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MK Airlines B747 crash at Halifax

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MK Airlines B747 crash at Halifax

Old 2nd Dec 2004, 21:08
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On PickyPerkins latest photo above, the starboard outer landing gear lines up with damage at the rear of the berm, circled in red on the photo below.

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Old 2nd Dec 2004, 22:14
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quote:
Quite agree with that, unfortunately it's not the people who do the twisting that end up getting bitten.

I second that. Fatigue is almost always a factor in every aircraft accident in which pilot error is a cause.

I'm not saying pilot error was the cause in this one, but authorities really need to get together and come up with realistic flight/duty times. Given the international nature of air transportation, it should be something that every country must follow.

I love how MK mentions that they are changing this rostering practice on accounts of "safety studies" done before the accidents. I would really like to see them reproduce the documents proving their so called "studies".
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Old 2nd Dec 2004, 23:04
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Hobie, I wish I knew. Bureaucracy and budget conspire against what we might think of as practicality everywhere. But is it totally unreasonable to build, say, a berm, for the lights to be mounted on, 200m beyond the threshold? Even if the land beyond is flat and only woods? You and I don't know the extent of airport property; perhaps those woods belong to someone else. And in so many places, 200m would put you in the middle of the sea, or of a densely populated area built up gradually many years after the runway was originally set there.

You have to keep coming back to basics, i.e. that runway lengths are known facts and that, if you're going to operate aircraft in and out of them, those facts have to be acknowleged. For better or for worse, no company can run an airline on the basis of the minimum dimensions or of the forgiving qualities of the safety envelope. If that were the case, would anyone ever have landed at Kai Tak?

Just a thought based on a local airport's movement. I live a stone's throw away from the southern threshold of SDU, Santos Dumont, the downtown Rio airport. 30m from that threshold is a pile of boulders (at the other end there's a ramp leading down into the sea, originally intended for hovercraft) and, beyond that, the sea. Thirty metres, I said. There is absolutely no room for indecision. SDU's no different from so many airports around the world; they each have their own restrictions. Like Halifax.
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Old 3rd Dec 2004, 00:22
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In my fading memory of Davie's chapter on the 747:
  • The wing gear has considerable vertical travel. If only one wing gear comes down, you have to retract it as it will otherwise keep coming down and tip the a/c.

    I suspect the wing gear came up on its struts as it contacted the berm while the body gear had less travel. Add to that the flex in the wings as they generate [insufficient] lift. These factors cumulate in less loading on the wing gear.

    The removal of the structures on the top of the berm in the path of the wing gear show that it was down there. Note that the nacelles did not take out anything on top of the berm which further indicates that the wing was developing some lift.
  • The body gear can pivot in taxi turns -- this along with progressive deformation of structure may explain the divergence in the tracks.
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Old 3rd Dec 2004, 06:50
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If memory serve me right (last used my Ghanaian Licence 4 years ago) under GCAA rules with a heavy crew

Which was 2 complete crews, but due to the intervention of the now defunct Ghana Airways was amended to 3 Pilots and 2 FEs the max duty period was 18 hours

With a provision to extend to 20 hours due to unforeseen circumstances. The GCAA rules are loosely based on the FAA regs.
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Old 3rd Dec 2004, 22:18
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RbF,

Just looked at Hobie's posting of the side view of an MK 747 departing and from that it would seem the gear all retracts at once, not "outboard first, then inboard". And that the outboard gear aligns its "dangle" close to the well rather than prior to the folding-inward motion. So the thought I threw out earlier re an attempt at gear retraction is probably off base.

The only other thought that occurs is that the outboard gear is designed to compress more easily; it's the first to touch the ground on landing and the last to leave the runway. Could it be that the outboard gear actually did ride up the berm but, more easily compressed, without leaving marks discernible in that low-resolution photo?

If the outboard gear didn't touch the berm at all it's back to AoA.
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Old 4th Dec 2004, 18:08
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In a post on 1st December 2004 I asked three questions:

(a) how far behind the outer bogies are the inner bogies on a 747-244?
Answer is 10 feet 1 inch.
(b) how high is the berm?
Answer estimated to be 11 feet 6 inches (3.49 meters).
(c) and hence what must that minimum nose-up angle have been for the outer bogies to have cleared the berm?
Answer is that no angle allows this.

TyroPicard 2nd December 2004 18:37
Even if you point a 747 vertically upwards the wing gear is nowhere near 4 metres above the body gear. From the side, on the ground, each pair of bogies looks like this: OOOO no overlap but not much of a fore/aft gap.
You are absolutely right. The front gear is 3.07 meters from the rear gear. The spacing between the wheels on a bogie is about 12 inches, and between bogies as seen from the side is about 17 inches.

broadreach 2nd December 2004 21:46
Perhaps you're right, Picky. But, just perhaps, there's a little window of AOA where the outboard gear is dangling but still a foot or so above the inboard gear which itself, along with the tail, is only a foot or so off. ………..
I afraid that the numbers do not seem to indicate that an AOA window could be possible.

TyroPicard 2nd December 2004 21:43
Why not make the theory fit the evidence? The ruts were not made by a 747, but by something else. The berm is covered with traces of similar ruts!!!!!

broad reach December 2004 12:49
……. I am going to stick my neck out a bit further and make a guess as to what happens when the centre gear of a fully loaded 747 suddenly encounters a steep gradient which I'm estimating at 4-5m high and very solid. The gear assembly fully compresses and then punches up into the aircraft up just aft of centre, breaking its back. ……

broadreach 3rd December 2004 18:18
.......... The only other thought that occurs is that the outboard gear is designed to compress more easily; it's the first to touch the ground on landing and the last to leave the runway. Could it be that the outboard gear actually did ride up the berm but, more easily compressed, without leaving marks discernible in that low-resolution photo? ........
Maybe the change in the theory should be that either the outer bogies ran up the slope without leaving a detectable track or that they punched up through the wing but the rear ones did not collapse (the grass between the tracks seems to be undisturbed). The outer legs are twice as long as the inner ones, and supported by the wing structure which may be less robust than the fuselage structure.

I estimate that the front wheel of the front bogies at their dangle angle would at near the level of the top of the berm if the rear bogies and the tail were in contact with the ground.

I see shadows of the antenna masts on the berm, but no similar ruts.

The answers given at the start of this post came via page 188 of a pdf document on the www.boeing.com site, “747 Airplane Characteristics, Airport Planning”, May 1984.

Page 188 shows a drawing with a front/rear bogie spacing for 747-200 aircraft of 10 feet 1 inch.

From the same diagram the spacing between the outer wheels of the rear bogies calculates to be 16 feet 3 inches.

The photo of the tracks on the berm show this distance (always assuming that these tracks were made by these bogies) is about equal to the slope height of the berm, i.e. the outer tracks and the top and bottom edges of the berm form a square. If the slope angle is 45 degrees, then the vertical height of the berm is 11 feet 6 inches.

By the way, the wheel spacings which I earlier estimated from photos and posted on Dec. 1st as being in the ratio of 1:3.3:3.5:3.3 are actually (from the Boeing document) 44:141:151:141 inches, a ratio of 1:3.20:3.43:3.20. Near enough.

Cheers,

Last edited by PickyPerkins; 4th Dec 2004 at 23:03.
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Old 4th Dec 2004, 22:49
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Gosh, we all seem to be basing so much on a single photograph! And on the unlikelihood of just two centre gear marks apparent on the berm.

What seems most unlikely to me is that the four tracks up the berm shown in the photograph taken shortly after the accident could possibly have been made by anything else that the MK aircraft. Yes, I'll wait for the report but I'll be very surprised if the tracks happen to be from a passing tractor! And I am, of course, intrigued at the lack of outboard gear tracks although there may be just a hint of the starboard gear's passage at the very base of the berm.

It the faint mark of the starboard gear is, in fact, that, where are those of the port gear? Could it be that the outboard gear bogies rode up the berm without leaving marks or, by reason of the greater length of the strut, collapsed and folded back a fraction of a second earlier? The inboard gear certainly wouldn't have had the option of collapse; it would go up the berm or through it.

Another thought. The berm is covered in grass. But the ground underneath is pretty hard at this time of year. If, in fact, the tracks leading up the berm are this aircraft's, just to get that deep might indicate a very heavy impact.
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Old 9th Dec 2004, 20:51
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If your recollection is correct, Engineer that would put them a good couple of hours outside even the extended max permitted duty period, having taken off from Luxembourg to cross the Atlantic twice.

as an aside why sre folks so strung up on the precise point at which each part of the aircraft hit the ground? Even if the berm hadnt been there the aircraft would certainly have hit the trees a bit further on.
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Old 9th Dec 2004, 21:00
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ShotOne,
__________________________________________________
Even if the berm hadnt been there the aircraft would certainly have hit the trees a bit further on.
____________________________________________________

How can you be so sure of that?
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Old 9th Dec 2004, 21:36
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ShotOne
.... as an aside why are folks so strung up on the precise point at which each part of the aircraft hit the ground? Even if the berm hadn’t been there the aircraft would certainly have hit the trees a bit further on.
While you are almost certainly right, we do not really know that the berm made no difference, do we? The plane was almost flying when it reached the berm.

One the other hand, the accident was well under way before the plane reached the berm so that in that sense the exact events at the berm may not be relevant to the primary causes of the accident.

However, to my mind it is interesting to look at what must have happened. Please skip the following if you have no interest in the details.

The Boeing pdf document “747 Airplane Characteristics, Airport Planning”, May 1984, has a scaled drawing of a 747 which when overlaid on the photo of the berm allows one to see which parts of the plane passed over which parts of the berm. I hesitate to show the drawing here (copyright considerations), but the following diagram shows the results of such a comparison.



Note: In making this diagram:

(a) the plane’s dimensions have been scaled so that the inner wheel tracks in red lie in the four ruts at the BASE of the berm.

(b) the photo has been rotated so that the center line of the fuselage lies along the broad whitish track beyond the berm. I assume that this track was made by the aircraft sliding along the ground either going or drifting slightly to the right of 90 degrees to the berm.

Observations:

(a) when orientated as detailed above, two of the red wheel tracks lie on the right-hand pair of ruts in the photo all the way up the slope of the berm, while in contrast the left-hand ruts diverge away slightly to the left, as though the left-hand undercarriage was beginning to collapse.

(b) the eight wheel tracks in red correspond approximately to the positions of knocked over antenna masts (as has been said before).

(c ) the remaining undamaged antenna masts show that, although the rear fuselage is known to have hit the berm, the wings (purple), engines (green) and tailplane (blue) must all have cleared the tops of these masts.

A little gentler slope to the berm and there might have been a “ski jump” take off.

Cheers,
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Old 9th Dec 2004, 22:00
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This is my first post (nice to be here). I live in Halifax and work at the airport in a regulatory capacity.

As to the thought that a "non-ski-jump" berm might have been a contributing factor in the tragic accident, is it not correct that the lowest part of the aircraft should have been a minimum of 35 feet above any obstacle at the end of the takeoff run (including clearway, as appropriate)? Canadian runways have very strict design criteria. I really do not think that the location, nor angle of the base of the berm, should be considered as a pertinent factor.

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Old 9th Dec 2004, 22:43
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Three thoughts:

1) PP, thanks, you've obviously gone to a lot of trouble on those diagrams and it will no doubt be interesting to compare them with the final accident report. Just one thing we might all take into consideration is that it's extremely difficult to judge, from our distance, all the possible factors that contributed to the accident. It seems to be a given that the aircraft hit the berm and that, at this point, the tail separated. In such a violent collision our theories based on the scant evidence available to us are but chaff.

2) ShotOne, no intention here of getting into the overworking/exhaustion discussion. But stating categorically that the aircraft wouln't have made it past the trees some 300m distant is, er, too categorical. They might have, even with some evergreen boughs in the undercarriage. Or it might have developed into something less lethal, like the Mulhouse A320 accident from which most walked away.

3) SimBoy, tend to agree with you, "should have been" being the operative phrase. We all, sorry most of us, live and learn that what should have been could be a little bit better, had we thought of it earlier. Not suggesting here that Halifax should demolish the berm but yes, perhaps, the airport authority might give some consideration to whether the lighting support could be made a bit less menacing.
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Old 9th Dec 2004, 23:17
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The berm hosted the localizer antenae for runway 24.

SimBoy

Last edited by SimBoy; 10th Dec 2004 at 20:11.
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Old 10th Dec 2004, 08:34
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Bumps and berms

I say it again..willy-nilly of all the theoretical talk of 35feet screen heights etc,if it is atall possible,the ends of runways should be clear and flat..maybe covered in gravel or brush of a certain thickness and height.It is the sudden stop that kills.
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Old 10th Dec 2004, 14:20
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Just to set the record straight, simboy is correct - those "red thingies" are not lights, they are the elements of the ILS localizer array.

That ILS was one of the early CAT II installations in Canada and, if memory serves correctly, the berm was built when the ILS was upgraded to CAT II standards.

Maybe the antennae had to be elevated to produce a signal that meets CAT II tolerances, perhaps due to runway slope. In any event I do not recall any indications on airport or runway-specific performance charts that indicated a clearway problem.
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Old 11th Dec 2004, 23:45
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broadreach perhaps I should have used the word "probably" rather than "certainly" as regards hitting the trees. Either way, as someone pointed out, the accident was well under way by then -and at other airports MK use it would have been buildings and cars

and why don,t you feel the fatigue aspect is worth discussing? surely it could be very relevant in letting us find what went so horrendously wrong in the flight deck that night
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Old 12th Dec 2004, 01:03
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the ends of runways should be clear and flat.
Should? yes.... Possible everywhere?

.....not at all!!!
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Old 12th Dec 2004, 11:45
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ShotOne,

Agree with you as to "probably". They would have had a marginally better chance.

The fatigue question bothers me because there's a general tendency on here to prejudge, to assume that the crew were fatigued and that that was the main contributing factor. From there to blaming MK for inhuman rostering etc is soo easy.

It may well turn out that this was the case. But the investigation will first be trying to establish what the physical sequence of events was, then whether the sequence was incorrect and, finally, why it was incorrect. And that's when you start considering the fatigue issue.
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Old 13th Dec 2004, 02:19
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Well doesn't everything on this entire thread come under the heading of pre-judgement? The official report will not be out for some considerable time -indeed I don`t think the report for MK's last crash is even out yet.

We DO know the duty period was very long and would have involved two Atlantic crossings. We do know that this would have been illegal if the aircraft was UK as opposed to Ghana registered and we do know the crew are likely to have been very tired. These are hard facts not speculation like much of what we`ve read here.

Of course we don't yet know the full train of events but I absolutely disagree that the fatigue aspect should be off limits just because we don`t yet know the cause for sure.
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