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Touch 'n' oops,
The nosewheels didn't shear off. Both of the hubs are clearly still there on the axle. The tyres probably perished from the heat of the flames. |
Take your point re: the image - but the burnt wing remains are a couple of degrees forward of where they should be (straight leading edge)(camera angles/zooms etc taken as very variable). Which 'just might' be the case if the flailing sub-structures directed it to. Or, of course, maybe I'm wrong, and the position of the remains of the wing is due to all of the almost incalculable stresses it sustained.
However, if you watch the video as often as I have, you might understand why I have convinced myself that the outer wing panel rotates (in roll) faster than the fuselage and stbd engine? |
Right
I was extrapolating. The wing snapped loose, but remained attached. I refer to the post (#65). I had assumed it parted, evidently not. Thx.
AF Check the wing's remains, they look as if they've rotated front to back. the tip angle, flap structure, etc. "twisted" around the main spar. |
I suspect some of the posters who talk of the "right wing" being separated are stunningly unaware that the airplane is upside down. Ready, fire, aim...
Stephan Wilkinson |
Just a thought, if the initial NLG touchdown was sufficiently forceful, is it possible that any remaining control of the aircraft was lost at this point, pilots unable to respond to anything after initial touchdown rather than an attempted correction gone awry?
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Stepwilk
View the vid linked in #65. All the way to its conclusion.
AF |
Agreed. In that image, the Port wing is separated. The remains of the severely burnt Starboard wing are just dust towards the bottom of the picture. However, the pattern is about two or three degrees forward of where it should be. I'll say again. The camera angle makes it look that way, but who knows?
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FYI: From The Aviation Herald :-
The JTSB reported, that the flight data recorder and cockpit voice recorder have both been recovered, data analysis has started. The nose gear tires were found separated from the wheels supposedly departing the rims when the airplane touched down the second time with the nose gear first, the left wing broke off at the wing root at impact with the runway. The NTSB (USA) is joining the investigation with a go-team. |
Flightmech:
I know what you thought and so did I, but see the post before this one. Those are not the rims. Compare with this photo http://farm1.static.flickr.com/168/4...2972b1.jpg?v=0 |
Absolutely
The Md-11 and Dc-10 have bogies and a Center gear that are aft of the CG. Assuming, windshear advisory they were flying into a slight angled crosswind at 40kt they were 10 kt above calculated speed, windshear, overrotation and roll input to compensate driving the mlg and cg harder into the ground.
Followed by Loss of A/S, possible elevator input from a late reaction fatally driving the nose into the ground and a 2nd bounce off the mains, lost enough a/s to come down with the left wing stalled out (cross wind/ or W/S adding to the situation). I have experienced similar sucessfull landings in a DC-10-30 and a MD-11. Dc-10-30 F/O landing, below G/S. Attempts to compensate with a too late flare, heard 30 on the R.A callout the 2nd time around bouncing and landing hard in a 1 wing stall. Md-11, Windshear at 30 R.A., full aileron input to compensate no help, hard landing on one gear, allmost scraped the eng. |
The news this morning shows a large collection of machinery cleaning up the wreckage, evidently they are hoping to open the runway later today.
Dozens of flights are still being affected; many pax have been bussed to other airports. Kudos to the Narita Airport Authority, despite this being their first incident it seems they are coping very well with both the crash and its aftermath. |
"Am I right in thinking that the MD11 has a couple of features to assist in the lowering of the nose-wheel upon touch down?
-Ground spoilers deploy only initially to 45deg until the nose-wheel strut is compressed, then the spoiler handle continues to the 60deg (full position). -Engine 2 is limited to idle reverse until the nose-wheel strut is compressed. Is this correct?" The FCC's recieved a program correction years ago to drive the stab A.N.D. after the MLG is compressed to my knowledge years ago as a result of several tail strikes. The Md-11 is not an aircraft that is safe to perform "aerodynamic breaking" in because of the smaller horizontal stab. This could have had a slight influence. |
FCOM
Without wanting to judge, just to provide additional information: Boeing MD-11 FCOM vol 2 procedures and techniques PT30.2:
Bounced Landing Recovery 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. 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. Also from FCOM3: Longitudinal Stability Augmentation System (LSAS) Question is, what caused the nose lowering: pilot input or LSAS. In both cases things need to be changed.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). |
It will be interesting to see what the FDR makes of the speed over the fence. It looks fast and has the hallmark of mainwheels first, nose down to complete the landing by which time the mainwheels are off the ground again. The rest of the oscillation is down to science but there is a definite 'puff' when the nosewheels hit the second time, probably losing tyres and rims.
Fast over the fence could be for a number of reasons in those wind conditions. |
Burbank
I'd even go so far as too select out that whole section on PAP and and PNL for a good read - and feature the last paragraph. 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. |
Narita 16R/34L Open
Runway 16R/34L reported open from 9:10 am Japan time on the Japanese language webpage of Narita airport.
Rgds |
It is indeed open; I'm watching aircraft depart from 34L from my hotel room. I hope to be departing from it myself by tomorrow morning.
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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. |
Plane had 101,992 lbs of freight on board.
Leo |
Comparative crashes in different Forum sections)
News Shooter
I just want to understand the rules. Thanks for any help you can give me. We don't need rules, just judgements. It's kind of like news papers with sports sections and Financial sections. Sometimes the reader interest is so high that an item makes the front page headline. OTOH we have in the US Telly the 6 O'clock news and the news at 11 pm. If your really a local you watch both. Otherwise like me you just sample what's hot. So let the reader (browsers decide what's hot) and the Mods second guess us all :) |
Touch'n' oops,
Thanks for correcting me but I said hubs not rims. The hubs can clearly be seen along with tie bolts. The majority of the wheels are still bolted to the axle. Thanks for the photo, but I'm fully aware of what a DC-10/MD-11 nose tyre/wheel assy looks like thanks. |
I'm wondering how this impact compares with some other landing accidents. Someone mentioned the Iberia 340 at Quito(?) being 3g, but I would have thought the 777 at LHR would have been heavier, and possibly the Britannia in Girona. In the 777 case, one landing gear separated and the other went through the top of the wing - a much better outcome than the wing coming off and the aircraft rolling inverted. The Ryanair 737 in Ciampino also had the u/c partly go through the top of the wing.
Retraso.com, accidentes aereos, air disasters, air crashes, Aircrew Buzz: Ryanair Flight FR4102 Emergency at Rome-Ciampino: Multiple Bird Strikes In the Brittania case: "The aircraft, yawed considerably to the right of its direction of travel, then passed through the fence, re-landed in a field and both main landing gears collapsed. It came to rest after a 244 metre slide across the field, with the fuselage almost structurally severed at two points, the NLG and both engines detached and the underside of the left wing torque box split open near the wing root. The three fuselage parts remained upright, connected by cables, wires and other services, but rolled to the left between 8-16°. There was no fire". Just because the MD11 is certified to a certain structural limit (Xg) doesn't mean the wing should fall off when that structural limit gets to X.1g! |
I have a gut feeling that this MD11 experienced more than 3 G's....more than the quito Airbus.
Of course I'm patiently waiting for the final report, just like everyone else. But since someone mentioned pilot induced occilation, check this out: YouTube - Crazy landing with L-410 It shows what can happen with PIO. |
Someone mentioned the Iberia 340 at Quito(?) being 3g The 'G' that something experiences, will vary across the whole aircraft structure, and parts thereof, depending on it's mass, stiffness, interconnectedness and instantaneous crash dynamics. For instance, the recent AMS 737 accident, it is quite evident that the forward fuselage experienced many times the 'g' force of the centre fuselage and wing section. Ultimately it's the forces that count, which are dependent upon the mass of the part that's accelerated, which (mass) could of course change dramatically during the course of an accident... so any comments on what should and shouldn't break and how, is highly speculative. Granted though, that MD-10 & 11s seem to come apart pretty dramatically in such incidents... it would have been the accelarative forces of the flipping of the right wing, that seemed to break it outboard of the pylon. |
Intresting reviews on md-11
website where this was published:
That Tragic MD-11 Safety Record Subject: WSJ /Jet's Troubled History/continued Yet sometimes, at low altitude, the opposite occurs: Pilots tell of pulling with all their might and finding the plane hardly responded. That can be a problem during landing. In several instances where pilots brought down their MD-11s too rapidly and tried to compensate at the last minute, they smacked the aircraft's tail on the runway or caused other damage. That's what NTSB investigators reckoned took place in 1997 when FedEx pilots tried to land an MD-11 at Newark. The plane touched down too hard, bounced, rolled right, broke its right wing, flipped over and was destroyed by fire. The two pilots, who escaped, took most of the blame. But the safety board also raised questions about the plane's "stability and control characteristics," the design of its landing gear and why its wing broke off, a rare occurrence in similar hard-landing accidents. Boeing acknowledges the tail-strike problem but says it has addressed the matter in a variety of ways, including new software and better pilot-training programs. It says there hasn't been a serious MD-11 tail strike reported in the past year or so. 'Just Quit Flying' Veteran FedEx captain Jack Burke, who once walked away from an MD-11 tail strike, has described his caution about flying the plane. "The first 100 feet and the last 100 feet are where the crew really has to sweat it," he says. If the descent isn't exactly right, Capt. Burke adds, he will abort the landing, because "the plane can just quit flying on you. There is simply no time to recover." Some pilots, reflecting the joking camaraderie of their ranks, have adopted macabre nicknames for the MD-11. "Death Star," some facetiously call it, according to the Air Line Pilots Association's safety-committee chairman. Others call it the Scud, after Iraq's unpredictable Gulf War missile. |
From the stand point of a casual observer;
Could the violent up-down movement seen on the video have been caused by freight breaking loose after initial heavy impact? in my mind, freight shoving backwards, then forwards, then all over the shop would be enough to cause all sorts of weight distribution/CofG problems? go easy - I'm still learning :8 |
Design Question
Can anyone please point to any documented design parameters for subsequent aircraft models (be it Brand A or Brand B) which have specifically taken into account the need to avoid the situation displayed by this accident? Namely those which take into account the previously-known handling characteristics of an MD-11 in particular (especially as a cited justification? - eg "touchy/sensitive" elevator control leading to new design feature as follows, ..., bearing in mind MD-11 behavour X/Y/Z)?
Put another way, are there any formally-documented design criteria post the 1970s/80s which point to a subsequent overall aircraft design feature which particularly avoids the "known" handling issues of an MD-11 (eg that which has apparently led to the accident in NRT)? I accept the -10 to -11 changes in design but seek information about other manufacturers takng certain things into account. Also, I'm not a "legal eagle", just curious about whether "known" handling difficulties in one type have been acknowledged/rectified in subsequent airframe designs by other manufacturers. |
Looking at this video (there are more than one),
BBC NEWS | World | Asia-Pacific | Fiery Tokyo plane crash kills two if you quickly stop/start the video between 4s and 5s in then the starboard wing seems to be swept back at a massive angle at one point |
Just because the MD11 is certified to a certain structural limit (Xg) doesn't mean the wing should fall off when that structural limit gets to
X.1g! *************** actually it can withstand abt 3x its certified limit. |
The above referenced BBC link states that this was the first fatal accident in the history of NRT which opened back in 1978. If true, then that is an impressive stat all by itself!
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This is very pertinent. Boeing designs its landing gear to shear off under excessive vertical loads; this is far safer than having it break the wing spar, as apparently happens on the MD-11. I think this goes back to when McDonnell took over Douglas; McDonnell had never designed anything except military planes, and if they met specifications then everyone was happy. Boeing, Douglas, and Lockheed, however, had learned that when designing airliners you made it as safe as you could, period. The regulations were regarded as just the starting point. I am convinced that many of the problems with the DC-10/MD-11 come from the fact that the military people at McDonnell were in control of the company, and the Douglas people who really knew how to build an airliner were not listened to.
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SEPilot,
That occurred to me many years ago after discussing handling probs and the small tailplane with an AA "Scud" driver. Douglas pretty much bankrupted itself into the hands of McDonnell by building tough airframes. When the St Louis outfit took over the financial reins, its first civil creation, the DC10, was pretty much a General Dynamics fuselage mated to a Douglas wing - primarily because DC9 demand was putting a strain on the Long Beach facilities and it was more cost effective to build the fuselage elsewhere. The over large tailplane of the DC10 was a cheaper alternative than an active de-icing system and the MD-11 contains hall marks of fighter thinking in its wing position, the redesign of the tailplane and many of the handling features. I've yet to meet anyone in engineering or who flies the MD-11 with anything really good to say about it. |
Can anyone post the decision logic of the LSAS system? I can discern some of it from the FCOM discription, but not all of it. Anytime automation is "in the loop" at the time of an accident, I think it's worth looking at.
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What is the max certified g limit - 2.5g? I can't see that landing being more than 7.5g. I agree with the previous poster's comments about g force varying throughout the structure.
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Just because the MD11 is certified to a certain structural limit (Xg) doesn't mean the wing should fall off when that structural limit gets to X.1g! *************** actually it can withstand abt 3x its certified limit. FAR25 says: "Sec. 25.303 Factor of safety. Unless otherwise specified, a factor of safety of 1.5 must be applied to the prescribed limit load which are considered external loads on the structure. When a loading condition is prescribed in terms of ultimate loads, a factor of safety need not be applied unless otherwise specified." Please have a look at the youtube video of the B777 wing load test. It breaks at 154% limit load, proving designers don't put in more strength (and weight) than necessary. |
I think Harrymann may be on to something.
First we have from the FCOM During take-off and landing flight phases, when (LSAS) PAP or PNL is active, approximately 10-15 pounds of force on the control column is required to override LSAS. 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. What am I missing here? |
Meaningless
“The above referenced BBC link states that this was the first fatal accident in the history of NRT which opened back in 1978. If true, then that is an impressive stat all by itself!”
If you’re an ‘American Football’ or ‘Baseball/Basketball’ fan, then yes I can see how you’re impressed by a meaningless statistic! |
What is the max certified g limit - 2.5g? I can't see that landing being more than 7.5g. I agree with the previous poster's comments about g force varying throughout the structure. The airworthiness requirements, FAR 25 for transport category airplanes, are all on the web. Here is a link and here's the basic requirement for the landing gear. "Sec. 25.473 Landing load conditions and assumptions. (a) For the landing conditions specified in Sec. 25.479 to Sec. 25.485 the airplane is assumed to contact the ground-- (1) In the attitudes defined in Sec. 25.479 and Sec. 25.481; (2) With a limit descent velocity of 10 fps at the design landing weight (the maximum weight for landing conditions at maximum descent velocity); and <....>" So the gear must withstand a 600 fpm descent rate as the service limit load, and in the certification tests it must pass one test at ultimate loads corresponding to 900 fpm. Note also that there are a number of conditions attached to those requirements, in reality it's not just that simple number. |
The certification requirements dictate what loads the landing gear must take, they do not dictate what happens when they are exceeded. This is where real design takes place; to make sure that when it fails it does so in the most benign fashion possible. In this case it would be that the landing gear shear off, but with the MD-11 it appears that it tends to break the wing spar. Note the BA 777 at Heathrow; had it been built like the MD-11 and the wing spar had broken instead of the landing gear going through the wing that one might well have ended up on its back as well, and in that case it is highly likely that there would have been fatalities. If the gear would have detached in the same manner perhaps none of the three MD-11's that flipped on landing would have done so.
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I have plenty of good to say about the MD11.
But it is not proper right now. Two of my coworkers are dead. We'll discuss it later. |
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