A discussion about fuel load is a sidebar perhaps of technical interest. Even given what is known at this point, I doubt that it figures in terms of cause.

FWIW- The initial 767 cockpit was designed for 3 crew- but with the then onset of two crew- additional rerouting of several systems ( eg hydraulics and switches rerouting ) About that time the chicken cannon was brought into play ( firing a frozen chicken from an air cannon into a partial cockpit structure to determine windscreen and ' skull cap ' strengths). Forget the weight and speeds involved ..
The result was that the ' skull cap' above the windscreen and the window framework had to be redesigned mostly with titanium. The skull cap cuz some important switches and valves were located there and damage or loss could cause major flight control issues- but still had to be within reach of pilot and copilot..

While the first one or two flyable 767.s built may not have had the rework, I am sure all the rest had that redesign.

Birds have penetrated the forward bulkhead in front of the cockpit of a 767-300 at least once before. Medium sized birds blasted through it on one flight, fortunately missing the Captain but sending blood, guts and feathers against the aft left wall of the cockpit.

I thought it was only the Air Force that supposedly forgot to defrost the birds before the test ... ?

tdracer said ..One subtle reason for the very long fatigue life of the 767 and related was the extensive use of two Boeing devlopd processes. One being a technique called ' coldworking " details of which can be found in manuals, info provided by Fatigue Technology ( http://www.fatiguetech.com/ ) developed in the late 60's by Lou Champoux ( next to my desk ) at the time.. In simple terms, bypushing/pulling a mandrel thru a sleeve inserted in the hole - or a special mandrel without a sleeve, the hole stretches leaving the nearby surrounding material in tension, which then results in major fatigue improvement. This techniques was used on main spars, lower wing panels, parts of wing box and some parts of fuselage, etc.

The second process also ' first ' used on major spar assembly was/is called ElectroMagneticRiveting - which uses magnetic drivers to drive and expand a rivet in ONE blow, which also has a major effect on fatigue life. Although the process had been used on smaller parts/assemblies since early 747 days, the use on major spar assembly was a first on 767. The machine was known as ASAT automatic assembly tool. That also was the founding of a company used around the world as improved and further developed by a company called Electro Impact - whos major facility is next to Boeing Everett. They have branched out since then with major wing composite layup for 777X. And no - I do not and have not worked for ElectroImpact or Fatigue Technolocy but have had many personal contacts/background with those involved in both companies over the years.

details- details- A careful check will reveal the particulars- as to just how much frozen the birds, turkeys, etc were at time of launch/firing- I did not fbeleive it was necessary to define/explain the exact test parameters. And birds have been found to impact jets at altitudes well over 15,000 feet.
My point was to SIMPLY explain the test used to detrmine design parameters, I'm sure the FAA an various wildlife protection agencies can explain why chickens and turkeys instead o geese, etc.


see also

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Part 121 fuel requirements
 

I'm pretty sure the fuel thing is a red herring; but under 14CFR Part 121 there is no requirement to land with a specific amount of fuel.
The aircraft must be dispatched with a planned amount of fuel on landing. If you burn it all without declaring a problem to ATC and your dispatcher that's a violation; but it's a planning requirement only.

Its Atlas. As well as the Amazon 767 s they operate the worlds largest 747 fleet. 400s & -8's. They know what they're doing.

The Mythbusters admitted their early 'chicken gun' tests on a Cherokee were akin to testing cardboard with a .357 magnum ....

Instead of all these what-if combinations I would prefer to parse the discussions down to the supporting facts at this time with no more than one leap of speculation beyond what is known.

Question. Do we know the length and spread of the debris trail ?

does that give us a hint of the attitude of the plane during break-up?

I heard it....very faint.

Remember the B-737 rudder hard-over issues?

Does anyone here know of any similar issues/instances on the B-767?

Tim Vasquez, meteorologist in Texas here... weather data analysis is what I do for a living, and some of you may remember me from the Air France 447 study about 10 years ago.

Regarding the 767 crash in Houston, a lot of images seem to be floating around that use default radar mosaics. These are problematic as they're focused on higher intensity levels, they are not very granular, they often carry an ambiguous scan time, and they're often built from composite products which are the result of multiple scans rather than a single scan. This makes it very difficult to use such data except to define the basic environment. In fact, I initially didn't think much of weather being a factor based on the preliminary images I saw. However I went ahead and accessed the raw WSR-88D base data files, which are for a single level and accurate to within about 1 minute, and I found some interesting stuff.

First of all, one caveat with these images: the ones I've posted here are built from 0.5-deg scans, which were underneath the 767 at a beam center altitude of about 2000-2500 ft and a beam width of about 2000 ft. I used these because there are usually a lack of scatterers at the higher tilts, and most of the convective circulations we see above 5000+ ft are initially generated near the surface. So there are indeed some assumptions about what is going on up at 5000 ft, where the problem presumably started. Time stamps are based on the FlightAware track log, which comes straight from the ASDI feed. My assumption is these times are accurate. Sorry for the watermarks, I got burned back in 2009 by the media reprinting my diagrams commercially without permission.

A couple of conclusions:

* A textbook gust front is clearly shown within 3 nm of the crash site. This correlation is definite and is striking.

* There were no thunderstorms within 5 nm of the crash site. There may have virga or weak showers though.

* It appears some sort of gust surge developed over northern Trinity Bay, lasting about 10 minutes, originating from the storms further west near Baytown, and it reinforced the gust front. This developed ground-relative motion of 50-60 kt along a band 6 nm long oriented NE-SW.

* Velocity product showed a transitory divergent couplet with 65 kt of shear within a 1 nm volume, slightly below and left of the track. This could be a piece of the northern edge of the gust surge. This is probably associated with turbulent motion, as the result of shear & friction along the frontal boundary.

* Velocity at higher levels (4000+ ft) and along the forward edge of the gust front are typically difficult to determine in these situations because a lack of scatterers.

* I don't think a gust front like this is anything that looks particularly dangerous. That said, it's impossible to directly measure turbulence, and in between the turbulence and cloud scales there are often strong circulations that can go undetected. Typically when we see small-scale patterns on radar imagery with strong gradients and circulation, we consider the possibility that strong motions can extrapolate down to the smaller scales. It's certainly possible that this gust surge rolled up into a vortex like I've shown in the cross-section below.. this can certainly be a hazardous area to fly in.

In short I'm skeptical weather caused a direct effect, but I do see enormous potential for a sudden, rough ride here, and that could have been the first event in a chain that led to something like a CG shift or loss of a control surface (from fatigue, improper maintenance, design issue, something like the 737 in Colorado Springs, etc).

It would be interesting to see what the TDWR radars showed, unfortunately as I have to attend to my other work I probably won't have time to look at this.

Anyway this is just an armchair analysis and I'm sure the investigators have more information at this point than we do, but it's nice to have quantitative data to work from.

https://cimg2.ibsrv.net/gimg/pprune....ed46ca4f92.jpg

https://cimg6.ibsrv.net/gimg/pprune....8eaf05a485.jpg

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https://cimg5.ibsrv.net/gimg/pprune....b0d22176aa.jpg

https://cimg4.ibsrv.net/gimg/pprune....701b58a3c1.jpg
Conceptual vertical cross section of air flow along a gust front ahead of a microburst.

NTSB presser just finished. There wasn't much new that hasn't already been covered here. One item of mention is that there is a video of the plane going down which was taken from a camera at the Chambers County Jail, a bit more than a mile away.It shows the plane in a nose down attitude for about five seconds. The video has been sent to the NTSB labs. It won't be released to the public until it's made part of the official NTSB docket, probably some months from now. The Chambers County Sheriff did say two bodies have been recovered; they have not yet been identified.

Great post tim, and great data collection nice to see posts with unbiased/ non speculative content

Prayers to the crew and the families.

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Excellent stuff Tim! It looks like a situation to me where it is extraordinary if the gust front didn't have something to do with it, given its proximity to where the accident occured but also extraordinary if i did because of how it seems like just a routine front. As you say its possible it set of a chain of events. This is just pure speculation on my behalf but any airline pilots will know (I'm only an instructor) but is it possible some kind of gust/turbulent/wind shear event could lead to the autopilot disconnecting and thus being miss managed, like forgetting that the auto throttle has also disconnected?

Exactly! Too many flight sim/armchair warriors here as usual

Re: the NTSB photos above.

Does anyone think there is any significance to what ever it is they are measuring and documenting (punctures and imbedded material?)?

How about waiting for some facts to surface?

I thought the reported size of the debris field was pretty significant

the debris field is possibly large because it apparently dove straight in from around 6000'...and hit the bottom....

Those pieces do not look to me like parts of the engine nacelle - the honeycomb is too thick. Best guess is a moveable aerodynamic surface (e.g. flaps or part of the tail)

For those unfamiliar with Texas geology, I'll provide a brief description of the soil in and around Trinity Bay, hoping it makes understanding the conditions which exist at the impact site easier to visualize.

Basically it's a very deep layer of dark, stiff clay, with little else except some loam around creek beds and occasional fractured blue clay. There is very little sand on the coastal beaches of the bay area, and the impact area consists of marsh grasses and the dark clay already described, with the surrounding water levels between one and three meters.

Recovery of recording devices and airframe debris may be extremely difficult, especially if specific parts suspected of failure are to be located. I was a bit surprised that the bodies of two crew members have already been recovered, I hope this provides a degree of comfort to loved ones.

I wouldn't consider 100m x 200m large at all - in fact for an aircraft the size of a 767 that's on the small side. It would also rule out any in-flight breakup (unless of course they find bits at another location).
I also would consider an uncontained engine failure to be rather unlikely since they'd have been at a relatively low engine power setting - most engine breakups at takeoff power sets, or at high altitudes where the physical rotor speeds tend to high. I suppose a major bird strike might cause enough damage and a large enough imbalance that perhaps the engine could start coming apart, but again the probability would be low at relatively low rotor speeds.
But, one of more big birds through the forward bulkhead that took out some flight controls (remember, the 767 is basically a cable controlled aircraft)? Even if it didn't incapacitate the crew they'd have precious little time to react...