It looks like you're using an Ad Blocker.

Please white-list or disable AboveTopSecret.com in your ad-blocking tool.

Thank you.

 

Some features of ATS will be disabled while you continue to use an ad-blocker.

 

Deadly plane crash at Tokyo airport

page: 3
1
<< 1  2    4 >>

log in

join
share:

posted on Mar, 23 2009 @ 09:46 AM
link   
zaph i think your mistaking it for the in flight slat deployment which was corrected




posted on Mar, 23 2009 @ 09:52 AM
link   

Originally posted by Harlequin
zaph i think your mistaking it for the in flight slat deployment which was corrected


Yeah, you're right. Lack of sleep and job hunting at the same time is catching up to me.



posted on Mar, 23 2009 @ 09:53 AM
link   
reply to post by Zaphod58
 


Zaph....so, the spoiler handle is different?? 'cause on the DC-10, it was a T-handle with a trigger you pull up to get past the gate, and move aft to deploy. (BTW, you wrote 'slats'....different system
) EDIT....Harlequinl, ya beat me!

DC-10, arming AGS (or just auto spoilers....) was simply pulling straight up, there was a magnetic latch to hold it in the 'armed' position.

maybe the MD-11 will automatically retract the spoilers in a bounce??? The DC-10 would retract automatically with throttle movement towards go-around thrust....
(don't quote me on that, it's been 15 years since I flew the DC-10)

Anyway, it's safe to say that a lot can happen very quickly....just look at the timeline of the EWR accident as noted up above.

I think (and I was prone to it too) there is a certain mindset in pilots that after beginning the flare, you are committed to land. Perhaps it's ego....


[edit on 3/23/0909 by weedwhacker]



posted on Mar, 23 2009 @ 09:58 AM
link   

Zaph....so, the spoiler handle is different?? 'cause on the DC-10, it was a T-handle with a trigger you pull up to get past the gate, and move aft to deploy. (BTW, you wrote 'slats'....different system) EDIT....Harlequinl, ya beat me!

Yes, it is the same in the Md-11, with throttle movement they retract also.

I'm going to bed. I'll post again tomorow...

[edit on 23/3/2009 by C0bzz]



posted on Mar, 23 2009 @ 10:07 AM
link   

Originally posted by weedwhacker
Zaph....so, the spoiler handle is different?? 'cause on the DC-10, it was a T-handle with a trigger you pull up to get past the gate, and move aft to deploy. (BTW, you wrote 'slats'....different system
) EDIT....Harlequinl, ya beat me!


Not enough sleep last night, and stressing out over finding a job got to me this morning.
I read the post too fast, and read "spoiler" and brain said "slats". My bad.



posted on Mar, 23 2009 @ 10:37 AM
link   
reply to post by Harlequin
 


I was looking at those METARs and saw a lot of, what we here in the USA would call 'specials'....based on the time stamps.

Wind direction varied from 260 to 300 degrees...but, the trend isn't anything I haven't seen before, considering the cloud conditions (mostly clear). Sounds like a fast-approaching cold front....

One thing that will be examined is going to be their 'bug' speed for the approach. Our procedure was to ALWAYS add at least 5Knots above 'ref' in calm conditions, and then one-half the steady-state and all of the gust, up to a maximum of 20Knots.

the 'classic' notion of windshear usually involves something known as a microburst, and is associated with nearby CumuloNimbus. In clear air, near the ground, varying winds changing velocity and direction should be negotiable with a +20Knot additive to one's airspeed.

I've been to Narita....the Runways are not short, so a little excess airspeed is not an issue involved in landing distance...in fact, it can be your friend.

Of course, as pointed out, I flew the DC-10, not the MD-11...the MD-11 is fitted with the LSAS (Longitudinal Stability Augmentation System) that is basically a computer program that is designed to increase fuel effiency at cruise, as I understand it, by reducing induced drag from the Horizontal Stabilizer, as the C/G changes during fuel burn-off.

Any MD-11 pilots who could chime in? Is the LSAS "on" all of the time, is it 'passive' in the sense that it lurks in the background???

I know someone mentioned the software has been re-written a few times.



posted on Mar, 23 2009 @ 10:55 AM
link   
reply to post by Harlequin
 


Not replying to Harlequin, per se....

I thought I'd decode the METAR for others who wish to kknow what it says.

Taking the one Harleguin highlighted:

RJAA -- That is the ICAO (international) four-letter code for Narita, Japan.

222230Z -- That is the twenty-second day of the month, at 2230 Zulu (or, UTC)

30019G32KT -- Wind direction from 300 degrees, AT 19 gusting to 32 Knots

"9999"....is the visibility portion....this indicates there is no limit to visibility.

FEW030 -- Few clouds at 3,000 AGL (above ground level)

12/M03 Q1002 -- First, temperature and dewpoint, in Celsius. 'Q' is the barometric altimeter setting, in this case, 10.02 millibars.

WS R34R RMK 1CU030 A2959 -- This indicates that a 'windshear' was reported on the adjacent Runway, 34R. (This may be an older report, and it is common for the varying wind speeds and directions....it is meant as a general warning, a 'heads-up', if you will...)

'RMK'....'remarks'...."1CU030" ... ten percent comverage of cumulous clouds at 3,000 feet.

The 'A2959'.....that one I'm rusty on....I think it's the same as QNH in millibars (10.02) converted to the USA standard in inches of mercury (29.59 inches).

A 'standard' altimeter setting, at MSL, 59degreesF/15degreesC is 10.13 Mb, or 29.92 in/Mg.

Hope this helps.....



posted on Mar, 23 2009 @ 01:26 PM
link   
Watch the first video on this link. This is another FedEx MD-11 making a crosswind landing at the same airport back in February.

www.flightglobal.com...

They're also reporting wind gusts were up to 50mph at the time of the accident.

[edit on 3/23/2009 by Zaphod58]



posted on Mar, 23 2009 @ 02:43 PM
link   
reply to post by Zaphod58
 


Welll...your first video shows how it should be done!!

'crabbing' down Final....of course.

( in this case it seemed the crosswind was from the right... )

At roughly 100 feet, to 50 feet, my technique was to gradually transition from a crab to a sidelslip, into the crosswind. Rudder and aileron, to align the fuselage for the touchdown. (Right crosswind, left rudder, right aileron...). Upwind wing INTO the crosswind.....

Constant corrections all the way, of course....

On the DC-10, at about the 30-foot RA call, we began to reduce thrust to Flight Idle....again, it is technique....and judgement.

Because, at touch-down, you want the throttles at Flight Idle, in order to pull 'reverse'....all the while, if something doesn't 'feel right', then hit TO/GA and go-around!!!

The A/T are usually 'clicked off' by this point, in the flare....so TO/GA really gives you the pitch and roll bars on the AI, and slews the bugs on the N1 guages....YOU have to manually add thrust, call for a 'check' of thrust by the NFP, and follow the guidance on the Flight Director.

All the while calling the coll-outs for a normal 'missed-approach'....as Irecall, it was "TOGA", "Flaps 30, positive rate, gear up, check missed approach altitude" (which should have already been set in the MCP, or, as they call it, the 'FCP'....same concept, different terms.

Flaps are cleaned up 'on schedule'....not to exceed the limits....

(these are standards that should be practiced....as they are all to infrequently, sometimes, in the Simulator Environment.....)

A Go-Around that may entail a return for landing at the same Airport....if you consider it a possibility....you may stop your 'clean-up' at an intermediate flap setting....15 is good for the DC-10/MD-11.....as you maneuver for another approach.

This was a situation I found myself in once, while the F/O was flying into LAS (KLAS). The airplane ahead of us didn't clear the Runway....took their own sweet time...(was our OWN Company!!!)...but, anyway, the Tower told us to go around. (See, the decision to go-around can be made by ATC, or the PIC...)

Anyway, my F/O froze....even though I had been mentioning, all down the Final, that we might have to go around....and I told her to review the procedure, in her mind, just in case....well....I turned into Mr. Flight Instructor, once the Tower said to Go-Around.....

We were, of course, landing on 25L at KLAS....CAVU day....so we just made a left-pattern for 19L. My poor F/O was terrorized....I said, gently....ermm....you can re-engage the AutoPilot....that helped.

Still....I'd better stop posting, before I reveal too much.....and stray off-topic.....



posted on Mar, 23 2009 @ 11:44 PM
link   

Any MD-11 pilots who could chime in? Is the LSAS "on" all of the time, is it 'passive' in the sense that it lurks in the background???


LSAS is always on unless the autopilot is engaged, or when the aircraft is below 100 feet AGL. Includes Pitch attitude hold, pitch attitude limiting, pitch rate dampening, automatic pitch trim, speed protection, stall protection, and stability enhancement.

FYI, max crosswind for the md-11 is 35 knots.

Here's a nice PDF.

www.cad.gov.hk...

Designed for maximum sink rate of 10 feet per second, on a symmetrical landing. That's minimum required for certification, thus I expect it to be maximum expected load. Ultimate load would probably be 50% higher, or 12.3 feet per second.

Md-11 has three main gear, the left and right have four tires, the centre has two; total of 10. Thus L/R gear each probably would take 40% of the load on landing, assuming tire loading is equally distributed among the mains.


  • 10^2 = 100
  • 12.3^2 = 150
  • 7.74^2 = 60


So I guess on an asymmetrical landing on one main could be maximum of 7.74 feet per second, or, 464 feet per minute, asssuming all gear are the same strength for the load per unit of load they are designed to take. More than that I guess possibility of main wing spar failing. According to an MD-11 pilot, maximum landing is about 2.25g, above which requires inspection, but without knowing how fast the energy is absorbed I cannot see how much g 450fpm will result in.

Would be nice if the design failed in such a way where the gear would be pushed through the wing instead of it being snapped off. Like the 777.

Speculation and assumptions of course.


Some quotes from PPRUNE.

>> I flew this airplane for a number of years and it can be a real handful to land. There is more 'info' on landing technique than on any other aircraft I've ever flown. If you don't get it exactly right the nose wants to come down rather violently, causing a natural tendency to overcontrol and the nose then pitches up severely. (Part of it is due to where the CG is in relation to the main gear) Add strong gusty crosswinds and this beast can put your heart in your mouth. It looks like there was an attempt to recover from that first overreaction and then the nose hits hard-- after that all bets are off. I noticed that the nosegear had not sheared off from 1 of the pix, so that 'bounce/pitchover' might have happened here at the wrong time.


>> It is a real handful in a crosswind, especially gusty conditions as per the HKG accident.

I have over 7000 hours flying this type so here is some information on what happens during the landing of the MD-11.

After moving off the MD-11 fleet, there was an update to the LSAS and the corresponding software (cant remember all the details as I am not an engineer) which made an input to the elevator, so as to avoid tail strikes near the flare and main wheel touchdown. This input applied "nose down" elevator which was not evident to the crew in terms of "feel" on the control column.

The autothrottle is "full time" to 50 Feet RA when it will start to retard. It was long felt by seasoned crew that this height was too "high" for this to occur. The need to "override" the A/T in gusty conditions made for a better touch down. Keep in mind that the Md-11 at near MLW will achieve a descent rate of about 1100-1200 FPM in steady wind conditions.

For the descent rate to be "arrested" near the flare point, is the hardest item to be trained during line operations.

On touch down the ground spoilers will only partially deploy, which produces a "pitch up" moment. Until the software update and even after the deployment of the update, the pilot flying had to apply some forward control column pressure so as to stop the pitch up moment, which could easliy strike the number 3 VHF aerial at the bottom of the rear fuselage. When the nose gear was lowered to the runway, the ground spoilers then fully extended with subsequent tail engine reverse thrust now being made available (sleeves will not translate fully until nose gear touchdown) Only the wing mounted engines are able to use full reverse thrust with or without nose wheel touch down.

>>Without wanting to judge, just to provide additional information: Boeing MD-11 FCOM vol 2 procedures and techniques PT30.2:
Bounced Landing Recovery
If the aircraft should bounce, hold or re-establish a normal landing attitude
and add thrust as necessary to control the rate of descent. Avoid rapid
pitch rates in establishing a normal landing attitude.
CAUTION: Tail strikes or nosewheel structural damage can
occur if large forward or aft control column movements
are made prior to touchdown.
When a bounced landing occurs, consider initiating a go-around by use of
normal go-around procedures. Do not retract the landing gear until a
positive rate of climb is established because a second touchdown may
occur during the go-around.
I've been flying the MD-11 for more than 10 years and must say the FCC update has made the aircraft more stable. Luckily I've never found myself having to recover from such a bounced landing as seen in the video. Certainly, the MD-11 may not have the greatest elevator authority. But I expect it may be able to hold a landing attitude as well as other large transport category aircraft. I'm wondering however how g forces during the bounce will affect the pilots ability to "hold it steady" though. Hopefully we will all be able to learn from data from the FDR.

Also from FCOM3:
Longitudinal Stability Augmentation System (LSAS)
The Longitudinal Stability Augmentation System (LSAS) enhances longitudinal
stability and provides:
• Pitch attitude hold.
• Pitch attitude limiting.
• Pitch rate damping.
• Pitch attitude protection.
• Positive nose lowering.
• Speed limiting.
• Stall protection.
Each FCC contains two LSAS control channels. This provides four redundant
channels of control. LSAS operates through series control of the elevators (no
movement of control column), and is inhibited when autopilot is engaged.
With less than 2 pounds of force applied on the control column, LSAS holds pitch
attitude by deflecting the elevators up to +/-5°. LSAS provides automatic
horizontal stabilizer trim to off load steady-state elevator displacement, restoring
a full 5° of elevator authority. Whenever there is more than 2 pounds of force on
the control column, pitch attitude hold function is inhibited and the aircraft rotates
in proportion to the applied force. When force is then removed from the column,
the aircraft holds the new pitch attitude. Pitch attitude hold is inhibited at bank
angles exceeding 30° or below 100 feet RA.
Pitch Attitude Limiting (PAL) ensures that LSAS will only hold a pitch attitude
between 30° ANU and 10° AND.
Pitch Rate Damping (PRD) increases the apparent static stability to reduce the
chance of overcontrol in pitch, especially at high altitudes. It is active throughout
the flight envelope, below 16,500 feet at 30% of the maximum damping
(FCC-908) increasing linearly to 100% above 20,000 feet.
Pitch Attitude Protection (PAP)(FCC-908) reduces the chance of a tail strike
during take-off and landing by adding nose down elevator if the aircraft is at
serious risk of tail contact with the ground. PAP is a direct function of pitch
attitude, radio altitude and pitch rate and is enabled below 100 feet RA. The pitch
attitude limit will vary linearly from 30° at 40 feet RA to 9.5° at 0 feet RA.
Positive Nose Lowering (PNL)(FCC-908) will apply 3° of nose-down elevator
command when the FCC commands the Auto Ground Spoilers to extend at main
wheel spinup. As the spoilers extend beyond 10°, PNL will increase the
nose-down elevator command to 4°. The command fades out when FD mode
cycles back to T/O, or if throttles are advanced for G/A.
During take-off and landing flight phases, when PAP or PNL is active,
approximately 10-15 pounds of force on the control column is required to override
LSAS.
Upon detecting a fault, both channels of one FCC shut down. After selecting both
failed channels off, the remaining FCC is armed to revert to single LSAS channel
operation should one of the two remaining LSAS channels fail. The remaining
LSAS channels will increase deflection 2-fold (4-fold deflection occurs
automatically in case of reversion to single elevator LSAS operation).

www.pprune.org...



Video of normal landing.

www.youtube.com...

Can really see elevators working hard... uh... LSAS trims the whole stab to prevent running out of elevator...

Plane that crashed...:
www.youtube.com...

Kind of eerie seeing it roll past like that.

[edit on 24/3/2009 by C0bzz]



posted on Mar, 24 2009 @ 07:28 AM
link   
About 4 minutes before the accident another plane reported windshear at 2000 feet. They've recovered the recorders and are looking at them.



posted on Mar, 24 2009 @ 08:12 AM
link   
I'm puzzled that they recommend the A/T be engaged, even when the AP is dis-engaged, during an approach. (Obviously, T/O and Climb, and intermediate level-offs, hand-flying with the A/T on is a good idea...and helps you pay more attention outside in a high traffic environment).

In the DC-10, A-300, B737, B-757/767 I find it counter-intuitive, though, for the approach. Perhaps the software is improved on the MD-11, but the potential for A/T response affecting the pitch inputs, thus requiring pilot reaction, thus affecting the A/T...seems a bad mix.

Guess I'm a little old-fashioned....

EDIT....might I say, just in case no one has yet....my heart goes out to those pilots, and their families. We analyze these events in order to prevent future occurences. It doesn't mean we're heartless....

[edit on 3/24/0909 by weedwhacker]



posted on Mar, 24 2009 @ 03:11 PM
link   

4. immediately following nosewheel touchdown the aircraft pitched up dramatically and the aircraft ballooned into the air again.

Note: the rate at which the nosewheel was lowered may have been a part of the cause of the pitch-up following nose oleo compression, and that pitch-up might also have been exacerbated by the automatic extension of the spoilers which, in this type, are renowned for producing a pitch-up moment;

5. Now the aircraft is airborne again. This ballooning following first touchdown might have been made worse by a sudden gust of wind, momentarily raising the airspeed. But if that were true, the spoilers would have been simultaneously destroying a lot of the lift, and producing considerable drag; so, as the gust died (if it did) the aircraft might have been at or below stalling speed;

6. then - and this is what leads to disaster - the nose drops and stays low until the nosewheel's impact with the runway. This happens either because of lack of elevator authority, or because the pilot flying was tempted into a classic pilot induced oscillation.

Note: there are no circumstances under which a pilot of any type should deliberately select a nose-down attitude at that point - if, indeed, pilot selection of the nose-down attitude is what actually happened. During ballooning following touchdown the nose MUST be held up (if the elevator authority allows it) and appropriate power applied, whether the crew are trying for a successful second touchdown or for a go-around.

7. finally the nosewheel hits the ground extremely hard and the nose instantly rebounds upward, the main gear touching the surface momentarily a fraction of a second later. Almost simultaneously, the aircraft begins its fatal bank to the left, from which recovery was impossible once the left wingtip had hit the ground.

Note: banking to the left is not what the forecast crosswind would have been expected to produce. Normally, especially in a swept-wing aircraft like this one, the upwind wing has a tendency to lift, but in this case it didn't. So the crosswind does not appear to be the critical factor here, although windshear is very likely to be one of the causal factors.

Source

Excellent analysis on Flight today.



posted on Mar, 24 2009 @ 03:25 PM
link   
reply to post by Zaphod58
 


I have some issues, with the notion of the NLG switch being activated....even if once, it should have been considered to be part of the entire software.

The 'Air/Ground' logic in the systems isn't that simple.....

Unless it is a systemic flaw in the MD-11 software.....oooh...I smell 'lawsuit'!!!!!



posted on Mar, 25 2009 @ 07:17 AM
link   
NLG switch?





Because a fuse [pin] in the vertical plane may not prevent substantial loads from entering the wing structure once the fuse has released, and because the review of historical data indicated that failure due to overload was most likely to occur as a result of high drag loads, a different approach was taken to assure fuel tank integrity for the high vertical load (above 2.0 g’s) condition. For vertical loads above 2.0 g’s, the [MLG] is not designed to separate from the wing. Instead, the landing gear and its back-up structure are designed to be very robust, i.e., they are designed to withstand significantly greater descent rates than the 12 fps (ultimate)
required per Part 25.723 (b). Analysis has indicated that for a maximum landing weight, typical-landing-configuration landing, the MD-11 [MLG] can withstand up to a 16.9 fps descent rate without bottoming the shock struts or failing its backup structure including the wing rear spar. Similarly, for a rolled landing (8 degrees one-wing-low attitude, with lift equal to aircraft weight), the landing gear can withstand up to 15 fps descent rate without bottoming the shock strut or failing its back-up structure including the wing rear spar. 57 For ‘fused’ aircraft the (remaining) energy of vertical descent would then be absorbed by flexing the low-side wing, or by some combination of exercising the high-side landing gear, and flexing the low-side wing. For some combinations of sink and roll rates the low-side gear may fuse (followed by the wing engine/nacelle) and the aircraft may ‘settle in’ on the remaining gear and the lowside wing without compromising fuel tank integrity. For higher sink and roll rates (or lower amounts of wing lift) the low-side wing may fail nonetheless, as a result
of exceeding its flexure (bending) limits.

63 The Boeing submission also noted that, according to simulations, “subsequent to the failure [of the spar web structure], the right wing twists substantially nose-down under the imposed loads. This twisting causes the right wing to ‘dump’ most of its lift and results in a sudden and substantial outboard motion of the right main gear bogie, caused by the fixed and folding landing gear side braces pivoting about their (common) attachment at the trap panel fitting attachment point.”


www.ntsb.gov...

link has information about md-11 handling characteristics and lsas...

15 FPS is 900 FPM...

in the past DC-10's have survived landing impacts 2.6 times energy of certification minimums...

also..

www.cad.gov.hk...

what severe turbulence is like...:

www.youtube.com...

(joke)

[edit on 25/3/2009 by C0bzz]



posted on Mar, 25 2009 @ 12:50 PM
link   
reply to post by C0bzz
 


NLG = Nose Landing Gear....the nosewheel.

When the oleo strut is compressed, a switch is closed, thus satisfying certain parts of the Air/Ground logic circuits....



posted on Mar, 25 2009 @ 01:19 PM
link   
If this is a repetitive occurance at this airport, perhaps they should consider re-aligning that runway so that it faces more directly into the most prevelant wind direction than continuing to let airplanes make these risky landings.

Or close down the freaking airport and build it somewhere else.

Cost is not a factor when it comes to preserving lives.

Tragic accident...that should not have happend.



Cheers!!!!



posted on Mar, 25 2009 @ 01:29 PM
link   
reply to post by RFBurns
 


Burns, you have it slightly backward. When airports are built, the Runway alignment is predicated on the most frequently recorded wind direction trends.

Passing fronts, and other weather phenomena will temporarily vary wind direction.

Besides, at many Major International Airports, there are multiple Runways, at various angles. (Not always....but just using an example)

There are also very complicated factors involving the flow of inbound and outbound air traffic.....

I suggest a peek at the 'Flighttracker' website, which will show you Arrival and Departure procedures, graphically, for various airports in the USA.



posted on Mar, 25 2009 @ 01:47 PM
link   
reply to post by weedwhacker
 


No need for me to do that, I know quite a bit about aviation.

Looking at one of the videos from a helicopter hovering over the airfield and runway, it doesnt look like there is any other runway that is facing towards the prevailing wind pattern encounterd at that airport. If there was, why wasnt the flight diverted to that runway...which is the standard practice..to have air traffic use the runway that faces the prevailing wind.

There is plenty of area on that airfield to put in another runway of same length, and at an angle towards that wind pattern. Obviously when that airpoort was built, there must have been a different wind pattern, but also obviously, that has changed...so unless they want to continue to risk people's lives, my suggestion is to either install another runway facing that new wind pattern, or relocate the airport.

I think to save lives, and lower the risks, the choice to address the problem is...obvious.


Cheers!!!!!



posted on Mar, 25 2009 @ 01:52 PM
link   
reply to post by RFBurns
 


Burns, I think you may have missed my point.

It is the general trend of the historic wind direction that defines how an Airport is built.

But, Mother Nature is fickle...hence, we learn how to Take-Off and Land in a crosswind situation, when needed.

Either that, or suspend all flight operations until the wind dies down....



new topics

top topics



 
1
<< 1  2    4 >>

log in

join