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Air France jet missing over the Atlantic

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Member
Registered: May 2009
Posts: 772
Location: Sydney, Australia
The ISIS referred to in the alleged ACARS is the standby instrumentation (and associated sensors?)... the fact it was able to send ACARS messages advising of failures seems strangely at odds with the extent of failures - to lose so much and still have ACARS sending info... very strange...

sidetrack: Qavion, does the 777 have the same Honeywell ADIRU as the 'bus?
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Moderator
Registered: May 2009
Posts: 2449
Location: KTMB
Phil Bunch wrote
... they were advised by maintenance not to reboot the computers since it might make things worse. After the plane landed, the maintenance staff saw that the system was not working properly but after it was rebooted they could not reproduce the error condition.

Ah, normal fault-finding procedure in commercial computer operations :twisted:

It is terribly hard to diagnose a malfunctioning machine, and there may be pressure from users and management to "just fix it" which means a reboot and, usually, throwing away all evidence of what went wrong. I've seen many cases of this, and the more important the system, the less time the technicians get to play with the malfunctioning state. Only a fully redundant system that can be unplugged without consequences can be properly diagnosed, usually.

The same situation is common when systems get compromised due to a security problem (breakin, contamination, etc.). A common reflex is to wipe the disks and re-install the backup. That destroys all evidence of what caused the compromise in the first place. But, since it is a machine that has been carefully broken in to, leaving it running also has the definite possibility of destroying evidence, as it may have been booby trapped. Unplugging the network connector has been known to trigger a self destruction software device. You'd like to "freeze" the thing instantly, which is easier said than done.

I do agree that in case of a still flying airplane, an inflight reboot should be considered a measure of last resort, because you never know that it will clear the problems.


Jeroen
Member
Registered: May 2009
Posts: 125
Quote
sidetrack: Qavion, does the 777 have the same Honeywell ADIRU as the 'bus?


Sorry, John. I currently don't have access to this information. Our own airline doesn't fly 777's and has very limited exposure to foreign and other operators these days. The 777 maintenance manual I have access to doesn't mention manufacturers or p/n's.

Rgds.
Q>
Member
Registered: Jun 2009
Posts: 138
Location: Melton Mowbray. U.K.
Thanks for the replies above; very interesting reading.
Rgds
Carl
Member
Registered: May 2009
Posts: 414
Location: Mumbai, India
Quote
A typical black box memory will be encased in several layers of fairly thick metal (these boxes are quite heavy and definitely do not float) and may have a water jacket around one layer.


Okay, here's my idea. It surely can't be impossible to have another layer filled with air (or even Helium) .. the idea being that it would float to the surface of the water.

It's jammed up in other parts that won't let it rise?
Okay, since it's in the tail, it must be easy to place it in a section that breaks off on heavy to moderate impact, as surely any collision with the water would be.

If this is an old idea, sorry.
If it's a brilliant idea, make sure I get royalties, gentlemen :)
Member
Registered: May 2009
Posts: 944
Honeywell is quoted as saying that the "black box" recorders have underwater beacons that can be tracked underwater at a depth of 20,000 feet, and even from the surface. This is much more than the previous 3000 feet others had claimed.

Below is the URL for the updated article:

http://online.wsj.com/article/SB124394381881876429.html

an excerpt follows:
=====================
The smaller the search area, the faster the sound is likely to be detected. Once the signal is heard, computers can pinpoint its source quickly, so "it all depends on how deep the black boxes have gone," Mr. Cairns said.

Honeywell International Inc., the recorders' producer, said that barring unusual currents and temperatures, the signal should carry for at least 20,000 feet and may be strong enough to be picked up on the surface.
=====================
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Best wishes,

Phil Bunch
Member
Registered: May 2009
Posts: 418
Location: Australia
Quote
In intense heat, the water turns to steam, and steam generally is limited to a specific temperature range well below the intense heat of an aircraft fire.

The purpose of the water jacket is probably to limit the rate of temperature rise in the innermost compartments as it requires much more energy to convert boiling water to steam than it does to heat it from cold to boiling. The hope would be that the intense fire has died down by then. If the fire is still bruning then once the water has turned completely to steam the temperature on the inside will resume rising until it reaches the temperature on the outside.

Quote
Okay, here's my idea. It surely can't be impossible to have another layer filled with air (or even Helium) .. the idea being that it would float to the surface of the water.

For an object to float, its density has to be less than that of water. As steel is much more dense than water it would have to have a large volume of less dense material inside it, like a submarine. The 'black box' would have to be very large, with lots of empty space within for it to be able to float. Squeezing a gas into a small cavity would not work.
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Garry

Website: flightsim.garryric.com
Member
Registered: May 2009
Posts: 944
Shiv Mathur wrote
Quote
A typical black box memory will be encased in several layers of fairly thick metal (these boxes are quite heavy and definitely do not float) and may have a water jacket around one layer.


Okay, here's my idea. It surely can't be impossible to have another layer filled with air (or even Helium) .. the idea being that it would float to the surface of the water.

It's jammed up in other parts that won't let it rise?
Okay, since it's in the tail, it must be easy to place it in a section that breaks off on heavy to moderate impact, as surely any collision with the water would be.

If this is an old idea, sorry.
If it's a brilliant idea, make sure I get royalties, gentlemen :)


======================
Shiv,

I have an idea,, too! Put the recorders into rocket-assisted probes that will detach from a crashing airliner. Shoot them up a few miles and then launch the parachutes and start the flashing strobe lights, radio beacons, GPS trackers, etc. (insert many grins here)

Along somewhat the same line of thought - there are rumors that Air Force One has an escape pod for the President. No confirmation on this but it was featured in an action movie a while back.

On a more realistic note, there has been talk of having video recorders in the cockpit, not just voice recorders. That way I guess one could see what the heck is going on and/or what mistakes a pilot makes during crises. I fear the recent Buffalo icing accident/stall would not have been a pretty scene on video as he fought the stick pusher...
_______________
Best wishes,

Phil Bunch
Member
Registered: May 2009
Posts: 125
Quote
Honeywell is quoted as saying that the "black box" recorders have underwater beacons that can be tracked underwater at a depth of 20,000 feet,


My notes have a different interpretation. The operating depth of the beacon is quoted as being 20,000'. i.e. The locator beacon on the front of the DFDR/CVR is in a metal tube (about 1/8" thickness, I'd estimate). It will probably collapse at depths greater than 20,000'.
My notes also say the transmitting range varies depending on the sea water (1800~3000metres)

The old FDR weighs 30lbs, the new one 18lbs. The old CVR was 24lbs. How much helium would you need to lift this? : )

Rgds.
Q>
Member
Registered: Jun 2009
Posts: 20
Properties of the Flight Recorders:

I was a designer, with NASA, of flight electronics and the back boxes that enclose them for many years. An electronics box designed to withstand the typical G load and vibration environment of aircraft flight or spacecraft launch ends up being close to the density of water (Specific Gravity = 1). Some a little more and some a little less. Constructing an inclosure that can survive a 1000 G plus impact adds so much metal that the boxes' SG will increase to the 3 - 5 range.

One of the FR's from the Air Florida crash was found when a searcher realized that he was only knee deep in water when elsewhere the water was wast deep. He was standing on it. This FR was completely on it's own, not entangled with other structures, and obviously not floating.

I don't know how much effort is put into sealing flight recorders (FR) as air spaces are counter productive. Unless one goes to extreme measures when an air filled container sinks in a deep ocean it will eventually implode, pulverizing what ever is inside.

When a FR is recovered from water, the NTSB assumes that it is full of water. If at all possible, the wet FR is placed in a cooler, filled with the water the FR was found in without exposing the FR to air.

The underwater beacons produce "chirps" that are clearly audible to the human ear. People who were present when a FR was recovered from deep water often commented that they could hear the beacon. The beacons in both of Air Florida's FR's failed. I never herd why they failed, presumably due to an unusually hard impact. If a lack of maintenance or some other apparently easily correctable problem caused the beacon failure, it would have been all over the news.

Sense the "official" French deep ocean search team will not arrive on sight for several days, other "national assets" (subs) of French, US, British or evan Russian origins might be brought to bare. A sub's passive sonar might be able to hear the beacons from considerable distances perhaps a 100 miles or more. If you doubt this, experimental transmissions have been made from the indian ocean, near Malaysia to Woods Hole, Mass and back using the "deep ocean acoustic channel." If a "national asset" is close enough, the official search team will get a message, look hear, or don't look over there with little other explanation. This may be the real reason the US NTSB as gotten involved when there are few signs that the US manufactured engines or avionics were involved.

The signal saying loss of cabin pressure and electrical failure is quite ominous, indicating a midair break-up of the aircraft. Some people have questioned how anything is transmitted with a power failure. Transmitting this much information could be so fast that the equipments power supplies had not discharged yet. The aircrafts location dictates that the transmission had to be over the aircrafts primary communications systems, either long distance radio or satellite. If the message was limited to just those two failures, I'd suspect that the transmission was radio, with it's limited bandwidth. Normally, when a system transmits this type of cry for help, large amounts of supporting data are sent. For aircraft in flight, what's working is often more important than what is not. The reports I've herd said the transmission stopped abruptly, suggesting that normally more would have been sent.
Member
Registered: May 2009
Posts: 125
"The underwater beacons produce "chirps" that are clearly audible to the human ear. "

Interesting. I've tested these devices many times and on all occasions have had to use an electronic device to listen to the chirps. The very name of this device suggests it is beyond the human hearing range. If the Air Florida aircraft crashed in Florida(?), I'd be more inclined to think that the chirps were insects or frogs :)

Having said that, the beacon has not been submerged in water when I've tested it. Perhaps the water modifies the sound? Or perhaps you need to stick your head underwater to hear it? :P

Rgds.
Q>
Member
Registered: May 2009
Posts: 944
Qavion wrote
Quote
Honeywell is quoted as saying that the "black box" recorders have underwater beacons that can be tracked underwater at a depth of 20,000 feet,


My notes have a different interpretation. The operating depth of the beacon is quoted as being 20,000'. i.e. The locator beacon on the front of the DFDR/CVR is in a metal tube (about 1/8" thickness, I'd estimate). It will probably collapse at depths greater than 20,000'.
My notes also say the transmitting range varies depending on the sea water (1800~3000metres)

The old FDR weighs 30lbs, the new one 18lbs. The old CVR was 24lbs. How much helium would you need to lift this? : )

Rgds.
Q>


====================================

Below is another article, this time with a little more technical info but also lots of speculation by various people. For technically complex stories like this, this newspaper isn't as bad as some, but they were recently sold to a big media conglomerate and have become more sensationalistic and politicized. The USA is losing most of its newspapers to the internet very rapidly.

http://online.wsj.com/article/SB124402430768380893.html#printMode

I thought the discussion about converting airliners to a higher-bandwidth, higher information content cockpit and other data transmission system sounded promising, but since I don't know anything about these issues it's easy to convince me!

Take a look at this excerpt from the article below - I didn't know it was possible to send text messages through the maintenance-data transmission system(s). Or is this capability just speculation, too? It doesn't make sense to me that they would try to signal for help or otherwise communicate via this semi-offline maintenance data collection system in the middle of a major in-flight crisis. I can just see someone typing a text message letter by letter instead of trying to help recover the plane. The message might go something like this (satire of news article intended):

"Is anybody reading this message? Radio doesn't work. Plane is falling apart over Atlantic! We just lost cabin pressure too! We're going down! Is anybody there? HELP!!!"

What can they do, key in short text messages through their normal navigation keyboards? Sounds worse than trying to use a Blackberry or a smartphone. Surely they would instead use a radio if they had time to send text messages?

Is any type of worldwide satellite phone normally available to transoceanic crews?

====================
"Investigators also will scour records to determine if the pilots attempted to send any text messages using the maintenance-data transmission system."
====================
_______________
Best wishes,

Phil Bunch
Member
Registered: Jun 2009
Posts: 20
Location: New York
I know I appear and disappear on the aerowinx forum on occasion, and I apologize for that... :oops: i try to follow the forum whenever I get the chance to.

Anyhow, I just wanted to share the following URL that I stumbled upon an hour ago. It contains an outstanding (in my opinion) meteorological analysis of AF447's flight path:

http://www.weathergraphics.com/tim/af447/

Haven't had the chance to read through it completely yet, but it appears to be very comprehensive!!

-Pesach (KJFK)
Member
Registered: Jun 2009
Posts: 20
I miss-spoke. Air Florida was not the accident I was referring too, the correct name escapes me, They did crash in the Florida swamps, after expired oxygen generators started a cargo hold fire. The searchers were latterly up to their person holes in snakes and alligators. The assets of the airline were sold and became what I think is now AirTran. (I'm terrible with names.)

Low frequency sounds propagate farther in water than higher ones. Why would anyone make the sound harder to detect and fade away quicker by making it to high too hear?

Depending on the design of the transducer the presence of water may greatly effect the operating frequency. Water is 4? orders of magnitude denser that air and the acoustic loading of the transducer will be that much different, potentially shifting the resonance frequency from 100,000 Hz to 10 Hz, from well above human hearing to below. While the actual frequency shift is probably much less, a shift from ultrasonic (above 20k) to the hearing midrange, 2 to 3k in water is quite likely.

If the transducer is capable of wide band operation, testing it at high frequencies may be simply to avoid annoying people not involved with the test. In your environment, ware testing is only occasional, the sound would be of little concern, but in the factory that makes them, the sound could be a real problem. Often details of test procedures used in production persist well after they have any meaning out side of the plant.

Also, I believe the batteries for the pinger are water activated. Water activation removes nearly any possibility of the battery discharging before it is needed. The only limitation on the shelf/service life is moisture absorbed or condensed from the air. Of course condensation can be a serious problem for aircraft. Having the battery water activated simplifies and improves the reliability of the system by removing the need for some kind of switch to turn the thing on.
Member
Registered: May 2009
Posts: 772
Location: Sydney, Australia
Qavion wrote
Quote
sidetrack: Qavion, does the 777 have the same Honeywell ADIRU as the 'bus?


Sorry, John. I currently don't have access to this information. Our own airline doesn't fly 777's and has very limited exposure to foreign and other operators these days. The 777 maintenance manual I have access to doesn't mention manufacturers or p/n's.

Rgds.
Q>


I should have realised your exposure would be limited given the last few years of 'management' :) Thanks anyway.
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« Last edit by John Golin on Thu, 04 Jun 2009 06:19:50 +0000. »
Member
Registered: May 2009
Posts: 772
Location: Sydney, Australia
Dominic Manzer wrote
I miss-spoke. Air Florida was not the accident I was referring too, the correct name escapes me,


I believe it was ValuJet... I think Air Florida was the flight that crashed in the Potomac.
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Member
Registered: Jun 2009
Posts: 20
"I didn't know it was possible to send text messages through the maintenance-data transmission system(s)."

Yes, messages can be sent in both directions. This system was used on 9-11 to attempt to send a clandestine message to all pilots to take precautions. The intent was to alert the pilots without letting the hijackers now about the communication. The message to the plane that went down in Pen' was received before the takeover but was not read. It could have made a difference if it had been read. A plain speech radio message would have worked, but the status of each cockpit was unknowable on the ground and there is no why to broadcast to all planes at once.

As far as other modern communications, the passengers often have far better capability than in the cockpit. As 911 showed, cell phones work when over a ground network. If the plane is equipped with internet or cell phone support the passengers can get better wether information than the pilots.

The trains oceanic air control system is in dire need of updating. It is still done the same way it was in the 1940's, sometimes using equipment that was built for World War II. Manual positions reports, unreliable radio communications, no modern in cockpit wether. All of these have contributed to the uncertainty in this accident.

The cockpit is a difficult place to get new technology into. The FAA is reluctant to approve or mandate anything that will cost airlines money. Airlines do not want to change the cockpit without explicit FAA approval or requirement because of liability concerns. As a result, obvious safety improvements such as GPS have been very slow to get to pilots. I had a close call landing in Halifax when the pilot (the Chief pilot for the airline) found out the airport was well below minimums by landing. The GPS receiver I had with me would have made that landing much safer. I could not see forward, but i think we nearly landed in the bushes to the left of the runway.
Member
Registered: Jun 2009
Posts: 20
John wrote
Dominic Manzer wrote
I miss-spoke. Air Florida was not the accident I was referring too, the correct name escapes me,


I believe it was ValuJet... I think Air Florida was the flight that crashed in the Potomac.


Thanks John, I should not have made that mistake as I happened to be in DC for the first time that terrible day, 26 years ago.
Member
Registered: May 2009
Posts: 125
Further info about text messages.

Our airline has 2 types of message groups:

FLT DISPTCH and MISC MSG's

Text messages of up to 2 pages long can be sent to "Flt Dispatch" for flight ops type of messages. These messages are addressed to one destination only.

The MISCellaneous MESSAGES menu also allows 2 pages of messages to be sent, but a 7 character address must be typed in. Our maintenance control centre has it's own unique address.

Ground stations have the capability of uplifting messages to the aircaft (if it's unique address is known).

Cheers.

Q>
Member
Registered: Jun 2009
Posts: 138
Location: Melton Mowbray. U.K.
So just one other thought (thinking out alond here)

Is there a system where say in addition to storing data on the black box, that there could be a reduced stream of data being transmitted 'somewhere'.

Not sure if transmitting and storing lots of data would be practical?

Carl
Moderator
Registered: May 2009
Posts: 2449
Location: KTMB
There is, they do. It is called ACARS.

Now, truly, it isn't ACARS as that is the transport network used to relay the messages. But most airlines have onboard diagnostic equipment, sometimes part of what in the 744 is called the CMC. Typically at predefined moments and when unexpected things happen, this equipment sends a datagram to home base. Routinely, engine performance data at T/O thrust is being sent to engineering, to add to the statistics and monitoring database and help in selecting engines for overhaul or adjustment.

I once was on the flightdeck of a Lauda Air 777 over Indonesia, chatting with the F/O, and he showed me around the system a bit. On the ND, using the 777 mouse pad, a complete health monitoring centre appeared. As he said: "If one of our engines turns a little rough, the guys in Vienna know it immediately. We as pilots don't know it as it won't break through the "need to know" limits of the EICAS. We won't be able to fix it anyway and it doesn't influence any decision we might make. But in Vienna they know, and technicians will be standing at the gate to fix it."

On top of these airline-specific diagnostic systems, there are reporting systems for estimated arrival time, weather reports (usually winds and temperatures), and automatic dependent surveillance aka ADS-C aka frequent automatic position reports. Well, basically what you see at www.hoppie.nl/acars/system/log.html

It depends on the airline what they have installed, but a modern A330 plus a large carrier makes for a pretty good chance that these money-saving systems were available.

And they received six messages in about four minutes time, complaining about problems. Irregular, but not deadly. Then suddenly the last, aborted message about cabin altitude and electrical failures. And never a word from the pilots, not even one desperate "mayday" call. So what hit them, must have been pretty sudden and pretty heavy.

Portuguese TV broadcasts reports of seven TAP flights that were in the same general area at the same time, and the pilots are pulling their hairs out as they experienced nothing, zilch, zero problems. Either we face an invisible thunderstorm that ripped the plane apart in a few minutes with pilots fighting for control, or the plane was already crippled by something else and then went into a thunderstorm to finish it off, or something.

Wait... we have to wait...

Jeroen
Member
Registered: May 2009
Posts: 944
Yet another theory regarding the loss of the Air France airliner.

http://online.wsj.com/article/SB124411224440184797.html#printMode

This time this news source is quoting Airbus people as being concerned about excessive air speed and perhaps iced up pitot tubes due to electrical failures.

Here's an excerpt:
======================

"The developments in the investigation into the crash of Air France Flight 447 come as Airbus prepares to issue guidance reminding airlines world-wide to follow pre-determined procedures when pilots suspect their airspeed indicators are malfunctioning, according to these officials. The Airbus announcement, expected to be released later Thursday, would be the first specific indication that investigators suspect problems with airspeed indicators could have been the first stage of a cascading series of electrical and mechanical malfunctions aboard the packed Airbus jetliner."

<snip>

"Under this preliminary scenario -- which is still developing and could be altered after further analysis -- airspeed sensors called pitot tubes may have iced up as the plane flew through a ferocious thunderstorm that could have included hail and violent updrafts, these people said. The devices, which have redundant features and are supposed to be heated, are the primary way pilots know how fast their aircraft is flying."

=====================
_______________
Best wishes,

Phil Bunch
Member
Registered: May 2009
Posts: 497
There was a small news items this morning on Dutch radio; it appears that the authorities are now considering it might be a terrorist attack after all. They base this on the very large area in which debris seems to have come down, and large patches of unburned fuel found on the ocean.

let's hope they are able to salvage the FDR and voice recorder soon.

Jeroen
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Location: KTMB
A strong argument against a terrorist attack would be that no organisation has loudly claimed success in the war against whatever.
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Location: between EDDF and EDDN
Jeroen Hoppenbrouwers wrote
A strong argument against a terrorist attack would be that no organisation has loudly claimed success in the war against whatever.


Did somebody claim success after Lockerbie? As far as I rememeber, they said, they would not have known about the bomb on board, if the plane exploded over the sea and all would have sunk.

What still confuses me is, that the debris they found is far south of the last report on the south side of the thunderstorm. The aircraft was northbound and about to leave the storm cell.
http://www.avherald.com/h?article=41a81ef1/0004&opt=0
-> satellite image from 2:45 UTC

Today the german Spiegel http://www.spiegel.de/panorama/0,1518,628677,00.html says, the debries found is not from the missing Air France A 330. They had no wooden pallets on board.

Peter

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