cxsjr
Posts: 711
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Mad Cross Winds!

Wed Jul 27, 2005 5:06 am

How about sharing some shots of aircraft suffering bad crosswinds?

Captured this an MAN earlier in the year - how bad does it have to be before the pilot aborts?

The world is a book, those who do not travel read only one page ....
 
legacy135
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RE: Mad Cross Winds!

Wed Jul 27, 2005 5:13 am

Quoting Cxsjr (Thread starter):
aircraft suffering bad crosswinds

I would rather call this "aircraft suffering from bad crosswind handling" as the pilot is supposed to align the plane with the centerline. The landing gear is not build for an acceleration that comes sidewards...
 
ACDC8
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RE: Mad Cross Winds!

Wed Jul 27, 2005 5:21 am

I'm thinking that this is a good example of severe x-wind:
http://www.flightlevel350.com/viewer.php?id=116&rating=yes
A Grumpy German Is A Sauerkraut
 
cxsjr
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RE: Mad Cross Winds!

Wed Jul 27, 2005 5:36 am

Quoting Legacy135 (Reply 1):
The landing gear is not build for an acceleration that comes sidewards...

... perhaps I'll give flying PIA a miss then? No wonder the undercarriage bays emit so much clouds of crap if that's the way they land their aircraft!
The world is a book, those who do not travel read only one page ....
 
typhaerion
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RE: Mad Cross Winds!

Wed Jul 27, 2005 5:40 am

Quoting ACDC8 (Reply 2):
I'm thinking that this is a good example of severe x-wind:

I would also say that attributing to that missed approach is the fact that the pilot came in awful high and hot. I am not a pilot, but I would have to assume that attempting to land after about 2500-3500 feet of runway does not allow for enough landing distance. Though that plane was sure bucking in the wind. No doubt about that.
For some, the sky is the limit. For us, it is only the beginning... -- Jack Hunt
 
ACDC8
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RE: Mad Cross Winds!

Wed Jul 27, 2005 5:48 am

I've never flown anything larger then a Seneca myself, but as you can see he's really crabbing into the wind. Due to the plane being all over the place, that would leave me to believe he's crabbing and not side-slipping to loose altitude. I also couldn't imagine him coming in hot and high on the approach on a day like that. Keep in mind, I'm sure he's being bounced all over the ILS though, and really playing with the throttles (unless the auto throttles are armed). Oh what fun!  Smile Hope you enjoyed anyway!
A Grumpy German Is A Sauerkraut
 
legacy135
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RE: Mad Cross Winds!

Wed Jul 27, 2005 6:16 am

Quoting Typhaerion (Reply 4):
I would also say that attributing to that missed approach is the fact that the pilot came in awful high and hot. I am not a pilot, but I would have to assume that attempting to land after about 2500-3500 feet of runway does not allow for enough landing distance. Though that plane was sure bucking in the wind. No doubt about that.

As ACDC8 says, he wasn't really wrong in the beginning. The clue is, if you are dealing with wind, you need to add an extra to your approach speed. This normally is 1/2 of the headwind component and an extra for the gusts. There might be an upper limit to make sure nobody is going to add like 50 knots or whatever.

We handle it as follows:
Vapp = Vref + wind correction
Wind correction = 1/2 headwind + full gust (but maximum 20 kts)

Let's do an example to make it look easier for the non-pilots being with us:

Vref = 118kts
Wind: 16 kts, gusting 25 kts
So, the wind correction will be 1/2 headwind (in this case 8 kts) and the full gusts of 9 kts (25-16)
So: Vapp = Vref 118 Kts + 8 kts windfactor + 9 kts gusts = 133 kts

If the pilot goes with numbers in this or similar manner, nothing should go wrong. Use of autothrottle could result in a uncontrolled situation as they might not handle the crosswind and being always to late what could result in an overoscillation of the aircraft.

What can be seen very often, is pilots getting afraid once in the gusts and flying far to fast. One fact is, that the wind 1000ft above ground is approximately the double it is on ground. In severe condition the wind will have additional drag trough buildings, trees etc. what results in much less just over the runway. This can lead to situations as we can see the TAP A321 in, being over the runway but with just "any" speed. Unfortunately a plane does not land at "any" speed.

Airplanes are not really certified for crosswind. The limits we find in the manuals are demonstrated values. This does not mean that you can't handle more if you are able to... but sure, it could also be the opposite. On the other hand companies need to put their limits in their operations manuals and I have the feeling, the TAP flight was over that limit.

For a nice smooth landing the little bit of luck is always with as well. If it results in a smooth landing after such an approach as here in the video, this little bit is a little lot of luck. The landing is just as good as the approach was and this needs to be stabilized. So if the approach is a fight, the crew should consider the only safe action..... go around, do it again or divert to the alternate.

Cheers  Wink


Glossary:
Vapp= Approach speed
Vref= Reference speed for approach (Stall speed x 1,3 incl. 30 degrees of bank)
 
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Starlionblue
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RE: Mad Cross Winds!

Wed Jul 27, 2005 6:26 am

Here are some really windy approaches:
http://www.rosboch.net/various/landing_at_wellington.wmv
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
typhaerion
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RE: Mad Cross Winds!

Wed Jul 27, 2005 6:57 am

Quoting Legacy135 (Reply 6):

Thank you very much for that informative post!
For some, the sky is the limit. For us, it is only the beginning... -- Jack Hunt
 
cbphoto
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RE: Mad Cross Winds!

Wed Jul 27, 2005 7:46 am

Quote:
The landing gear is not build for an acceleration that comes sidewards...

This is not entirely true. Yes it is not good for an aircraft to ever sideload, but it is built to withstand sideloads and considerable ones at that. I am sure someone with a more technical backround then me can give you details, but I can tell you landing gears will not snap off or break due to a crosswind landing!

Quote:
I've never flown anything larger then a Seneca myself, but as you can see he's really crabbing into the wind. Due to the plane being all over the place, that would leave me to believe he's crabbing and not side-slipping to loose altitude.

Good observation, he is crabbing and not slide slipping, although large aircraft never really slideslip, they always crab!!

This topic has been discussed in length, but the picture you see at the top of the post is a usual crosswind landing, althought it might be a little harder then most, but surely nothing out of the usual!
ETOPS: Engines Turning or Passengers Swimming
 
ACDC8
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RE: Mad Cross Winds!

Wed Jul 27, 2005 9:14 am

Quoting Starlionblue (Reply 7):
Here are some really windy approaches:

Holy cow! Now that was fantastic! Thanx Starlion!
Is it just me or did that one Ansett BAe146 come down on his nose gear? And that last Dash 8 .....  eyepopping  ! WOW!
Just goes to show you how much fun being a pilot is.
A Grumpy German Is A Sauerkraut
 
roseflyer
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RE: Mad Cross Winds!

Wed Jul 27, 2005 9:25 am

Quoting ACDC8 (Reply 5):
he's crabbing and not side-slipping to loose altitude

Definitely a crab since a big jet is not certified to perform a slip. Slips cause an incredible amount of force on the airplane and with the long moment on a bigger plane, the stresses are too much. Also a jetliner pilot should never need to slip.

I only have experience flying Cessnas, but if that were a small plane, that picture is a clear indicator of why you leave the bank in all the way until touchdown when dealing with a crosswind. You bank into the wind, and always have to use the rudder to keep yourself in line with the runway. Although landing gear can handle side loads, you are supposed to land on only one main gear in a bank rather than side load both main landing gear. Is it the same on a big jet?
If you have never designed an airplane part before, let the real designers do the work!
 
PhilSquares
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RE: Mad Cross Winds!

Wed Jul 27, 2005 9:27 am

Quoting Legacy135 (Reply 1):
I would rather call this "aircraft suffering from bad crosswind handling" as the pilot is supposed to align the plane with the centerline. The landing gear is not build for an acceleration that comes sidewards...

Not quite true. On Boeings (and I can't remember about Airbus) landing in a crab is an acceptable technique. However, it is not the best for passenger comfort. So, the preferred technique is cross controlling (aileron into the wind and rudder to align the nose).

The landing gear are in fact stressed for landing in a crab.
Fly fast, live slow
 
legacy135
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RE: Mad Cross Winds!

Thu Jul 28, 2005 12:58 am

Quoting PhilSquares (Reply 12):
landing in a crab is an acceptable technique. However, it is not the best for passenger comfort

Would you call it "acceptable" or "good"? And what would you say about your tires?

Quoting PhilSquares (Reply 12):
The landing gear are in fact stressed for landing in a crab.

I guess you agree with me that we are just a little closer to brake it if we are not going to align the plane with the centerline.

If we are talking about severe conditions the goal is to bring everybody on ground without bringing somebody in danger, I do agree with you that it could be acceptable to "crab the brid in the runway" under this circumstances. But I guess if we end up in this situation, probably somewhat went wrong in an earlier stage of this flight.

If we do talk about normal operations I can't see any reasonable issue that justifies a crabbing landing. We stress the airframe much more, we use the tires times more than in a normal landing and directional control, once the nosewheel is touching isn't initially going where we want. Furthermore we are closer to brake something than if we do the technique as you describe it as well, hanging the aileron into the wind and aligning the nose with the pedal.

Can you agree  Wink ? I am quite sure, regarding your expierience you are going to show us all quite nice crosswind landings in a real Irish wind with ease.
 
jayspilot
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RE: Mad Cross Winds!

Thu Jul 28, 2005 4:46 am

A 777's landing gear actually pivots to make the jet fly sideways and land more into the wind while the wheels go straight. I know on other jets like the 747 where you can't lower a wing b/c you will drag either the 1 or 4 engine you are able to land with up to a 30 ish degree crab and the plane is stressed for it. Slightly different then a 172 Smile
 
CosmicCruiser
Posts: 2049
Joined: Tue Feb 22, 2005 3:01 am

RE: Mad Cross Winds!

Thu Jul 28, 2005 6:03 am

Quoting Cbphoto (Reply 9):
. I am sure someone with a more technical backround then me can give you details, but I can tell you landing gears will not snap off or break due to a crosswind landing!

ahem, remember the fedex MD-10 had the main strut fail because they hit in a crab.

Quoting Cbphoto (Reply 9):
he is crabbing and not slide slipping, although large aircraft never really slideslip, they always crab!!

see the above post. I'm not talking 747(I know it's capable) but every other large plane I've flown is never landed in a crab and you will bust a sim ride if you can't land it in a slip. end of story. This has been beat to death but I can say at fedex we sometimes use the FPA which shows drift to ensure 0 deg. crab during a x-wind ldg and any deviation from centerline is a critiqued item.
 
legacy135
Posts: 966
Joined: Sat May 14, 2005 11:06 pm

RE: Mad Cross Winds!

Thu Jul 28, 2005 6:30 am

Quoting CosmicCruiser (Reply 15):
see the above post. I'm not talking 747(I know it's capable) but every other large plane I've flown is never landed in a crab and you will bust a sim ride if you can't land it in a slip. end of story. This has been beat to death but I can say at fedex we sometimes use the FPA which shows drift to ensure 0 deg. crab during a x-wind ldg and any deviation from centerline is a critiqued item.

Thank you CosmicCruiser, I am glad to see somebody showing up who also feels a pain if they go to land this poor plane in a crab and try to tell us that it needs to be like that.
 
tribird1011
Posts: 197
Joined: Mon Mar 14, 2005 10:08 pm

RE: Mad Cross Winds!

Thu Jul 28, 2005 12:48 pm

Quoting Typhaerion (Reply 4):
I would also say that attributing to that missed approach is the fact that the pilot came in awful high and hot. I am not a pilot, but I would have to assume that attempting to land after about 2500-3500 feet of runway does not allow for enough landing distance.

LIS's RWY 21 has a long displaced threshold - not sure how much - but at least 1000 feet displaced - so that being the case, from the beginning of the pavement in, the pilot should be aiming to touch down at a minimum of 2000 feet (1000 feet to make the threshold, plus 1000 feet as touchdown point). As such, the pilot was not high at all - as to hot, it's hard to tell how fast he's going, but he's going at Vref plus all the previous mentioned corrections, so he is definitely faster than he would be on a normal approach.

Wonder waht the pax were thinking as the ground came closer, in what looked like to be an unstabilized approach.

gotta love x-winds though...

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