8758 times:

I have to say that given the conditions, I would probably have asked to not fly that day at the gate. That looked horrendous. At the very least the airline would have had to have bought a new seat cover.

I remember the Singapore Airlines 747-400 accident in Taipei was taking off during a typhoon as well. I'm not saying that was involved in the accident, but wanted to say that its probably common operations.



Flown on 707, 717, 727, 732 733 734 735 73G 738 739 741 742 743 744 74SP 757 753 762 763 772 773 77W D10 DC9 M11 M80 M87
User currently offlineMSYPI7185 From United States of America, joined Oct 2007, 710 posts, RR: 0
Reply 4, posted (4 years 6 months 3 weeks 1 day ago) and read 8500 times:

Interesting video.

I do not think I would have wanted to be on that flight!! I thought they would never get off that runway, was making me nervous just watching the video.

As the old saying goes, if you have a long enough runway it will eventually fly.

MD


User currently offlineDocLightning From United States of America, joined Nov 2005, 19608 posts, RR: 58
Reply 5, posted (4 years 6 months 3 weeks 23 hours ago) and read 8379 times:

Quoting FLY2HMO (Reply 2):
Damn that was rough. Didn't almost lift off until after the aiming points. Funny to see the spoilerons twitching so much.

Why were they deployed before rotation?


User currently offlineGFFgold From Indonesia, joined Feb 2007, 443 posts, RR: 0
Reply 6, posted (4 years 6 months 3 weeks 22 hours ago) and read 8260 times:

Looks a bit rough, however pilots who operate long-term in typhoon prone regions usually have lots of experience dealing with such conditions. HKG experiences a lot of typhoon weather in the course of a year and I guess people learn to deal with it - though when conditions are really bad the airport shuts down. Similarly, pilots in Northern Canada routinely deal with snow and ice that would terrify your average CX jockey and those who fly in tropical monsoon conditions are used to landing in conditions that might be considered marginal elsewhere.

User currently offlinemotopolitico From United States of America, joined Dec 2005, 212 posts, RR: 0
Reply 7, posted (4 years 6 months 3 weeks 6 hours ago) and read 7485 times:

Was the pilot looking to actively kill lift until he had reached a certain groundspeed, so that the a/c wasn't forced off the ground prematurely by a gust? Is that the profile of a typhoon, gustiness? After rotation, it seems as though the control surfaces are oscillating wildly. Is this some form of PIO? How did the engines not get swamped? How did the a/c not glaze over into a sheet of ice as it climbed to altitude? That pilot had balls of solid rock.


Garbage stinks; trash don't!
User currently offlinespacecadet From United States of America, joined Sep 2001, 3625 posts, RR: 12
Reply 8, posted (4 years 6 months 3 weeks 6 hours ago) and read 7332 times:

A few years ago the 747 I was flying on from NRT-JFK took off at the tail end of a typhoon; it wasn't as bad as this but I know from that experience that typically the airports in typhoon-prone areas of the world only seem to close during the very worst of the storm. In this country you would never even think about taking off during a hurricane, but they do it in other parts of the world all the time. What's a little wind and rain?


I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
User currently offlineYYZALA From Canada, joined Nov 2009, 155 posts, RR: 0
Reply 9, posted (4 years 6 months 3 weeks 6 hours ago) and read 7195 times:

Quoting spacecadet (Reply 8):
In this country you would never even think about taking off during a hurricane, but they do it in other parts of the world all the time. What's a little wind and rain?

What a silly comment to make. Regardless of nationality, everyone wants to live. Pilots know the limitations of their aircraft and therefore will or will not take off based on those limitations. If all the performance values are in the clear, why not takeoff? Just because YOU don't deem it safe does not mean the flight is not safe.

P.S. The airline is Aeroflot. Has been posted and discussed many times.

[Edited 2010-02-14 17:19:03]

User currently offlineBlatantEcho From United States of America, joined Sep 2000, 1904 posts, RR: 1
Reply 10, posted (4 years 6 months 3 weeks 5 hours ago) and read 7000 times:

that's a great video!


They're not handing trophies out today
User currently offlineJBirdAV8r From United States of America, joined Jun 2001, 4489 posts, RR: 21
Reply 11, posted (4 years 6 months 3 weeks 5 hours ago) and read 6912 times:

Quoting DocLightning (Reply 5):
Why were they deployed before rotation?

In addition to being used as speedbrakes and for lift dump on touchdown, spoilers are often used in conjunction with ailerons to roll the aircraft.

Next time you fly commercially, watch the wings as you taxi to the runway. As the crew checks the flight controls, you'll generally notice at least a few of the spoilers come up with the ailerons.



I got my head checked--by a jumbo jet
User currently offlineJBirdAV8r From United States of America, joined Jun 2001, 4489 posts, RR: 21
Reply 12, posted (4 years 6 months 3 weeks 5 hours ago) and read 6850 times:

Quoting Halophila (Reply 3):
I have to say that given the conditions, I would probably have asked to not fly that day at the gate. That looked horrendous. At the very least the airline would have had to have bought a new seat cover.

I remember the Singapore Airlines 747-400 accident in Taipei was taking off during a typhoon as well. I'm not saying that was involved in the accident, but wanted to say that its probably common operations.

While typhoons and hurricanes sound terrifying in name, the bottom line is that they're still storm systems. Safe flights are made all the time around certain parts of these systems. The wind in that video may not have even exceeded 30kt...it's just very hard to tell in the video. Although I am intrigued by what seemed to be quite a long takeoff roll...but again, that doesn't mean anything negative in and of itself.

Typhoon conditions generally are not the "sole" reason for an aircraft accident. The SQ accident, IIRC, happened when the crew attempted takeoff on a closed runway. The typhoon was a contributing factor insofar as the rain was heavy and reduced visibility; still, the accident shouldn't have happened.



I got my head checked--by a jumbo jet
User currently offlineGimliGlider From Germany, joined Jun 2006, 90 posts, RR: 0
Reply 13, posted (4 years 6 months 3 weeks 5 hours ago) and read 6771 times:

Quoting motopolitico (Reply 7):
Was the pilot looking to actively kill lift until he had reached a certain groundspeed, so that the a/c wasn't forced off the ground prematurely by a gust? Is that the profile of a typhoon, gustiness? After rotation, it seems as though the control surfaces are oscillating wildly. Is this some form of PIO? How did the engines not get swamped?

When you're on the ground in just about everything from a 172 to a 767, SOP (and good judgment) is to hold ailerons into the wind on takeoff. As you accelerate, you slowly let out the input until you have no deflection at rotation. This, as you said, effectively 'kills lift' on the windward side.

The control surface movement is likely an attempt to correct for wind and turbulence. PIO is overcompensation or overcorrection, and it doesn't look like that's happening here.



"You could attach that to your house and still go 0-60 in 5 seconds..."
User currently offlineHotelDJRomeo From Canada, joined Dec 2009, 159 posts, RR: 0
Reply 14, posted (4 years 6 months 3 weeks 5 hours ago) and read 6620 times:

Quoting swiftski (Reply 1):
There are inboard and outboard double-slotted fowler flaps. The ailerons are neutral for most of the clip, which actually suggests not very much crosswind.

While flaps are partially extended for takeoff, the ailerons and in-flight spoliers are anything but neutral.

This graphic helps to illustrate the various control surfaces on a wing:



Quoting DocLightning (Reply 5):
Why were they deployed before rotation?

Crosswind correction.

When an aircraft is on the ground and being hit with a crosswind, the upwind wing will generate more lift than the downwind wing. Obviously you don't want the aircraft to roll during takeoff (or during roll-out after a landing), so by turning the ailerons into the wind it works to counteract the imbalanced lift casued by the crosswind. When the aircraft is moving slowly you may start with the ailerons all the way over into the wind; as it accelerates (i.e. headwind component increases) the amount of crosswind correction required decreases.

In the video posted the in-flight spoilers and aileron on the left wing are up, so we're looking at the up-wind (left) wing.

(PS: Conversely if you have a quartering tail-wind, you turn the ailerons away from the wind)



Roger, Roger. What's our vector, Victor?
User currently offlineavek00 From United States of America, joined Oct 2004, 4369 posts, RR: 19
Reply 15, posted (4 years 6 months 3 weeks 4 hours ago) and read 6581 times:

But for the lack of PTVs I thought the airline involved was SQ.




Live life to the fullest.
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 16, posted (4 years 6 months 3 weeks 4 hours ago) and read 6572 times:

Quoting swiftski (Reply 1):
The ailerons are neutral for most of the clip, which actually suggests not very much crosswind.

The left ailerons are in fact up.

Quoting swiftski (Reply 1):
The ailerons are neutral for most of the clip, which actually suggests not very much crosswind.

The left ailerons are up from the start of the video.

Quoting FLY2HMO (Reply 2):
Funny to see the spoilerons twitching so much.

They work in unisons with the ailerons.

Quoting DocLightning (Reply 5):
Why were they deployed before rotation?

Because the ailerons are up.

Quoting JBirdAV8r (Reply 11):
In addition to being used as speedbrakes and for lift dump on touchdown, spoilers are often used in conjunction with ailerons to roll the aircraft.

The ailerons on the left wing are up during the entire takeoff roll. When the flaps are extended the spoilers work in conjunction with the ailerons (up ailerons up spoilers/down ailerons down spoilers). At liftoff the ailerons and spoiler retract then modulate up and down through the remainder of the video. All the above indicate taking off in a very strong crosswind.

[Edited 2010-02-14 18:33:38]

User currently offlineZeke From Hong Kong, joined Dec 2006, 9041 posts, RR: 75
Reply 17, posted (4 years 6 months 3 weeks 4 hours ago) and read 6455 times:

Quoting Capt.Fantastic (Thread starter):
Could someone kindly translate the description of this video, or at least give some more info

Basically it says that the airport was closed, and 11 aircraft were given the option at pilots discretion to attempt a takeoff, 9 out of the 11 aircraft took off, 2 returned to the gate.

Quoting Capt.Fantastic (Thread starter):
Anyone know the airline?

My guess would be Aeroflot.

Quoting Capt.Fantastic (Thread starter):
The crosswind must have been extremely strong, given aileron / spoiler displacement. wow!

Yes, excessive, I would think it would have made a mess of the performance calculations.

Quoting swiftski (Reply 1):
The ailerons are neutral for most of the clip, which actually suggests not very much crosswind.

No.

Quoting Halophila (Reply 3):
I have to say that given the conditions, I would probably have asked to not fly that day at the gate.

Same, in fact our airline would have grounded all of our aircraft, diverted incoming aircraft, and delayed departures.

Quoting GFFgold (Reply 6):
Looks a bit rough, however pilots who operate long-term in typhoon prone regions usually have lots of experience dealing with such conditions. HKG experiences a lot of typhoon weather in the course of a year and I guess people learn to deal with it - though when conditions are really bad the airport shuts down.

HKG based pilots do have a lot of exposure to the seasonal conditions in HKG, and are also well aware of the low level windshear that gets generated around the airport with any significant wind over the surrounding terrain.

Quoting GFFgold (Reply 6):
Similarly, pilots in Northern Canada routinely deal with snow and ice that would terrify your average CX jockey and those who fly in tropical monsoon conditions are used to landing in conditions that might be considered marginal elsewhere.

Our minimas are the same for landing in snow or in heavy rain. CX pilots see their fair share of cold Wx in China, Japan, Europe, and North America.

Quoting GimliGlider (Reply 13):
When you're on the ground in just about everything from a 172 to a 767, SOP (and good judgment) is to hold ailerons into the wind on takeoff. As you accelerate, you slowly let out the input until you have no deflection at rotation. This, as you said, effectively 'kills lift' on the windward side.

Reduces, but i think the larger issue is the impact on takeoff performance. Those spoilers being extended the way they are I would think would invalidate any RTOW calculation.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 18, posted (4 years 6 months 3 weeks 4 hours ago) and read 6424 times:

Quoting 474218 (Reply 16):
They work in unisons with the ailerons.

I'm a CFII, I know lol.

Just never seen them move so furiously before.


User currently offlineAaron747 From Japan, joined Aug 2003, 8135 posts, RR: 26
Reply 19, posted (4 years 6 months 3 weeks 4 hours ago) and read 6386 times:

Quoting swiftski (Reply 1):
The ailerons are neutral for most of the clip, which actually suggests not very much crosswind.

Totally wrong. How can you say that? Even at rotation the ailerons still had around 5 degrees of deflection. And if there was minimal crosswind, why were such large control inputs needed immediately when airborne? Crazy.

Quoting Zeke (Reply 17):

Same, in fact our airline would have grounded all of our aircraft, diverted incoming aircraft, and delayed departures.

CX clearly has a commitment to safety with such measures. Obviously it's possible to depart safely in these conditions but is it advisable? No. Even with the 12,000 foot runways at VHHH, it's not worth the risk. With that kind of wind and driving rain, there are no guarantees for getting stopped on the runway easily no matter when in the roll the abort happens.

Quoting Zeke (Reply 17):
and are also well aware of the low level windshear that gets generated around the airport with any significant wind over the surrounding terrain.

That would be the greatest concern of mine as well, particularly if low level and surface winds were out of the S/SW. The visibility is poor in the video but I'm assuming from the ramp lights that this is a 25R departure?



If you need someone to blame / throw a rock in the air / you'll hit someone guilty
User currently offlineswiftski From Australia, joined Dec 2006, 2701 posts, RR: 2
Reply 20, posted (4 years 6 months 3 weeks 1 hour ago) and read 5932 times:

Quoting HotelDJRomeo (Reply 14):
While flaps are partially extended for takeoff, the ailerons and in-flight spoliers are anything but neutral.
Quoting 474218 (Reply 16):
The left ailerons are in fact up.
Quoting 474218 (Reply 16):
The left ailerons are up from the start of the video.
Quoting Zeke (Reply 17):
No.
Quoting Aaron747 (Reply 19):
Totally wrong. How can you say that?

I accept all of the above corrections!

I have watched again on my computer and you're all right. I was watching on my phone before.

Sorry all.


User currently offlineJBirdAV8r From United States of America, joined Jun 2001, 4489 posts, RR: 21
Reply 21, posted (4 years 6 months 2 weeks 6 days 17 hours ago) and read 5664 times:

Quoting 474218 (Reply 16):
The ailerons on the left wing are up during the entire takeoff roll. When the flaps are extended the spoilers work in conjunction with the ailerons (up ailerons up spoilers/down ailerons down spoilers). At liftoff the ailerons and spoiler retract then modulate up and down through the remainder of the video. All the above indicate taking off in a very strong crosswind.

...right, which is what I said...I just simplified it for the non-pilots/engineers...

"Down spoilers" is kind of a misnomer because most aircraft with spoilerons don't have a negative position. They just stay in the 0' position when the ailerons on their wing are deflected downward.

Interestingly in my experience spoilerons aren't dependent on flap position--obviously you may have a different experience on the 767. Generally at higher speeds they aren't needed to augment roll control either...



I got my head checked--by a jumbo jet
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