Tech Log The very best in practical technical discussion on the web


Old 23rd Jun 2009, 12:35
  #2201 (permalink)  
Join Date: Apr 2009
Location: US
Posts: 120
Likes: 0
Received 0 Likes on 0 Posts
I am having trouble understanding the fact the french or indeed any military cannot detect the signals from these boxes.

The Submariners, IIRC, spend most of their lives trying to track down the "enemy" that is hiding, yet they are having difficulty detecting something that "wants to be found", that is sending out a pinger signal for a over 3 weeks.

Come next month will we be greeted with the garlic shrug and "non"?

Please feel free to shoot me down in flames, should I need to be.
screwballburling is offline  
Old 23rd Jun 2009, 12:42
  #2202 (permalink)  
Join Date: Mar 2008
Location: Frankfurt
Age: 48
Posts: 43
Likes: 0
Received 0 Likes on 0 Posts
.....if they send out signals at all that is!
CptRegionalJet is offline  
Old 23rd Jun 2009, 12:57
  #2203 (permalink)  
Join Date: Jun 2009
Location: Belfast
Age: 46
Posts: 21
Likes: 0
Received 0 Likes on 0 Posts

Thanks for your reply. I thought the source was reputable enough, it's a very well regarded and generally well-researched series (Air Crash Investigation). The fact someone put it up on youtube shouldn't lessen it's reputation. But granted, it may not contain the amount of detail that the full report does.

I should probably not have said anything until more solid info becomes available, and I apologise for the conjecture. That said, I'm sure you can see where I was coming from.
Poit is offline  
Old 23rd Jun 2009, 13:02
  #2204 (permalink)  
Ecce Homo! Loquitur...
Join Date: Jul 2000
Location: Peripatetic
Posts: 17,327
Received 1,543 Likes on 705 Posts
I am having trouble understanding the fact the french or indeed any military cannot detect the signals from these boxes.
The ocean has layers of different temperature and salinity. These can act, for sound waves, in the same way a prism or mirror acts for a light wave - refraction and reflection.

Some sounds can be reflected between layers and travel across thousands of miles. Others can be emitted from just a few hundred feet below and not heard within a few miles.

Now consider a black box under 6000+ feet of water with multiple layers between it and the surface. take a submarine with a crush depth of less than a thousand feet. take a couple of submersibles with a greater crush depth, but miniscule range and no sonar.

Now consider how lucky one must be to detect the signal, and if detected, to locate the source.

I would have thought their best chance of a detection was the SOSUS chain.
ORAC is offline  
Old 23rd Jun 2009, 13:16
  #2205 (permalink)  
Join Date: Mar 2003
Location: BC
Age: 76
Posts: 2,484
Received 0 Likes on 0 Posts

Your post very well-stated and balanced. Ninety-nine percent of the time it isn't an issue, but each flight is different and it is up to the captain to determine how the flight will be handled.

I don't think the issue requires the sweeping comments as some who disagree with you have provided - more subtlety, borne of experience in doing this kind of flying, is needed to understand what is being said. It isn't a matter of trust, or being over-bearing, it is a matter of assessing all factors within an environment in which a high degree of competence and skill already exists. A brand-new CRP (Cruise Relief Pilot - not permitted to occupy the front seats below cruise), who has just passed all the airline's requirements isn't as competent as a CRP who has flown extensively in these areas either in a previous life or as CRP for a few years, and as a captain I would (and quietly did) assess enroute weather and judge that accordingly, as I should.

In my experience, the proper use of airborne radar is not taught and not every pilot is equally "into the books". (I wrote the post on radar on the other thread for this reason.) If there is weather enroute, I think that is an important bit of knowledge to establish and was one factor among many which I quietly assessed before taking my break. It was never as black-and-white as some have characterized.

'nuff thread drift. Re the pingers - Damn.
PJ2 is offline  
Old 23rd Jun 2009, 13:18
  #2206 (permalink)  
I don't own this space under my name. I should have leased it while I still could
Join Date: Dec 2002
Location: Lincolnshire
Age: 80
Posts: 16,777
Received 5 Likes on 5 Posts
Originally Posted by ORAC
I would have thought their best chance of a detection was the SOSUS chain.
If it is still operational.

Back to the original post. A towed sonar array would possibly need to be within 6000 feet of the source. That gives a swept width of just 2 miles. Allowing for overlap you are probably looking at a track spacing of 1.5 miles. To detect a source using a towed array I would guess no more than 9 kts - let us say 6 kts then. It would take 10 hours for one 60 mile sweep. It would take 60 hours to clear a box just 10 miles x 60.

Then you must factor in water depth. No good with your sensor at more than 6000 feet off the bottom.

If you imagine the ditching or crash distance of 15 miles in relation to track you are looking at a box 30 x 60 or 180 hours. That is over one week to sweep one box with no better than 70% probability.
Pontius Navigator is offline  
Old 23rd Jun 2009, 13:31
  #2207 (permalink)  
Join Date: Feb 2008
Location: USA
Posts: 37
Likes: 0
Received 0 Likes on 0 Posts

I still like best the idea that was put forward earlier in this thread: simply put the recorders inside the vertical stabilizer. It seems that portion of many airplanes is usually still recognizable after a crash, and it appears that the VS already has an inherent "release & float" characteristic.
Orestes is offline  
Old 23rd Jun 2009, 13:41
  #2208 (permalink)  
Join Date: Apr 2009
Location: US
Posts: 120
Likes: 0
Received 0 Likes on 0 Posts
Thanks for the information on the inherent difficulties of detecting the signals from these boxes.

Placing them in the vertical stabilizer seems like a good idea. I think the authorities may have to look at redesigning the whole Sonia detection signal, strength and relocation of the BB's etc.

There has to be a better way than the installation and location, than at present.

Are we all going to have to wait for the next prang, in order to try and find out what may have happened in this tragedy?
screwballburling is offline  
Old 23rd Jun 2009, 13:42
  #2209 (permalink)  
Join Date: Nov 2001
Location: UK
Age: 70
Posts: 76
Likes: 0
Received 0 Likes on 0 Posts
FDR & CVR – Why don’t they float, they don’t have to but it would be really useful if the memory modules did and what’s more, think 16GB USB stick, wouldn’t it be useful if the data was ported to more than one memory module and both voice and flight data were recorded on the same module.
Now the memory is so small it should be able to fit in just about anywhere, even wireless is possible.

One thought on the current situation. If the aircraft broke up and the rear section is partially intact, perhaps with the rear bulkhead still in place, it may actually be floating sub-surface due to trapped air and the recorders may not be immersed and therefore, not pinging but perhaps transmitting.

One item mentioned earlier – the press in emergency button, which would ACARS and transmit an automatic position report/heading/speed/altitude and keep doing it until cancelled is a brilliant idea, should be one on every joystick.

Can you imagine what would have happened if they had managed a successful ditching but not been able to talk to ATC or Paris first.

Lastly, I wouldn't rule out those other sounds, unfortunately fish and probably squid will be attracted to the wreck and whales of course eat squid so definitely listen for them.

Last edited by Backoffice; 23rd Jun 2009 at 16:11.
Backoffice is offline  
Old 23rd Jun 2009, 13:44
  #2210 (permalink)  
Join Date: Feb 2006
Location: On the big blue planet
Posts: 1,027
Received 24 Likes on 12 Posts
Mrs 22/04 said to me last night; why don't the recorders float; they could then be recovered with the seats bodies etc.

Set me thinking- put them in a box that it triggerd to release or eject by presence of water and pressure (depth) - is this a viable idea?
Wouldnt be new, the famous Lockheed 104 Starfighter had such device, an airfoil shaped floatable container behind the cockpit on top of the fuselage...

skadi is offline  
Old 23rd Jun 2009, 14:01
  #2211 (permalink)  
I don't own this space under my name. I should have leased it while I still could
Join Date: Dec 2002
Location: Lincolnshire
Age: 80
Posts: 16,777
Received 5 Likes on 5 Posts
If the FDR and CVR floated you would need to add positional information too so that the crash location was marked. At present, the FDR usually marks the crash site too.
Pontius Navigator is offline  
Old 23rd Jun 2009, 14:13
  #2212 (permalink)  
Join Date: Nov 2006
Location: SoCalif
Posts: 896
Likes: 0
Received 0 Likes on 0 Posts
Fortunately, the need for deep water recovery of the boxes is very rare. Rather than more crash recorders, I would put more money into pitot probes that don't ice up, AOA sensors that don't put out noise spikes, and ADIRU that don't get fooled.

Graybeard is offline  
Old 23rd Jun 2009, 14:15
  #2213 (permalink)  
Join Date: Oct 2001
Location: Gatwick
Posts: 1,980
Likes: 0
Received 0 Likes on 0 Posts
Or a rethink of the currently fitted ELT's!
Litebulbs is offline  
Old 23rd Jun 2009, 15:27
  #2214 (permalink)  
Join Date: May 2009
Location: China (CGO)
Age: 75
Posts: 164
Likes: 0
Received 0 Likes on 0 Posts
Slightly Less Dirty Translation of Le Monde Article

The link was kindly posted on page 110 here. It was updated at 1150LT (Paris), five hours after the first version went online.

The bottomline is somebody heard a noise but no confirmation it was from any blackbox.


French naval vessels captured a very weak signal. It was thought it might be from the black boxes. The Nautile was sent down on June 22 to attempt a recovery, expected to be difficult because of their location in the aircraft.

A BEA spokesman said the blackboxes had not been precisely located.

Ifremer Captain Philippe Guillemet of the "Pourquoi Pas" search ship said: "We're still looking...We get acoustic signals but none have been validated. Unfortunately."

Asked: "You haven't located the blackboxes at all?", Guillemet replied: "Absolutely."

The article then notes the blackboxes can be heard only up to 2 km away and that the seabottom is rough terrain at 5,000m depth.

It adds the blackboxes will ping for about eight more days; the next paragraph moves on to the identification of 11 bodies.


Last edited by ArthurBorges; 23rd Jun 2009 at 15:52. Reason: Mistakes!
ArthurBorges is offline  
Old 23rd Jun 2009, 15:51
  #2215 (permalink)  
Join Date: Jul 2000
Location: Texas
Age: 68
Posts: 18
Likes: 0
Received 0 Likes on 0 Posts
Relief Pilots

I can only add my hours as experience as a International Captain for a Major Airline. All our FO's at our airline have been here for quite a while. I would not have a problem taking a nap during my rest cycle. However that was not always the case.

Several years ago when we were hiring we were putting guys into the right seat of the 757 and 767 aircraft into the International Division. A fellow Captain had told me that he just got through flying to LGW from DFW with 2 newbie's in the 2nd and 3rd seat. He told me he took his break in the cockpit just to make sure.

Well it comes my turn and I get called out to fly to ZRH. Meeting the 2 FO's in operations I noted that when I signed in for the trip the FO had 139 hrs in the 767 and the FB (extra First Officer) only had about 50+. This was not their total flying time however, just since they started flying for us and the time that they had in the 757/767 Fleet.

They were young guys probably mid to late 20's straight from the commuters with no jet experience at all much less flying a heavy aircraft across the pond over to Europe and beyond. I would be by myself for the most part.

Needless to say I did not take my break in the back. I simply couldn't let these two young guys get in over their heads while trying to coast out and follow the North Atlantic Track Procedures. I let them do as much as they could but they really were in over there heads experience wise.

Sometimes airlines rush to put people into certain positions simply because they can. They rely a lot on experienced Captains and experienced First Officers to pass their knowledge along to the next guy. Sometimes you get this gut feeling and you just have to make the best decision that you can. Even if you step on someone's toes. You are responsible for everything and everyone is counting on you.

Who was in the Cockpit on the Air France Flight? No one knows at this time. Only when and if they recover the CVR will they know. And lets only hope that they find it soon. We need the answer to this tragedy as soon as we can.
Captain Bob is offline  
Old 23rd Jun 2009, 16:09
  #2216 (permalink)  
Join Date: Jan 2008
Location: Pretty far away
Posts: 316
Likes: 0
Received 0 Likes on 0 Posts
I would opin that the unease experienced by 'experienced' captains is not due to a perceived lack of experience in their FO but from their own lack of experience in temporarily handing over their responsibility.
Sorry but that s rub...h. I ve seen it time and time again, when you re in the bunk the most amazing things happen. Not all the time. I ve flown with really outstanding F/O s who had their heads bolted the right way and this, regardless of age and origin.
Unfortunatly, I ve also experienced the worst kind, type, I m a cool dude and who the are you to dare telling me what I need to do. By the way, what s keeping you from upgrading my wife and kids right now ????
They are not the majority but they are enough to poison the well. What will management do ??? Actually nothing since the word for the lat 10 years has been " Do not rock the boat old boy, or you re the one who is going to get hurt ".
This might be totally unrelated with what happened to 447 but it gets people talking about their own experience and I find this telling.
By the way, some F/O s are also very relieved when the skipper goes to sleep..................and for some very good reasons too.
Me Myself is offline  
Old 23rd Jun 2009, 16:50
  #2217 (permalink)  
Join Date: Jun 2009
Location: France
Age: 76
Posts: 196
Likes: 0
Received 1 Like on 1 Post
If what Weopons Hot made you nervous, exercise your right of choice and only fly with carriers who don't use 2nd officers/cruise pilots.
French unions always rejected the notion of "cruise pilot" and you can be assured that the guys at the controls in AF447 were checked out satisfactorily against the same technical standards. Also, AF has a policy of not pairing low experienced pilots on the a/c type when scheduling crews.

However, I can't help feeling that the standards are no longer what they used to be.

Last edited by DJ77; 23rd Jun 2009 at 21:10.
DJ77 is offline  
Old 23rd Jun 2009, 16:53
  #2218 (permalink)  
Join Date: Sep 2001
Location: Toronto
Posts: 2,558
Received 35 Likes on 16 Posts
Hoping that they can find this black box but not looking good is it?
The usual way to find the CVR and FDR is to follow the pinger, but even in shallow water that can take several days as we saw last year with the a/c that hit the water on a handover flight.

Once the pinger battery packs it in, they will have to go to sidescan sonar. Given the irregular bottom profile and the likelihood that the section containing the CVR and FDR will be just one of many dispersed pieces, it's going to take a loooong time and a serious pile of megabucks.

But it's a doable. Ship of Gold in the Deep Blue Sea: Gary Kinder: Books documents the years of effort required to find a historic shipwreck on a flat seabottom.
RatherBeFlying is online now  
Old 23rd Jun 2009, 18:30
  #2219 (permalink)  
Join Date: Sep 1998
Location: wherever
Age: 55
Posts: 1,616
Likes: 0
Received 0 Likes on 0 Posts
Take it from me. If they have a ping it won't take long to triangulate it. Now a very big ocean is much much smaller. My bet is recovery of the recorder(s) within 3 days.
FE Hoppy is offline  
Old 23rd Jun 2009, 18:49
  #2220 (permalink)  
Join Date: Jan 2008
Location: Vancouver, BC, Canada
Posts: 33
Likes: 0
Received 0 Likes on 0 Posts
Some very interesting new photos (once clicked on the images will open in a reduced size, click on again to see a very large version):

DorianB is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.