TriL1011Star
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Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 2:24 am

https://kdvr.com/2019/01/07/wind-gust-s ... er-at-dia/

Did someone forget to set the parking brake? I have never heard of this happening.
 
WPvsMW
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 3:03 am

Rampers failed to chock the landing gear. (My analysis)
 
GalaxyFlyer
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 3:44 am

Parking brake only holds until the accumulator bleeds down, maybe an hour.

GF
 
WPvsMW
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 4:04 am

GF, will the marshaller take a hit, or just the chock handlers?
Maybe a wingwalker was subbing for a chock handler?
Maybe the wingwalkers are the chock hanlders at WN.
https://asrs.arc.nasa.gov/publications/ ... 8_ramp.htm
 
GalaxyFlyer
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 4:16 am

Sometimes, in strong winds, the plane jumps the chocks.



Gf
 
WPvsMW
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 4:21 am

I did not know that.
 
747Whale
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 4:21 am

TriL1011Star wrote:

Did someone forget to set the parking brake? I have never heard of this happening.


I certainly have.

Aircraft aren't left with the parking brake set; it's set prior to chock insertion and released after insertion, and set prior to removal...and while holding during taxiing with engines running. Otherwise, that's what chocks are for.

I've seen aircraft jump chocks. I've seen a 747 blown into a hangar doing damage to both the airplane and the hangar. I've seen lighter aircraft moved, and considerable damage done to aircraft when moved or blown by wind.

An airplane is no match for a strong enough wind event. This is especially true of an airplane that's not well enough secured.
 
WPvsMW
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 4:23 am

Sounds like bigger chocks are needed if high winds are forecast. Borrow some B747 chocks?

Strong tailwind generates lift on the wings, plane jumps chocks?
 
747Whale
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 4:38 am

Triple chock. Especially if just one gear is chocked, a sideload on the fuselage and vertical stab can cause an airplane to turn and pivot on the gear like a fulcrum. Airplanes are usually chocked with some space between the chock and the tire, given that as weight is added, the chock can become compressed and difficult or impossible to remove. Chocks are often placed at angle, too. With some play between the wheel and the chock, the aircraft has the ability to move, and in some cases move the chock. I've seen some get bouncing and can jump the chock that way, especially on the nosegear, and an unpowered nosegear can be turned, quite easily if the steering bypass or disconnect separates the gear from the actuator, or if the linkage has been separated (depending on equipment). A side load on the airplane from wind can then turn the airplane, and the nosegear can be turned. Once it's turned, if the aircraft isn't chocked well, or has jumped a chock, the entire airplane can move.
 
Raventech
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 4:46 am

WPvsMW wrote:
Sounds like bigger chocks are needed if high winds are forecast. Borrow some B747 chocks?

Strong tailwind generates lift on the wings, plane jumps chocks?


I think it was more winds were perpendicular to the aircraft and the Vertical Stabilizer acted as a giant sail.

My amateur analysis of a low res photo. Very strong wind just hits the aircraft from the right side. Tail receives massive force from wind due to large surface area. Aircraft begins to twist putting force on front left main chock and rear right main chock. Torque from the wind on the tail was enough to overcome one of the chocks and the aircraft rotated about the other chock. nose chocks would be ineffective here as the twist is around the main gear so nose gear swung out sideways where chocks are best at resisting front/back forces.
 
WPvsMW
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 4:50 am

So... what's the preventive measure? Tiedowns? At least on the nose gear?
 
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fr8mech
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 5:04 am

WPvsMW wrote:
So... what's the preventive measure? Tiedowns? At least on the nose gear?


When we have a forecast, high wind event all the wheels are chocked, all the doors and cowls are closed, and all the equipment is moved out of the aircraft perimeter.

Now, that’s not always practical, especially on a full ramp, but we clear as much of the equipment as we can.

I recall a jumbo that had been defueled for weighing when some high winds came in off Jamaica Bay. Picked the nose of that aircraft up and brought the aircraft down on the entry stand. Tore a big gash in the fuselage between L1 & L2.

Another, more recent event: we had one of our MD11 tail docks get pushed around by a windstorm and slammed into the tail of a B757. Took a few weeks and a Boeing team to get it flying again.

Wind is no joke.


WPvsMW wrote:
Borrow some B747 chocks?


All our chocks are the same size.

WPvsMW wrote:
GF, will the marshaller take a hit, or just the chock handlers?
Maybe a wingwalker was subbing for a chock handler?
Maybe the wingwalkers are the chock hanlders at WN.
https://asrs.arc.nasa.gov/publications/ ... 8_ramp.htm


Unless they can determine the aircraft wasn’t properly “handled”, no one will take the hit.
Last edited by fr8mech on Tue Jan 08, 2019 5:08 am, edited 1 time in total.
When seconds count...the police are minutes away.
Unless it's expressly prohibited, it's allowed.
You are not entitled to a public safe space.
 
Raventech
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 5:06 am

WPvsMW wrote:
So... what's the preventive measure? Tiedowns? At least on the nose gear?


I very well may be wrong but I don't think most commercial aircraft are designed to be tied down during normal operations. If there wasn't negligence in how the chocks were setup then they might buy some larger chocks when time comes to replace them, but at some point the odds are so low of something happening that its still cheaper to pay the repair bill for a freak weather event than predict every possible extreme and plan for it as the norm.
 
WPvsMW
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 5:08 am

fr8mech, thanks. Do you do anything with the control surfaces, esp. the rudder?
 
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fr8mech
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 5:17 am

WPvsMW wrote:
fr8mech, thanks. Do you do anything with the control surfaces, esp. the rudder?


Nothing to do on them. Older aircraft have gust locks, like the DC8, but I don’t know of anything designed since the 70’s with a gust lock. Not saying there isn’t anything out there, but I haven’t worked on it.

The hydraulic actuators will act as snubbers. The control surface, primarily the rudder will move, but the actuators will prevent it from slamming side to side.
When seconds count...the police are minutes away.
Unless it's expressly prohibited, it's allowed.
You are not entitled to a public safe space.
 
WPvsMW
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 5:18 am

Raventech wrote:
WPvsMW wrote:
So... what's the preventive measure? Tiedowns? At least on the nose gear?


I very well may be wrong but I don't think most commercial aircraft are designed to be tied down during normal operations.


Agreed, but responding to an unusually high wind forecast is not normal ops. I know that civilian transport category a/c aren't normally tied down like light aircraft, but if there are ramp tiedown anchors, could it be done? In Asia, I've seen ramp equipment tied down to anchors. HKG, IIRC.
 
stratclub
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 6:11 am

WPvsMW wrote:
Rampers failed to chock the landing gear. (My analysis)


You win the prize. Many times I have scene ground personnel chock aircraft leaving a space between the wheels and the chocks. On any aircraft with hydraulic brakes, once the hydraulic pressure is switched off, the brake system will bleed off pressure. Jumping chocks is extremely rare if the chocks are set properly.
 
WPvsMW
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 6:16 am

Thanks, I donate the prize to charity. I should have written, "Rampers failed to chock the landing gear properly", or "Rampers failed to chock the landing gear in anticipation of high winds", meaning extra chocks, or even tight chocks. I cannot imagine no chocks... but all it would take on the nose gear is setting the chocks too loosely... wind will do the rest.
 
stratclub
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 6:31 am

It is hilarious that with these kind of operational error someone has to assume that blame needs to be placed on somebody. Life does not represent Jerry Springers version of it. Seriously, the aircraft moved because of high winds. The test shows you are the father.
 
WPvsMW
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 6:53 am

Repercussions on employees or not, the incident has to be detailed for the insurer to pay the claim. Personnel names will be in some version of the casualty report, probably not the version the insurer receives.
 
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Starlionblue
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 7:38 am

WPvsMW wrote:
Raventech wrote:
WPvsMW wrote:
So... what's the preventive measure? Tiedowns? At least on the nose gear?


I very well may be wrong but I don't think most commercial aircraft are designed to be tied down during normal operations.


Agreed, but responding to an unusually high wind forecast is not normal ops. I know that civilian transport category a/c aren't normally tied down like light aircraft, but if there are ramp tiedown anchors, could it be done? In Asia, I've seen ramp equipment tied down to anchors. HKG, IIRC.


Even parked 747s have been known to jump their chocks and move a couple of meters in typhoons.

stratclub wrote:
WPvsMW wrote:
Rampers failed to chock the landing gear. (My analysis)


You win the prize. Many times I have scene ground personnel chock aircraft leaving a space between the wheels and the chocks. On any aircraft with hydraulic brakes, once the hydraulic pressure is switched off, the brake system will bleed off pressure. Jumping chocks is extremely rare if the chocks are set properly.


Wouldn't you leave a bit of a space because once you fuel up the tires will expand horizontally a bit?

stratclub wrote:
It is hilarious that with these kind of operational error someone has to assume that blame needs to be placed on somebody. Life does not represent Jerry Springers version of it. Seriously, the aircraft moved because of high winds. The test shows you are the father.


Word.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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TOGA10
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 10:31 am

747Whale wrote:
TriL1011Star wrote:

Did someone forget to set the parking brake? I have never heard of this happening.


I certainly have.

Aircraft aren't left with the parking brake set; it's set prior to chock insertion and released after insertion, and set prior to removal...and while holding during taxiing with engines running. Otherwise, that's what chocks are for.

Not always, we leave the parking brake on after parking. On the A320, the accumulator maintains the pressure for at least 12 hours, according to the FCOM. Chocks will also be in place, in the rare event that the aircraft will not move again within those 12 hours. But we will use the parking brake whenever we shut the A/C down and leave it on when we close up at the end of the day. Might be different from operator to operator!
Love flying, hate the alarm at 3 in the morning, love watching the sun rise at 5:30. It's all about compromises.
 
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Starlionblue
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 11:03 am

TOGA10 wrote:
747Whale wrote:
TriL1011Star wrote:

Did someone forget to set the parking brake? I have never heard of this happening.


I certainly have.

Aircraft aren't left with the parking brake set; it's set prior to chock insertion and released after insertion, and set prior to removal...and while holding during taxiing with engines running. Otherwise, that's what chocks are for.

Not always, we leave the parking brake on after parking. On the A320, the accumulator maintains the pressure for at least 12 hours, according to the FCOM. Chocks will also be in place, in the rare event that the aircraft will not move again within those 12 hours. But we will use the parking brake whenever we shut the A/C down and leave it on when we close up at the end of the day. Might be different from operator to operator!



Same on the A330 and A350. The park brake is on when we leave the aircraft and on when we arrive. What happens in between is of course a mystery... :?:
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
stratclub
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 3:04 pm

"Wouldn't you leave a bit of a space because once you fuel up the tires will expand horizontally a bit?"


Generally you would. but I have seen chocks set at least a foot away from the tires. If you have a typhoon coming, it is in your best interest to set chocks close to the tires and run the hydraulic system to make sure the parking brake is set because over time, the hydraulic pressure will bleed down.
 
WPvsMW
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 7:22 pm

Question: If Airbus hydraulic accumulators take 12 hours to bleed down, and Boeing's take 1 hour, is that intentional, or do Airbus types use shore or battery power to maintain pressure?
 
GalaxyFlyer
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 9:10 pm

WPvsMW wrote:
Question: If Airbus hydraulic accumulators take 12 hours to bleed down, and Boeing's take 1 hour, is that intentional, or do Airbus types use shore or battery power to maintain pressure?


If you’re referring to my post, I was extrapolating from other types, not Boeing specific.

GF
 
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AirKevin
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Re: Wind pushes Southwest plane into equipment

Tue Jan 08, 2019 10:31 pm

747Whale wrote:
Airplanes are usually chocked with some space between the chock and the tire, given that as weight is added, the chock can become compressed and difficult or impossible to remove.

Been there, done that, and I've definitely had the issue of struggling to get the chock out. Only difference is I was only operating an 80,000-pound tractor-trailer, so I can only imagine how difficult it is to pull the chock out of a plane if it's wedged under the tire. At least with the truck, I can just get in, back up a few inches (forklift driving into the trailer somehow has the tendency to push it forwards even just slightly), and move the chock out of the way.
Captain Kevin
 
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litz
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Re: Wind pushes Southwest plane into equipment

Wed Jan 09, 2019 9:06 pm

GalaxyFlyer wrote:
Sometimes, in strong winds, the plane jumps the chocks.
Gf


And then the occasional one that spins a 360 on ice or in a tornado ... (ask St Louis about the latter)
 
GalaxyFlyer
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Re: Wind pushes Southwest plane into equipment

Fri Jan 11, 2019 1:15 am

To say nothing about what a tornado can do to a pair of C-5s. Altus AFB, ca 1988

GF
 
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DocLightning
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Re: Wind pushes Southwest plane into equipment

Fri Jan 11, 2019 2:09 am

You can see that the chocks are in place in the post-incident photo. My guess is that the aircraft was chocked but slid sideways out of them or jumped them (and then the rampers moved them to keep the aircraft from moving more). It's also possible that this occurred just before chocks were placed, but it says that pax were disembarking, so presumably, that wouldn't start until the chocks were placed.

Chocks can prevent a lot of problems, but they are not invincible.
-Doc Lightning-

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CYYTguy
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Re: Wind pushes Southwest plane into equipment

Fri Jan 11, 2019 2:47 am

GalaxyFlyer wrote:
Sometimes, in strong winds, the plane jumps the chocks.



Gf

On time back in the 90’s here in CYYT, I witnessed a C-130 jump ice chocks in high winds. It happens
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Apprentice
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Re: Wind pushes Southwest plane into equipment

Sun Jan 13, 2019 6:09 am

Hi: Again it has much to do with company.
When I worked with AOM/ AF, We have to shock a/c with 6ea items: 2ea in LH or RH nose landing gear's wheel
LH LG, 1ea in front of wheel # 1 and 1ea on wheel # 5 (rear side)
RH LG and another 2, also in front and rear of RH lg wheels # 4 and #8
Steering was armed (mechanical disconnect was restored), for plane to make some resistance to lateral forces.
All Surfaces were up

Rgds/ Reinaldo
“An4; IL18; IL6; Tu5; D10; MD11; MD83; B32; B34: B37; B744; B748; B752; B763; B772; B773; B77W; A320; A332; A333; A342; A343.
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B777LRF
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Re: Wind pushes Southwest plane into equipment

Sun Jan 13, 2019 1:51 pm

The manual will probably say something along the lines of "in high wind conditions, chock all wheels, remove all equipment outside aircraft turning circle and consider parking aircraft with nose into prevailing wind direction". Whilst the former is easy, the two latter may not be physically impossible. What it means is, that even if you followed the book to the extent possible, an accident may still happen. The insurance company will, however, place all emphasis on the last two instructions and point to the fact the airline chose not to move the aircraft to a secure location, where they could be implemented. The fact that's highly impractical is not really their concern.

Placing the blame on a ramp worker willy-nilly shows three things: 1) You don't understand what a non-punitive safety culture is, 2) you don't understand the dynamics of high winds and what's practically possible and 3) you've never conducted an incident investigation.
Signature. You just read one.

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