Simplest ideas are usually the quickest to deploy, and often the most reliable.

Place one or more blocks of bog-standard marker dye under seats or behind panels.

The passenger compartment invariably breaks up on striking the sea surface or is crushed by depth pressure, thus exposing the dye to water and starting a trail in the sea current.

Any airline could do this right away as a voluntary measure. Very little design required, no airframe changes, no type approval or certification.

The extra weight? Probably no more than a couple of bottles of booze.

Sallyann1234,
Do you know any technical details about the stuff (I don't, which is why I ask)?
How much would you need for a really big stain that persists for a couple of days in a heavy swell?
And wouldn't it be affected by wind and current in the same way as debris?

And talking debris, how often does an aircraft end up in the water without leaving at least some debris on the surface anyway?
In the case of AF447 there was an entire tailplane... it still did not help in finding the sunken wreckage, leave alone the FDR and CVR.

CJ

I hope the Brazilians have finally gotten around to doing the forensics on the bodies. This would give some idea of the speed at impact, and what happened to the fuselage, and what to look for. My guess is the speed wasn't that fast and the plane broke into several large chunks.

To give you all an idea of what is being sought, this is how small the FDR is.....

This one is still attached to the ROV that recovered it.http://i23.photobucket.com/albums/b3...lack_box_c.jpg

HamishMcBush,
Even shorther than some I've seen and handled......
Do we know the type of the FDR on AF447?

This is assuming the FDR broke free of the fuselage which it probably didn't. That's why they couldn't hear the pinger - it is enclosed in a piece of the plane which is lying on the seabed, like the Titanic.

In response to the following:-

-@UA
-Juste wondering if you could comment about the order of magnitude of the -cost involved in operating such vessel ? Also what would be the typical -mission for this type of equipment ? Telecom cables ? (very) deep offshore -rigs ? scientific ?

Not willing to go into costs at this stage other than to say that the whole spread (vessel, WROV, deep tow sonar & personnel is considerably sub £100k per day.)

Typical workscope for such a sonar spread is pretty much as you state above, scientific, deep wreck search, deep telecoms cables, pipeline route survey, not rig related however at those depths.


-@UA
-I don't know either, whether you can comment on some of the issues?

-Do we even know where the debris field is?

-What's the resolution of the sonar? How easy or difficult is it to distinguish -a piece of 'man-made' debris from the rock next to it?

-It's unlikely the FDR and CVR were thrown clear from the rest of the -wreckage... more likely they're still stuck in some of the aircraft structure. -So much the same question... you're not looking for rectangular boxes, but -for the most likely parts of the wreckage. Can the kind of sonar you mention -find those?

-You obviously would not send a ROV down until you had at least some kind -of target, no?

A working group is currently in place to identify the search area.

Typically, given the length of cable behind the tow vessel (upto circa 10,000m) a series of runs will be made within a box, once the box is complete any targets identified by the sonar passes will then be investigated by the WROV.
It is not a case of differentiating between simply 'black boxes' and rocks, any wreck be it aircraft or ship will leave a debris field, usually over quite a large area. Such an area would be rather obvious and would warrant further investigation with the WROV using both video and hi-res multibeam sonar to map the debris field. Such a hi-res multibeam system can pick out items as small as a coke can.

@christiaanJ
I have seen marker dye deployed from a liferaft during a maritime exercise. The distance that it could be seen from the air was amazing - long before the raft itself was seen. The size and profile of the raft was not too dissimilar to the floating debris from an aircraft.

I'm suggesting that the dye capsule would be secured within the airframe, so that the marker train originates from the seabed location rather than from the floating debris.

I was fortunate to be involved in a conversation with a senior manager at the company where I work today. I am told that the company I work for is putting pressure on the airline industry to update the 30+ year old technology used by the pinger system and to aim to have FDR's use a transponder system, so they will not transmit until interrogated. This will mean that the battery life will increase, to up to 5 years.
We can do with support from those in the aviation industry to take this further, I am sure.

Sally Ann,

Thanks, sounds like another halfway sensible idea worth exploring?

As you said, the equivalent of a few bottles of booze spread through the aircraft might do the job.

Still, I'm less convinced that a "marker trail" from a wreck 4000m down wouldn't totally diffuse before it got to the surface, or wouldn't be so far displaced by currents, that it would not be any rel help.

CJ

But better than no help, surely...

It is simple and probably effective and better than not having that capability, no?

RE: Tracer Dyes. These are often designed so that even if the dye isn't visibile to the naked eye by exposing a sample of water to UV light the dye glows in a way that can be detected electronically.

In this way the dye can still be detected when it is diluted down to levels way below is being visible to the naked eye. In fact in some situations where they are used this is the preferred method. For example releasing the dye into a stream at the start of a cave network and sampling the rivers coming out of the caves to see if they are connected. The locals tend to get funny if you turn the whole rivers purple, hence using dyes at levels to be invisible to the naked eye, but still detectable is standard practise.

So in the AF scenario by taking samples of surface water and testing for presence of the dye over a very wide area you could find traces and focus the search in to the areas with the highest concentrations.

How long would this take in this search?

Agreed. Chemical analysis would not be practical.

I envisage a slick of dye emerging on the surface downstream of the wreckage on the seabed, which in clear weather would be visible to a wide-area search more quickly than pieces of floating debris. It only needs to be there long enough for the first search plane on the scene to record the GPS coordinates of the start and end of the slick, allowing a pretty good extrapolation to the seabed location.

I don't pretend for a moment that this would be foolproof, but it could be a valuable extra pointer to the location of the FDR.

Emergency Buoy
 

How about a really long tether fastened to the fin and fuselage:}

just how long do you propose this lanyard to be?






gs

Guys IT WILL NEVER BE FOUND !

It's in Airbus and Air France best interest for it NOT to be found.

Look at the BIG picture Luke :sad:

Oh come on Flyboy...

If you'd been following the story properly, you'd be already aware of the precursor events, and the amount of neglicence being demonstrated thereby....

Getting hold of the FDR and CVR would at least narrow down the story.
It might even allow the "perpetrators" to blame it all on the crew.

So put some more peanut butter on your tinfoil hat, and let it be.

CJ

Anyone have an idea about in how many cases, say in the last 30 years, the boxes have not been recovered or the data had been destroyed beyond being of any use?

By Simon Hradecky, created Friday, Nov 20th 2009 14:30Z, last updated Friday, Nov 20th 2009 14:30ZA US Airways Airbus A330-300, flight US-740 from Philadelphia,PA (USA) to Madrid,SP (Spain), was enroute at FL390 about 350nm east of Philadelphia overhead the Atlantic about 40 minutes into the flight, when the crew announced they needed to return and was cleared to turn to the left. About 40 seconds later during the turn the crew declared emergency and requested to descend. About another 5 minutes later while levelling at FL300 the crew reported, that everything had returned to normal explaining, that they had experienced computer problems they were unable to resolve and they had been "missing control". The emergency was cancelled, the airplane continued back to Philadelphia. The airplane landed safely on Philadelphia's runway 09R about 75 minutes after the onset of trouble.