http://i337.photobucket.com/albums/n...vidcap003b.jpg

Hmm would a colour camera/lighting system be of any use in that depth/darkness? Talk about the proverbial needle in the haystack.

Slats11, your comment about education and FBW resonates with me when I translate it to terms with which I am intimately familiar.

I to some degree liken FBW to a new radio coming out that links several controls into three or four push button settings. Unless you know what those settings really amount to in terms of the old controls and understand the old controls you cannot wring the maximum out of the radio. Radio manufacturers stepped back a little and more or less gave access to the old controls within the context of the buttons. Newer high end radios have wider selections of filters. And the filters can be tuned, which can substitute for the tricks you used to do with the old controls. But, if you never learned the old controls it still seems to be difficult to extract the best out of the radios.

Looking at FBW in aircraft, unless the pilot knows how to fly the plane to the edges of its envelop without computer interference and unless the pilot knows precisely what steps the computer took before it "gives up" and hands control back to the pilot, it may be hard to recover as the pilot goes back over ground the AP already covered.

I don't know if this is a clear explanation. The extractable information is that I've found computer aiding is helpful; but, you must know intimately what it is doing and has done if you need to wring that last critical bit of (life saving?) performance out of the machinery.

Is there this level of knowledge among the flight crews today?

Graybeard and ChristianJ - thanks for reminding me of the slot antenna. In '68 they were still under development as dielectric loaded slots by one of my professors at Univ of Mich. I'd had the impression they were basically designed for VHF at the time.

You got me looking. It's apparently a vertical slot on the lower portion of the VS structure. That would be slightly lower efficiency. But, it doesn't much matter. Communications to DAKAR are possible. And at 6.6 MHz even that antenna would be noisier than any (sane) radio connected to it. This reception is not antenna limited. The pattern might be a problem. I'd expect that always to be a problem rather than specific to AF447's situation. (Does anybody know of a good picture of the antenna unmounted from the aircraft? I'm curious precisely how it is constructed. It's not what I grew up calling a slot antenna. But, with the one picture I have of it, there's not a much better short name for it.)

And finally it bears no importance to the AF447 situation because DAKAR did not have the plane in its list of planes to listen for and Brazil never tried using SelCal when calling the plane. The lack of communications was procedural rather than somehow related to an antenna that doesn't work well.

ChristianJ, those gray patches don't look like the diagrams I have managed to find.

Re: Yes: Airbus submits patent for airspeed error monitoring

Fascinating - for those only worrying about US patents, there is ample prior art in discussion here on PPRUNE to get the patent tossed out.

I first came across slot antennas in my early 'radar' days, and that was SHF, and far earlier than '68.

I'd be interested too, both in seeing your picture, and any others that somebody might have.

They were more green than gray... I doubt that the slots were 'dielectric loaded'. I think you're just looking at the honeycomb fibreglass covers of the two "sawcut" cavities.

This all being slightly irrelevant to AF447, maybe us 'radio geeks' should open a separate Tech Log thread about HF aerials on airliners?

Sure, here it is: LF vs AoA

PS: Same data in different format were posted 31st jan 2011, Post #2663 on the previous thread: A330_gustloads

It's not so much the depth and darkness as the basic properties of water. Water absorbs (or scatters, or both) light at the red end of the visible spectrum, and to a lesser extent at the blue end. This leaves a transmission peak for green light, with the overall effect that color pictures, of sunlit scenes, taken at depths of more than a few meters have a strong blue-green tone. (I suppose modern CCD cameras may be able to color correct that to some extent.) This effect is modified by the presence of other things in the water, such as algae and plankton at temperate and polar latitudes. In the tropics, ocean water, viewed from above, looks very blue due to scattering, I think, and is often nearly free of marine organisms. Deep sea water is usually very clear, also.

Electromagnetic absorption by water - Wikipedia, the free encyclopedia

So, in answer to the question, deep sea photos require artificial light, as all sun light has been absorbed. That light is often white, as is the xenon strobe on the REMUS 6000 vehicle, or it could be green (thallium-iodide arc lamp, green LEDs, etc.) to take advantage of the transmission peak and scattering minimum. When photos are taken at close range (both the light and camera close to the subject), as is generally the case for ROV and manned submersible work, color cameras are normally used and the colors look natural, or close to it. When the range is greater, the light that travels from the source to the subject and back to the camera becomes so dominated by blue-green that a color camera adds very little. Furthermore, a B&W camera is usually more sensitive (works with lower light) than a color camera using similar technology, so operation from greater range is enhanced. Modern CCDs have become very sensitive, but in the earlier days of underwater video imaging, intensified cameras were sometimes used, and the intensifier was applied to a monochrome camera.

REMUS would fly at 5-20m (typically 10m) above the bottom for photo work, depending on water clarity and height of possible obstructions. The two-way path length is thus quite long and there is little usable color. If any ROV images or video are released, they are likely to be in color.

The ultimate range of underwater imaging is usually limited by back-scatter from the water and the particles in it, which fogs the image. That is a large topic, not related to the question, but I thought I should mention it.

As a side note, I expect that the visible spectrum (spectrum of light visible to humans) is so narrow, being less than one octave from about 400-700nm, exactly because of the absorption properties of water. Either because our retinas are sensitive to the light that gets through our water-filled eyes, or possibly because the type of eyes we have evolved in water dwelling lifeforms. There is probably known science on this, I'm just not familiar with it.

I suppose I opened a bit of a hornets' nest with my comments regarding RF communications by AF447.

I'm a radio amateur and not a radio professional so my observations are based on empiricism but I believe that electromagnetic propagation is still a poorly understood science (not only by me) and at times will not conform to engineering specifications.

My object was to point out the perversity of inanimate objects such as non-vacuum electromagnetic propagation media (and in previous comments - computer software) as observed by Major Edward Murphy and published by his colleague Col. John Strapp M.D. who understood the medical maxim: never say that something never happens or that something always happens. This applies to all professional endeavours.



AF447 foundered is spite of the collective wisdom of all who created and operated her.

Design constraints for airliners HF antennas
 

"maybe us 'radio geeks' should open a separate Tech Log thread about HF aerials on airliners?"

Considering:

1) Crescent EMI/EMC challenges (High RF pwr near sensitive front end circuitry).
2) A clear room for performance improvement
3) A probable "extra life" for HF
4) The passion for the issue :ok:

Why not to open it asap?

I would modify your maxim to wit. 447 was lost perhaps because the collective was not complete, or some of it was insufficient or incompetent.

This was not an act of GOD. This was a failure(s) that killed people. If we knew it to be a fluke, and nothing was to be found as to cause, there would be no Phase 4, or 5. IMO.

HF aerials
 

Hi, KMD OM

Here is Charlie Whiskey, (not OM like you, just 60), hihi

Let´s develop a thread on the issue?

Filtering issue
 

Some years ago i faced a challenging noise filtering issue so difficult i finally drastically changed the original design.

HF pick up by yaw damper in a supersonic a/c remembers me the space " butterfly region" of stones in spacecrafts flight path.

Very dangerous issue and a real threat to dense circuitry.

Bearfoil;

That is my point. I believe everyone put their best effort into designing and operating that A330 but conditions unanticipated by software writers, a dielectric black hole that swallows RF or shortcuts to improve the bottom line will eventually bite our buttocks.

It's all a teaching and learning experience we should not ignore.

Cheers

Comparing HF wire aerials vs newer designs
 

GB

Could you comment something on Signal strenght (pwr out) with new ones comparing to the old wire antennas? (not trailing wire)

Sounds good
 

"The proposed airspeed monitoring system would compare changes in measured airspeed over a short period of time with changes in ground speed as computed by the accelerometers and gyros in the aircraft's air data and inertial reference unit (ADIRU)."

If goes fast to "public domain" will be fine

A388
 

Links to see the design?

An English transcript of the video published on April 26 is now available at the BEA site:

Start of phase 5 of the sea search operations, English transcript

Re: Picture in post #162
 

Is this one of the underfloor support members?

If so, it gives an idea of scale.

ImageShack® - Online Photo and Video Hosting

From the published US patent application

The incorporated French patent submitted Sep 23, 2009

HN39.
Thanks for the LF/AoA graph. Thought you would rise to the small challenge!

Fascinating discussion on HF antennae and propagation, chaps... Yes, Graybeard, think the VC10 also achieved whole-airframe antenna from its fin-mounted thingy. Whereas the B707 just had the antenna sticking forward from top of fin. Aft reception could be difficult in my experience on some aeroplanes, but can't remember which ones of VC10, B707, A310, or DC10. Pretty sure the VC10 is better than B707 in that respect. Aerial-tuners also used to be a problem sometimes, leaving you with the inability to transmit. Changing freq sometimes solved the problem.

Re VHF-AM in static, I'd just like to point out that ear-splitting static often accompanies St Elmo's fire.
　
Re Airbus's proposal of using GS as a way of checking the veracity of sudden indicated-airspeed changes, the Flightglobal report quotes Airbus as saying:
"While airspeed and ground speed can not be compared directly, Airbus notes that over a "very short period", normally significant factors like windspeed, changes in altitude, air temperature and angle of attack will be negligible, allowing for a direct comparison of changes in speed rather than speed itself."

I wonder what "very short period" they have in mind. By definition, large aircraft never experience rapid changes in GS. IAS/CAS, on the other hand, changes very rapidly in gusts. In the different situation of entering a jetstream from the side, the tailwind-component (for example) can increase by 100 kts in two or three minutes. This leads to a steady loss of IAS, which has to be recovered by climb thrust to build kinetic energy until the GS has been increased by the 100 kts.

On walk-rounds, I sometimes pondered on the positioning of the three probes. #1 & #2 are usually symmetrically positioned; #3 usually near #1. All seem equally susceptible to icing. But is it only the shape of the probe itself that matters?

Another point: can't someone invent an even more powerful heater that could kick-in as soon as a sensor/camera shows the beginning of ice formation? On the VC10, we had an ice-probe visible under the captain's DV window. It had a light which enabled the captain to inspect it with mark-1 eyeball, and a heater to de-ice it. (If it was icing up, we would put the airframe anti-ice on.)

Wouldn't it be nice if pilots could actually SEE their pitot tubes?

Chris Scott,

I will analyze the HF antenna design of VC10, initial DC10 and the poor ones like in 767.

Will be a pleasure to do that.

Aft reception: When your antenna is at a/c tail you have a "ground plane to the front of it" making RX and TX much better than to the back of the a/c.

Just to brief you on the theory: if you drag a wire, bonded to fuselage, the aft sigs would be the same to the front. Better if the wire is quarter wavelenght of the operating QRG. In this case the antenna would be in the middle, symetrical (fuselage to the front and trailing wire to the back).

On St Elmo and static poor RX this could only be solved increasing the power out of ground station but unfortunately the days of the 12ACX and 4WTFA are gone. They are using lower power and this is an error. I will investigate the current power levels and antennas being used in DKR, REC and others.

I designed and used several antenna tuners and at certain QRG they simply don´t tune. (for a given antenna type). And frequently sparks due VERY HIGH voltage.

On trailing antennae see the one of E6 Tacamo:

Boeing: E-6 Tacamo - History

Trailing a wire roughly the same lenght of cruise FL, 30,000 ft.

The antenna is a dipole (end feed, similar to the one used in Zeppelin) and the radiating element is another wire, a short one. (~5,000 ft), feeded with a coil in the a/c antenna tuner.

The purpose for this is to put a signal to be received by a submarine. (E6 orbiting) in this case the dipole (horizontal) radiates to sea, sides an top of the a/c. For a ONE WAY comm to the sub. (Sub just in RX mode)

QRG around 17 KHz (under 20 KHz).

:)

Hi,

From not far from here (Internet is a small world :) )

Google Vertaling

Original:
« Deep trouble » pour le BEA

BJ-ENG

I think you are correct. Of the two decks, I think you are looking at the cargo floor (member). The Cargo floor, though shorter in span than the pax deck, also has 'bridging' to support the floor, while the pax deck is clear span. The piece of bridgework that remains attached to the floor member is relieved as the pic shows it would be. Also, there appears to be a remnant of fuselage frame remaining, so this piece would be located at the area where the cargo floor and fuselage mated. ??

Captain Scott

Last look I had at the 300 family, (A300) last August, there was a fourth pitot probe on the port side, is this a new addition? Is the A330 newly configured this way??

jcjeant

The Airbus cannot Stall, and it cannot come apart at altitude, So the BEA has reported as these truths imply: "Enligne de Vol" There is no need for looking directly under LKP, or within 40 nm for that matter. :uhoh:

HF slot antenna for the C130
 

JD-EE

At page 7 in the link below there is a good text on the issue.

Slot antenna

Thanks for the link jcjeant.

En ligne de vol ...

http://i25.servimg.com/u/f25/11/75/17/84/af447_10.png

For sure there has been AMS, but also Perpignan, and maybe AF447 ... ?
I find it peculiar Airbus is using a 737 profile to demonstrate the brand new procedure to survive a stall ...

DFDR found w/o memory module
 

Sans les Memoires??
 

No matter. What I want is to hear these two (or Three) pilots as they try to keep this heap in the air, after it has done its ignorant best to dive into the sea.

It will reclaim for them their heroism, and the shocking lack of dependability of this a/c on that date.

The wreckage is the key, and soon the lightbulbs will pop, as folks "piece" together how this happened.

Boxes optional.

There are two salient issues to remember, and these have not been addressed.

"There was NO evidence of forward momentum" (Horizontal, but 'backward'?)

What is MISSING from this "debris field"?? (Second engine? Wing parts?)

"Le chassis" (in the French text) may refer to the 'mounting rack', not to the FDR unit itself.
It's what I was afraid of... the recorder(s) being ripped from their mounting racks (not necessarily designed to the same crash-resistant standards as the recorders themselves), and making their own way to the sea bottom, and getting buried in the silt....
Good luck, guys...

Edit: Ignore, please. I've now seen the photos, and that's obviously the recorder unit, not the 'mounting rack'. Not sure whether the photos show the CVR or the FDR, though.

"Deep Trouble" for the BEA?
 

Quote from the piece referred to above by jcjeant (English translation of the original French):
"... BEA has never considered the possibility of "stalling".
…BEA has never contemplated that the A 330 could have come out of its flight. The BEA, however, only determined the search area according to the inverse hypothesis that "in view of the maximum possible speed of the aircraft, the wreckage of the plane had to be in a circle of 75 km radius (the circle) centered on the last reporting point position (LKP) "(Mr. TROADEC note of 8 April 2011).
"Deep trouble" for the BEA.

Only fair, I think, to point out the source of these accusations. It's a website called "Les Dossiers Noir du transport aérien" (Air Transport's Black Files), a "Blog citoyen d'un ancien commandant de bord" (Citizen's blog by a former airline captain).

One or two names spring to mind... As far as I'm aware, the accusations made are nonsense.

How can the writer say that the BEA has never contemplated stalling or departure from flight envelope ("sortir de son domaine de vol") ?

How can it be wrong for the BEA to define a circle of radius 75 km (40 nm) from the LKP as the search area? To my knowledge the BEA has never stated that the accident could not have taken place at or close to the LKP. (We still don't know where it happened, but that's another matter.) If they had defined and searched smaller circle, and the debris had turned out to be outside it, would that have led to another version of this conspiracy theory?

With the benefit of hindsight, the apparent failure to search closer to the LKP in Phase 3 looks unfortunate, but the difficult search seems to have been prioritised in the areas of highest probability. Eventually, the two search vessels (Anne Candies and Seabed Worker) simply ran out of time last year.

To accuse the BEA or any other organisation of deliberately ignoring the most likely site of the debris is preposterous. In any case, they would have known that the industry would never let them get away with it long-term. However frustrated the interested parties are with the delay in finding the main debris field, and however much we would all like to have unrestricted access to its progress, it seems to this amateur observer that the BEA is supplying a similar amount of information to that which has been disseminated in other investigations of comparable complexity.

Don't be silly, JAM. To draw such a diagram, you borrow from a generic database of shapes.
And not all aeronautical engineers are fervent 'spotters', you know?
To me, all them Coke cans with two engines look the same. Personally I can only just distinguish between the big 'uns and the small 'uns, and usually the only way I can pick out a 737 from the crowd of little 'uns is from the squashed nacelles.

BEA Information - APR 27
http://i25.servimg.com/u/f25/11/75/17/84/chassi10.jpg


http://i25.servimg.com/u/f25/11/75/17/84/chassi11.jpg

Hi,

I can agree on some of your points
Anyways ... do you read once "stalling" in the two preliminary BEA reports ...
I read this word many times here in Pprune .. not in BEA prose ...

Captain

I think you are missing something, and in doing so, appear to be sliding into what you yourself have bemoaned. This is not adversarial to the extent of being fatal to any argument. There are POV's as well as ROV's.

BEA is a closely connected agency with the principal interests in French Aviation. If you wish to promote the view that all is objective, independent, and scholarly to the exclusion of bias, we should talk.

If however you take the view that there is a history of adversarial and parochialism re: these issues, no harm, no foul.

It is legend that aircraft carry with them certain reputations. Are "Experts" hobbled with some of these prejudices?? Of course. LKP was the beginning of the problem, and the airbus cannot fall straight down, nor can it lose bits, so "we" plan accordingly, and perhaps reject preliminarily some critical data.

It's a plane, of course it can stall, saying it can't is like saying a t-tail with a stick-pusher "cannot stall". Both cases just have a bit more protection from stall - break or disable those and stalls happen (proven in past incidents)

As for coming apart at altitude, also already proven to happen (just need enough range on a SAM)

En Ligne de vol does not mean flying. The report with that phrase in clearly also shows it was falling like a brick, with low forward speed, but it happened to impact in a flight attitude. How ? Who knows, maybe jsut luck, maybe flat spin or similar

But they did look at LKP. The first air searches (supposedly) did so, and found no wreckage, and the first pinger searches also covered that area and came up blank IIRC. This latest successful search was going back over old ground, not searching new areas.


Now, if you want to do the real conspiracy theory, what is they logical conclusion if at the fourth time of looking you find something right where you looked the first time and didn't find it ? How long would it take to create convincing fake recorder data (they've done that before, right ?) and chop up enough bus bits and drop on them the bottom ? A year or so maybe ? And for the clincher, why aren't there any public photos of recognisable bodies or personal effects ? - because they wouldn't be there in a fake wreck! :E

Sad to say, but what volatile fuel for the conspiracy theorists, casing but no memory module :hmm:

re: HF slot antenna for the C130
 

Thanks for the link, RR. That same Brit ex-pat, Ben Hornby, consulted with the inventors of this antenna. It must have been his last project.

They have also built a slot antenna for the 747-1 and -2.

The spec for the DC-10 antenna is nmt 8 milliohms, while for the 767 it was on the order of 35 milliohms. Divide that into 400 watts, and you see the difference in efficiency.

jcjeant and bearfoil,

Interim Reports are, as I understand it, an attempt to supply information on known facts; not to indulge in theories. We can do the latter because we owe no responsibility to anyone except ourselves. The BEA does not have that luxury.

In their analysis of previous instances of unreliable airspeed indications, they discuss the instances of stall warnings (and criteria for same) at some length.

On a slightly different note: I subscribe to the theory that, if anything goes less than well in any human activity, it's generally due to what we Brits call "cock-up" (a shooting term) rather than conspiracy. I refer, of course, to the investigation; not the accident.

Granted that a lot is at stake here: not only for Airbus, Air France and the BEA. We will continue to try and keep them all on their toes, directly or indirectly. As for my own meagre (and sometimes flawed) contributions: my previous years of posts frequently include fundamental criticisms of Airbus design, as CONF_iture can tell you.


PS (Edit)

bearfoil, quote:
"Of course. LKP was the beginning of the problem, and the airbus cannot fall straight down, nor can it lose bits, so "we" plan accordingly, and perhaps reject preliminarily some critical data."

That's quite an accusation. I think you should tell us what data you are referring to.

CONF iture:

A pitch up/down moment in response to power changes is always to be expected in a conventional aircraft. However, the A330 is a 'fly by wire' aircraft and as I understand it, pitch changes with power are 'ironed out' by the fly by wire system. For example, on the B777, also fly by wire, the a/c has to be positively rotated into a climb attitude on a go-round, as the natural pitch up is removed by the PFCs. If AF447 was in a degraded flight control mode, the crew may have encountered an entirely unexpected pitch change, with power change, if they inadvertently entered a CB.
It is encouraging that the FDR module, although missing the CSMU, is not buried in silt to any extent. I do not see any footprints or scrape marks around the the FDR housing, so not much for any conspiracy theorists to go on.

Recorder but no memory module - isn't this unprecedented??

And to ChristaanJ, I surely hope you have better girl-spotting skills than planes :) The A330 is a catfish - the 777 is a horizontal spacecraft!

Hi,

Regretable that we have not another photo of this frame after it is moved by the ROV ... because the part supporting the memory module is partially buried in mud ...

http://i55.tinypic.com/2pq3pcl.jpg