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Gonzalo
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UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 1:19 am

Does anyone have any information ( or a picture of course !! ) ?

How damaged resulted this plane ?

Apparently the crew didn't notice that they had a tail strike.

http://www.avherald.com/h?article=45e927b2&opt=0

Rgds.
G.
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tb727
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 1:42 am

Quoting Gonzalo (Thread starter):
Apparently the crew didn't notice that they had a tail strike.

I think that's fairly common, you most likely won't know unless you looked on your post flight. I always check the tailskid before and after my leg, just to be sure who to blame!
Too lazy to work, too scared to steal!
 
as739x
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 2:06 am

Not the first time a 739 has had a tailstrike, and won't be the last.
"Some pilots avoid storm cells and some play connect the dots!"
 
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Gonzalo
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 2:59 am

Quoting as739x (Reply 2):
Not the first time a 739 has had a tailstrike,

IIRC I read somewhere that the A321 has the same problem of a more difficult handling of the aft section during take off and landing being longer than the A320.

Quoting tb727 (Reply 1):
I think that's fairly common, you most likely won't know unless you looked on your post flight. I always check the tail skid before and after my leg, just to be sure who to blame!

Would be so difficult to install some sort of sensor in the tail skid to inform the crew about a contact with the runway ? ( I know there are sensors capable of detecting and inform about sudden decelerations, I was familiarized with them at work in the past, but those were for trucks, not planes )

Rgds.
G.
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tb727
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 3:15 am

Quoting Gonzalo (Reply 3):
Would be so difficult to install some sort of sensor in the tail skid to inform the crew about a contact with the runway ?

Yeah I'm sure they could but it's for something that's such a rare occurrence I don't think it's ever been deemed necessary. That's what pre-flight and post-flight inspections are for, look and make sure the big parts are there.

Usually you probably won't even notice so why have another bell and whistle going off for it. If it was a bad strike, you are most likely going to know it and then you deal with it.
Too lazy to work, too scared to steal!
 
BMI727
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 3:20 am

Quoting as739x (Reply 2):
Not the first time a 739 has had a tailstrike, and won't be the last.

No kidding. Doing it in a -700 would be an achievement.
Why do Aerospace Engineering students have to turn things in on time?
 
71Zulu
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 4:17 am

I like the idea of an immediate alert system to the cockpit. AA had a tail strike at LAX in a 738 on take off a couple years ago hard enough to damage the aft pressure bulkhead but with the crew unaware. The FAs told the cockpit the airplane may have hit the runway on take off, but they continued all the way to YYZ anyway, unacceptable imho.

http://avherald.com/h?article=43cbc4f9/0000&opt=0
 
roseflyer
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 5:39 am

Quoting 71Zulu (Reply 6):
I like the idea of an immediate alert system to the cockpit. AA had a tail strike at LAX in a 738 on take off a couple years ago hard enough to damage the aft pressure bulkhead but with the crew unaware. The FAs told the cockpit the airplane may have hit the runway on take off, but they continued all the way to http://avherald.com/h?article=43cbc4f9/0000&opt=0

The 777 has tail strike indication that causes an alert in the flight deck and inhibits the plane from pressurizing. Tail strike on takeoff is why they have the indication. A tail strike on Landing should be found on walk around if not reported. Every pilot I know of checks the tailskid well since thy don't want to be blamed for a tail strike after their flight.

Narrowbodies don't have such a system since tail strike is more likely on landing. The 900Er does have a two position tail skid with a giant shock absorber.

[Edited 2013-03-02 21:43:07]
If you have never designed an airplane part before, let the real designers do the work!
 
phunc
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 11:00 am

Quoting Gonzalo (Reply 3):
IIRC I read somewhere that the A321 has the same problem of a more difficult handling of the aft section during take off and landing being longer than the A320.

I was on the jump-seat of an A321 a couple of years ago and the FO, who was PF, ballooned the aeroplane at about 5 feet for a considerable part of the flare (almost caused the 777 behind us to go around as we rolled out to the end of the runway!). When we were parked up and were chatting he said that it's tempting to pull the side stick back a bit to bleed off some energy in order to plant it on the deck but in a 321, it can be a bad move incase you clip the tail. To pull off the same manoeuvre in an A320 is more forgiving.

In my 5 years at that airline, we had 3 tail strikes on landing in the 321.
 
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flylku
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 12:47 pm

It i my understanding that, at least for takeoff, the 773 has a system that prevents (or makes it very difficult) to over rotate and cause a tail strike. What are the details of that system, does the 739 have it and does it have any influence on landings?
...are we there yet?
 
777fan
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 1:56 pm

Interesting thread, since I've always wondered why Boeing never attempted to modify the 737-800 and -900 series' landing gear to prevent the aircraft from sitting so "long and low." Yes, I'm aware that it'd require a significant amount of engineering beyond just the landing gear assembly, and yes, I'm sure they figured the number of tail strikes was so low that it was not worth the cost of a redesign. Still, it seems like it limits the angle of attack on take off or landing (not to mention power plant design options), something that could be problematic depending on the length of the runway, wind conditions, etc.

Too bad not every aircraft can sit as high as the 757!

777fan
DC-8 61/63/71 DC-9-30/50 MD-80/82/83 DC-10-10/30 MD-11 717 721/2 732/3/4/5/G/8/9 741/2/4 752 762/3 777 A306/319/20/33 AT
 
Boeing744
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 2:35 pm

Just a side question: are tail strikes more common upon rotation or landing?
 
richiemo
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 2:52 pm

777fan's comment about the 7378 and 7379 sitting so low is an interesting one. I never liked the look of those planes because they look silly riding so low (vs the elegance of the 757). But I figured it may have been an advantage to those planes from a luggage loading/unloading perspective to have the cargo doors so close to the ground. It seems too that the way the 7378 and 9 engines have to be squared off around the bottom so they don't scrape the ground.
 
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tb727
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 3:03 pm

Quoting Boeing744 (Reply 11):
Just a side question: are tail strikes more common upon rotation or landing?

I think I'd have to say on takeoff, at least on my equipment.
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Gonzalo
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 3:20 pm

Quoting phunc (Reply 8):
To pull off the same manoeuvre in an A320 is more forgiving.

Well, I agree, but I guess there are some exceptions to that rule :

http://www.youtube.com/watch?v=rWAt_44NGfE

 Wow!  

Rgds.
G.
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AA94
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 3:25 pm

Quoting richiemo (Reply 12):
I never liked the look of those planes because they look silly riding so low (vs the elegance of the 757).

I agree, but it's a preference thing. No aircraft will ever look as elegant as the 757 does in my book.

On a somewhat related note, does the A321 sit as low as the 739? From photos, it would appear that it's higher off the ground, but I wasn't totally sure.
 
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Polot
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 3:30 pm

Quoting AA94 (Reply 15):
On a somewhat related note, does the A321 sit as low as the 739? From photos, it would appear that it's higher off the ground, but I wasn't totally sure.

The A32X family (including the A321) all sit higher than the 737 family. That said the A321 is also about 8ft longer than the 739.
 
phunc
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 3:52 pm

Quoting Gonzalo (Reply 14):
Well, I agree, but I guess there are some exceptions to that rule

That's a belting video! Thanks for that. I've never seen it before.

What appears to have happened in that video is what caused our A321 tail strikes. When the main gear hit the deck, the spoilers deploy and cause the pitch up effect. Not catching it quick enough results in the strike. Imagine if that was a 321!
 
roseflyer
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RE: UA 737 900 Tail Strike At ORD

Sun Mar 03, 2013 4:19 pm

Quoting flylku (Reply 9):

It i my understanding that, at least for takeoff, the 773 has a system that prevents (or makes it very difficult) to over rotate and cause a tail strike. What are the details of that system, does the 739 have it and does it have any influence on landings?


The 773 has over rotation protection in the form of the flight control envelope protection. The 737NG has cable driven manual controls and no such protection.

Quoting 777fan (Reply 10):
Interesting thread, since I've always wondered why Boeing never attempted to modify the 737-800 and -900 series' landing gear to prevent the aircraft from sitting so "long and low." Yes, I'm aware that it'd require a significant amount of engineering beyond just the landing gear assembly, and yes, I'm sure they figured the number of tail strikes was so low that it was not worth the cost of a redesign. Still, it seems like it limits the angle of attack on take off or landing (not to mention power plant design options), something that could be problematic depending on the length of the runway, wind conditions, etc.

It would be expensive and cause a big weight penalty. Taller landing gear would weigh more which increases fuel burn. Also it would require new overwing slides and potentially decrease the evacuation capability which would reduce passenger count.

It sounds easy, but taller gear has consequences that are bigger than the risk of a tail strike. What Boeing did is add a two position tail skid with a shock absorber in case one happens. Also spoiler panels have increased deflection to improve stopping. The A321 has modified flaps. Gear height changes are almost always a last resort when stretching an airplane. Behind the scenes changes are often more effective overall.
If you have never designed an airplane part before, let the real designers do the work!
 
Valcory
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RE: UA 737 900 Tail Strike At ORD

Mon Mar 04, 2013 5:53 am

.

Quoting 71Zulu (Reply 6):
I like the idea of an immediate alert system to the cockpit. AA had a tail strike at LAX in a 738 on take off a couple years ago hard enough to damage the aft pressure bulkhead but with the crew unaware. The FAs told the cockpit the airplane may have hit the runway on take off, but they continued all the way to YYZ anyway, unacceptable imho.

The 757-300,767-300,767-400,777 have tail skid indication. You will get an EICAS tailskid message.
 
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b727fa
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RE: UA 737 900 Tail Strike At ORD

Mon Mar 04, 2013 6:03 am

Quoting Gonzalo (Thread starter):
Apparently the crew didn't notice that they had a tail strike.

What, the aircraft parts have unions now?!?!   
My comments/opinions are my own and are not to be construed as the opinion(s) of my employer.
 
rwessel
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RE: UA 737 900 Tail Strike At ORD

Mon Mar 04, 2013 7:29 am

Quoting 777fan (Reply 10):
Interesting thread, since I've always wondered why Boeing never attempted to modify the 737-800 and -900 series' landing gear to prevent the aircraft from sitting so "long and low." Yes, I'm aware that it'd require a significant amount of engineering beyond just the landing gear assembly, and yes, I'm sure they figured the number of tail strikes was so low that it was not worth the cost of a redesign. Still, it seems like it limits the angle of attack on take off or landing (not to mention power plant design options), something that could be problematic depending on the length of the runway, wind conditions, etc.

Boeing has vastly greater motivation than the rare tail strike to increase the gear height on the 737. They've spent immense effort getting high bypass engines to fit under the wings, and are at a disadvantage compared to the A320 in that area, where the A320 can easily take a rather larger fan. Boeing builds a very competitive aircraft, but the limited ground clearance is a huge pain.

But making the gear longer is difficult. Take a look at the inside of the gear bay:


View Large View Medium
Click here for bigger photo!

Photo © Yochai Mossi - AirTeamImages



The other main gear's well starts just below the center beam at the bottom of the picture. There is literally no room. You could move the gear mounts further out on the wing (a huge redesign effort to move what may be the most highly loaded and stressed point on the airframe), or do something to allow the gear to lengthen after being extended (it’s been done, but it’s heavy, complex, etc.), and anything you would do would require you to mess with that mass of stuff inside the gear well
 
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Gonzalo
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RE: UA 737 900 Tail Strike At ORD

Mon Mar 04, 2013 11:11 am

Quoting Boeing744 (Reply 11):
Just a side question: are tail strikes more common upon rotation or landing?

Well, statistically, the chances are probably 50 / 50 ( every aircraft *should* have one landing after every take off, and that makes the chances very similar ).

But apparently this last couple of days there are more problems at landing, now it was an Airbus 310 :

http://www.avherald.com/h?article=45e9be4d&opt=0

Quoting B727FA (Reply 26):
What, the aircraft parts have unions now?!?!

Good one. I think if that day comes, the first agitators will be the computers of the IB's planes !!      

G.
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dcajet
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RE: UA 737 900 Tail Strike At ORD

Mon Mar 04, 2013 4:14 pm

Quoting Gonzalo (Reply 29):
Good one. I think if that day comes, the first agitators will be the computers of the IB's planes !!

Sorry man, but that is not funny. And in poor taste. I am sure you have been taught not to make fun of the misfortunes of others. And exercising your constitutional right to strike does not make you an agitator.

Rgds,
Keep calm and wash your hands.
 
FlyDeltaJets
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RE: UA 737 900 Tail Strike At ORD

Mon Mar 04, 2013 7:37 pm

From what I read the crew encounted crosswinds and windshear on landing.
The only valid opinions are those based in facts
 
ordramper98
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RE: UA 737 900 Tail Strike At ORD

Tue Mar 05, 2013 2:22 am

Same airplane that was blown into a fuel truck in Buffalo not too long ago.
 
ADXMatt
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RE: UA 737 900 Tail Strike At ORD

Tue Mar 05, 2013 2:23 am

Seems to have some real damage to the A/C and showing out of service for at least ten more days.
 
tozairport
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RE: UA 737 900 Tail Strike At ORD

Tue Mar 05, 2013 6:45 am

United flight proudly operated by Continental pilots (just like CLE)...
Meet the new boss, same as the old boss.
 
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antoniemey
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RE: UA 737 900 Tail Strike At ORD

Tue Mar 05, 2013 9:29 am

Quoting ordramper98 (Reply 25):
Same airplane that was blown into a fuel truck in Buffalo not too long ago.

That plane's gonna get a reputation...

Quoting tozairport (Reply 27):
United flight proudly operated by Continental pilots (just like CLE)...

Not really sure what that's supposed to mean. Nor how it's relevant.
Make something Idiot-proof, and the Universe will make a more inept idiot.
 
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RyanairGuru
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RE: UA 737 900 Tail Strike At ORD

Tue Mar 05, 2013 9:35 am

Quoting antoniemey (Reply 28):
Not really sure what that's supposed to mean. Nor how it's relevant.

I think he is trying to suggest that professional, Real United pilots would never do something so amateurish, and that you can't trust these hicks in cowboy boots out of Texas  
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