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AF 447 Search to resume

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AF 447 Search to resume

Old 23rd Jul 2010, 21:58
  #1801 (permalink)  
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Ten feet, and I wrote ......second (s).
In what universe are Santa Clara and Georgia "nanoseconds" apart? Inquiring minds want to know.

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Old 23rd Jul 2010, 22:08
  #1802 (permalink)  
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keitaidenwa, ADS-B sounds like an interesting solution. It has some potentially devastating problems associated with its general use. The chief problem is the ability to spoof the system by introducing transmissions for phantom aircraft among the ADS-B transmissions from legitimate aircraft. If that's solved AND the range is sufficient, this would be good for routes that have suitable traffic. For AF447 it might have worked. Some folks here have mentioned being the only plane out over portions of the South Pacific for most of his flight. I believe a Chile to Oz route would enjoy such levels of flight infrequency. Then what?

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Old 23rd Jul 2010, 22:22
  #1803 (permalink)  
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KMD, the DC to 30kHz RF spectrum is pretty much the property of the USN simply because the USN spent the money to build the antennas required to operate in that region of the spectrum efficiently. There may be some other nations who have built transmitters in that region. I don't know if Canada has or not. Doing so reads to this USAian to be outside of typical Canadian character. I could be wrong.

These days those transmitters are deprecated in favor of satellite hops. (Outside of littoral waters hiding a submarine under water is close to impossible these days. Satellite photography reveals their locations with wonderful huge arrows painted on the water surface from their underwater wakes. The Navy REALLY does not like to talk about that, for fairly easy to understand reasons.)

Note that at least for a while NIST maintained a time standards broadcast on 20kHz-26kHz FSK, WWVL. That service has terminated with WWVB at 60KHz being the VLF service today. So the USN clearly does not have a lock on everything below 500kHz. It may seem that way. People have mostly forgotten that those frequencies can be used with exceptional ranges if you devote enough wire to the antenna. For an extreme antenna example check out "Jim Creek". For a smaller example check out WWVB's antenna.

For sonar - there is no way the USN could snarf up everything below 500kHz. There is no international allocation body to allow that. And it would effectively turn off two and a quarter bazillion fishing sonars, bottom obstruction avoidance sonars, and all the other private sonar uses.

(I've babbled too much already - I'll be quiet for awhile unless specifically addressed.)
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Old 23rd Jul 2010, 22:31
  #1804 (permalink)  
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Originally Posted by JD-EE View Post
KMD, the DC to 30kHz RF spectrum is pretty much the property of the USN....
I thought we just established we were talking about the audio spectrum, not the RF spectrum ??

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Old 23rd Jul 2010, 22:42
  #1805 (permalink)  
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The final Report of the ICAO ELT Task Force of August 2005 can be found at

ICAO ELT Task Force Report

and even though an Automatic Fixed ELT is mandatory, the report makes it quite clear that should an aircraft sink, the moment the antenna becomes submerged it is ineffective.

So that's what happened to it.

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Old 23rd Jul 2010, 22:46
  #1806 (permalink)  
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It (the primary(?) ELT) went to the bottom of the Equtorial Atlantic with the rest of the wreckage. As it got to greater depths the bits that had airpockets were crushed. That's what happened to it.
the moment the antenna becomes submerged it is ineffective.
This not supposed to be a floating device ?
And if this floating device is inside the aircraft ... it's another utter non-sens ...
For the Airbus ... better to put it on the exterior of the vertical stabilizer .. it's the only part of this aircraft who always float after a crash at sea .......
Otherwise .. it's plenty auto- release systems working by hydrostatic press ... maybe it's too much sophisticated for the aviation world ?? .. but it work great in the naval world ......

Last edited by jcjeant; 23rd Jul 2010 at 22:56.
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Old 23rd Jul 2010, 23:21
  #1807 (permalink)  
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jcjeant wrote:-

This not supposed to be a floating device ?
In the case of Airbus, it would seem logical to place the Automatic Fixed ELT in the Vertical Stabilizer. It has been proven that that part of the aircraft will survive impact with both terra firma and terra oceania. My understanding is that the device is currently located in the A330 on stringers above the cabin. Maybe someone has seen a photo showing the actual location of the ELT antenna?

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Old 24th Jul 2010, 00:02
  #1808 (permalink)  
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Hi. I was merely comparing the need for a landslide of data on demand, and the presence of two black boxes that must be retrieved to be of any use. A setting of Mayday on the Tx, or a button push in concert with a distress call could rapidly send all the data needed for forensic reconstruction of flight, (accident). No perpetual transmission is needed, merely the pilot's sending, or the a/c sending a data dump at Law switch. The need for a concentrated "Loop" of pertinent flight data is far, far less expensive than a constant drone of completely unnecessary recordings.

You don't like my idea? Tagged Air Computed Airspeed. TACA. It's proprietary, but it makes pitots completely ballast.

The nano-nano came from a discussion I was having with my brother, the cosmologist. Plus a wager on who would take the time to compute the metrics.

From a land where Light cannot get out of its own way, actually.

Mois Aider = M'Aider, meaning "help (aid, or assist me)" pronounced "May Day".
Apropos the etiology given we discuss a French tragedie.

rgds, bear
Old 24th Jul 2010, 01:20
  #1809 (permalink)  
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According to the following diagram :

the ELT antenna could be this one :

Photos: Airbus A330-243 Aircraft Pictures | Airliners.net

I am also a bit surprised by the following quote from the BEA report :
An ELT distress beacon with manual tripping was also recovered. This had not been actuated. Its switch was found in the “OFF” position.
... would be nice to have a picture of that device.

On the A330s I know, there are 3 ELTs :
  1. One is fixed and activates on impact :

  2. The other two are portable and automatically activate by simple immersion in the water (no manual switch of any kind).
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Old 24th Jul 2010, 01:24
  #1810 (permalink)  
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jcjeant wrote:

This not supposed to be a floating device ?

Not a pilot, eh?

I've been around since ELT's were first required in the US. They have never been designed to float. As a matter of fact they are supposed to be installed securely in a section of the plane likely NOT to get crushed in an accident.

Detachable, floating "rescue beacons" are a more recent boat derivations of the aircraft ELT.

The ELT was originally designed to help find aircraft that crashed while NOT in radar contact OVER LAND i.e. "who knows where they crashed". As jet aircraft and airliners were assumed to always be on a flight plan / under radar observation, and as aircraft truly, rarely "fall out of the sky" the risk of not being able to find overwater flights was of minimal concern. Until recently US registered jet aircraft did not require ELT's to even be installed!

Is it time to update "crash locator" abilities / requirements? That's for others to decide. Even if new and upgraded units with oceanic "survivability" You can bet that EVERY airline will dig in its heels at the expense and will only do it grudgeingly if mandated.

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Old 24th Jul 2010, 07:36
  #1811 (permalink)  
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Type of portable ELT

Two type of paortable ELTs are installed on Air France fleet :
CEIS S06 : http://www.ceis.com/uk/fiches/03SO6/1SO6/f_1SO6.html


ADT 406S :

Both ELTs need to be switched ON manually to begin transmission.
The CEIS S06 has an ON/OFF switch that needs to be used.
The ADT 406S has an ON/ARMED/OFF switch.
The ARMED position is arming the hydraulic switch that allows the ELT to transmit once the switch is activated by some kind of liquid.
So the ADT 406 can be water activated only after it has been put in the ARMED mode.

This is video (french) showing the ADT406S : Dailymotion - Julie CFS - une vidéo Vie pratique

Last edited by pgroell; 24th Jul 2010 at 12:24.
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Old 24th Jul 2010, 22:13
  #1812 (permalink)  
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CONF iture;

Thanks for the photo and ELT antenna location schematic. Realized after seeing it that I already had the same drawing!


The links to the Air France fitted ELT types are appreciated, though the most important link came up with "Page not found". The correct link is:-

Emergency Locator Transmitters

Scroll down to the bottom of the page and there are 6 links to the various ELTs available. The pop-up windows are also scrollable, and some include links to additional windows/pages.

The Automatic Fixed type is fitted with a "g" switch, and though details of its operation are not included, the specification calls for the switch to operate when subject to an acceleration of 5g or greater for at least 11 milliseconds in any vector. The GEOSAR satellites covering the position of the AF447 crash are the Meteosat Second Generation geostationary satellites MSG-1 at 9.5° E, MSG-2 at 0° and GOES-12 at 75°W.

Modified GEOSAR Coverage Map

Once activated the ELT will transmit a 0.5 second data stream on 406.025MHz every 50 seconds, but in this case, I suspect the departing Vertical Stabilizer removed the ELT antenna before the first data burst was complete.

EDIT:: Bearing in mind that following activation, no carrier is transmitted during the first 50 seconds, then the first 0.5sec data stream is sent to commence the normal 50 second cycles. So the antenna was by then either missing or submerged.


Last edited by mm43; 25th Jul 2010 at 14:21. Reason: modified EDIT
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Old 25th Jul 2010, 00:29
  #1813 (permalink)  
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It's very frustrating that from the first ACAR message to the second after the AF447 touch water .. nothing on this plane (a nest of high technology) worked as expected ( or worked as expected ???)
And to today all the explainations about the possibles reasons of the crash or the explainations about the failures to find the remains of the plane are at least foggiest.
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Old 25th Jul 2010, 09:09
  #1814 (permalink)  
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AF447 search

Finding things on the sea bottom is incredibly dificult, especially given the conditions where AF447 crashed. In fact even finding something on the sea's surface is very difficult. One is dealing with a totally alien environment (which does not seem to be the case at first glance). Paitence, gentlemen patience.
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Old 25th Jul 2010, 14:48
  #1815 (permalink)  
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Finding things on the sea bottom is incredibly dificult, especially given the conditions where AF447 crashed. In fact even finding something on the sea's surface is very difficult
But finding something on the sea surface emitting and signaling his position is far more easy.
So it's frustrating that all the (expensives) brains working for the devellopement for a "safest" aviation world had not yet (or want not) design a reliable device able to float and send his position when a plane crash at sea ...
Remind me .. we .. humans .. were able to go and land on the Moon and return !!! ...
Do we need to revamp the wheel ? .. or it's a "no will" ?
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Old 25th Jul 2010, 23:02
  #1816 (permalink)  
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Lessons learned

From AF447 and Adam Air 574 (and others) we have learned it can be many days before the wreckage of an aircraft traveling in an oceanic environment is localized. This uncertainty significantly increases the cost of recovery efforts and practically guarantees that there can be no survivors.
  1. Why do we not require commercial aircraft traveling in an oceanic environment to have a floating ELT capable of detaching from the aircraft and floating to the surface? We have a capable SAR network. Why not have a means of employing it?
  2. The expense and problems of oceanic data recovery indicate that we need to store data in a less concentrated fashion than we presently do. What is to prevent a black box from outputting its data (as it is recorded) to a secondary/tertiary/etc recording device mounted elsewhere on the aircraft. Then all the eggs aren't in one basket. If you mounted one of the storage devices on the floating ELT discussed above, the cost of oceanic crash investigations could be reduced by orders of magnitude with just a little good fortune.
  3. Secondary data storage devices would be shock hardened but not armor plated. They would probably be located in the vertical stabilizer and wing tip vicinity. From previous discussions, it appears that the satellite route to data recovery isn't ready for prime time.
If AF447 teaches us any easy lessons, they are that our existing systems for crash location and crash data recovery need improvement.
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Old 25th Jul 2010, 23:28
  #1817 (permalink)  
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Airbus software

I've been thinking about the programming for fly-by-wire aircraft and the software conditional branches to contend with flying close to coffin corner, encountering a major thunderstorm and possibly losing some real-time physical status input. When Windows encounters this kind of situation and gives me the blue screen of death, I can just hit the reset button and restart to a known condition, except on newer machines where you have to disconnect the battery because there is no reset button. Does fly-by-wire hardware have a reset button anywhere close to a human in the cockpit or is it necessary to find a circuit breaker somewhere? Perhaps some professional pilot could answer this.

Last edited by kilomikedelta; 25th Jul 2010 at 23:47. Reason: clarity
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Old 26th Jul 2010, 01:39
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Machinbird wrote:-

From AF447 and Adam Air 574 (and others) we have learned it can be many days before the wreckage of an aircraft traveling in an oceanic environment is localized. This uncertainty significantly increases the cost of recovery efforts and practically guarantees that there can be no survivors.
There is absolutely no doubt that being able to localize the last known position of any aircraft (in any FIR) is paramount.
  1. There seems to be a growing use of ADS-B where the costs of SSR installations in remote Land FIRs is prohibitive. Parts of Canada and Australia are examples where ADS-B has been incorporated into their respective country's ATC structure.
  2. Security from spoofing of IDs is a matter that needs urgent attention, and can probably be dealt with by adding a couple of encryption fields to the data currently transmitted. But even in its current form, ADS-B satellite monitoring of selected flights would be a worthwhile enhancement from an SAR stand-point - especially in remote Land/Oceanic FIRs.
  3. Once again, the infrastructure doesn't exist, but would be a cheaper option than a redesign and retrofit of EPIRB/GEPIRB ejectible/floatible devices, and all commercial aircraft would benefit. Problem is that at least 3 geostationary satellites need to be fitted with an ADS-B package, and I envisage we are still looking at a 10 year delay.
Further back in this thread there has been mention made of secondary data storage devices, and at least one incorporated into the Vertical Stabilizer would certainly have been of benefit in the case of AF447. Likewise, an Automatic Fixed ELT in the V/S.

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Old 28th Jul 2010, 18:48
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Bearfoil (re 1810), satellite radios don't work every time. As a near life long amateur radio operator radios don't work a staggering amount of the time somewhere in the world. HF relies on the vagaries of ionospheric bending. VHF goes right through the ionosphere except in strange equatorial conditions when it ducts and you get taxi radio interference with taxis in the ducts in Hawaii and Southern California. VLF works over long distances if you invest in enough wire. You can't do high data rates for burst transmissions, though. Heck, that is a problem on HF, too. Multipath ruins most fast transmission modes. 10,000 bps is blazing fast for HF and requires a not insignificant amount of time to achieve lock.

Worst of all, satellites are not there when you need them. If your first awareness of a problem is the plane falls off on a wing in a massive stall - and ACARS goes off beam to the satellite. Worst yet, you are about mid way on a route between Perth and any place in South America - you are over the South Pole. You have no satellites to speak with. Look at mm43's satellite coverage maps a few messages on.
Now duplicate this on any of the air routes over the North Pole.

Add in auroras and HF goes dead for you. And on a guess I'd not want a substantial fraction of a mile of wire hanging out in aurora conditions unless there was a REALLY good way to drain off static electricity. But that last detail I am not sure about. It's an honest hunch. VLF might get through the auroral murk.

If, while you are out of contact with ANYBODY all alone for hundreds of miles in any direction who will hear your emergency transmission on 121.5 MHz or 405MHz or even 2175kHz?

This is why I wonder, "What expense is worth itself as a partial solution to the missing flight data situation?" A patch here to solve AF447 still leaves us open somewhere else if it relies on data transmission to satellites or passing ships or nearby aircraft.

I also note that so far as I know it is "easy" by some definitions of easy to transmit a mayday on 121.5 MHz and supposedly every plane in the air is monitoring the frequency. Nothing was heard. Was a transmission attempted and swamped out by various kinds of static discharges in the area a couple hundred miles around the aircraft? If the plane happened to be in a duct there could have been nobody at any place along the duct to hear it. And nearby planes would be less likely to hear it due to attenuation - signal lost to propagate in the duct.

Radio is a nice solution. I do not believe it is a comprehensive solution to this problem as proposed so far. Modified ELTs for over water use might be a good radio solution, however. (I'd propose "ejected on impacts more than 3g, floats, is wired into navigation to receive up to the second updates, and transmits that location every 20 minutes at 50 mW on 121.5 MHz FM using APRS formats. Then I'd work out the math to see if it really would work and could be setup to both float, survive impacts, and last a month.)

But none of this finds AF447 for us. It "only" makes it harder to recreate some lost recorders situations.
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Old 2nd Aug 2010, 11:37
  #1820 (permalink)  
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Has any date been proposed for the search to continue. As time goes by, it will not be any easier. Anybody else got that doudting feeling?
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