777 down

[gordner]

Subs today cruise at speeds in excess of 20 knots submerged, they could circumnavigate the globe in less than two months, keep in mind the run that cruise 24/7...I imagine there are quite a few subs involved in the search using passive and active sonar in suspect crash areas.

[futuresoptions]

This story has brought back memories of the book I read about the Uss Indianapolis... Great read if you ever get the chance.

[cockerpunk]

Originally Posted by gordner

Subs today cruise at speeds in excess of 20 knots submerged, they could circumnavigate the globe in less than two months, keep in mind the run that cruise 24/7...I imagine there are quite a few subs involved in the search using passive and active sonar in suspect crash areas.

mostly if they were in the area already.

most of the time, a sub will not run full speed, to do so is very loud, and in underwater warfare, noise means death.

in the same vane as not exposing our radar and satellite technology, there would be little purpose in exposing where our subs are, and how they sound to everyone.

[Seahawk]

Originally Posted by ossiblue

I can only speculate on the use of subs. From what I heard from one expert, the deployment of a sub requires a lead time--the implication being, they are deployed on crucial defense missions and to divert would take a planning stage or an extreme emergency. Don't know if the loss of a commercial airliner rises to that emergency level, especially if it's at the bottom of the ocean.

As far as the use of towed arrays, we're back to location. Can you tow arrays across a nearly 3 million square mile area? Can you tow arrays across an area the size of Arizona? Without wreckage and back-tracking to approximate location, the use of arrays (which move at approximately 2 knots) would be a waste of assets.

I chased a lot of subs around doing anti-submarine warfare, so, while not an expert, I have studied acoustics quite a bit.

Sound propagation in water, distance the sound will travel, is affected by temperature, salinity, depth, frequency of the emitter, the sensitivity of the search sensor, the placement of the search sensor and the ambient noise around the emitter (think ship traffic).

Pretty basic stuff, but then add the thermoclines, deep sound channels, convergence zones etc. is gets complicated.

The best platform for detecting sound in water is a submarine, because it lives underwater and has a very quiet signature and can tow passive arrays.

The next are surface ships with towed arrays. The next two, SOSUS and sonobuoys are limited in range.

Suffice it to say that medium detection ranges (MDR is calculated using all the stuff I just typed and much more and measure the predicted range that sound can be detected by a passive listening device) varies dramatically in different water conditions (some oceans have "dirty water" that inhibits sound travel) and where the emitter and sensor are in relation to each other.

For instance, in certain conditions, an abrupt thermocline can effectively prevent sound propagation above a certain water depth...a ship with a towed array that is above the therocline could sail right over the emitter and never hear it: the array would have to be below the TC to pick it up.

MDR's can range from thousand of yards to miles. So you see the problem: Unless the area of probability of is fairly well known, mowing the ocean with subs and ships is problematic.

On the active sonar side, we used predicted detection ranges (PDR). PDR's are usually much less than MDR's and, frankly, would be useless searching for the planes emitter or wreckage. You guys are thinking about side scanning sonar, which needs, again, a known search probability area to be other than an interesting exercise in futility.

I may have missed a few concepts (and there are a few sub guys that post here) but those are the basics.

As I said before, open ocean search, above or below, is a cruel task.

[futuresoptions]

Planes should have a large dye pack installed just in case they go for a swim.

[gordner]

a dye pack large enough to make a difference would probably weigh enough to remove 25% of the passengers. Would you pay 25% more per seat to know that they will find your dead body after a crash? Most people will not pay a cent extra for safety.

[futuresoptions]

Originally Posted by gordner

a dye pack large enough to make a difference would probably weigh enough to remove 25% of the passengers. Would you pay 25% more per seat to know that they will find your dead body after a crash? Most people will not pay a cent extra for safety.

Good observation... maybe they could incorporate it into the fuel sorta like they do the red dye for farmers diesel... Just a thought

[widebody911]

[GWN7]

The US Navy used SOSUS (and later IUSS) to find the Thresher and K-129. You would figure that a 777 hitting the water in the middle of the night might make enough noise to be heard by them?

[cockerpunk]

Originally Posted by GWN7

The US Navy used SOSUS (and later IUSS) to find the Thresher and K-129. You would figure that a 777 hitting the water in the middle of the night might make enough noise to be heard by them?

SOSUS is mostly in the Atlantic and off the west coast of the continental USA in the Pacific. it was mostly designed to be an early warning/picket line for USSR missile subs. probably not much in the indian ocean

also, the software filtration on systems like these are designed to filter out sudden transient noises because it turns out the ocean is full of them. you better beleive that micro-earthquakes, oil exploration expositions etc etc are much louder, and transmit far better then a surface strike of an aircraft. also, noises on surface tend to be filtered out rapidly and do not transmit nearly as well as sounds produced very deep.

[Aurel]

Did you guys see the plane had a load of Li-ion cells in cargo? I could have caused a fire, although I sure hope it did not...

Malaysiakini

[GWN7]

K-129 went boom over 1,500 miles from Hawaii. SOSUS type systems are in the Mediterranean Sea, Norwegian Sea, the Middle East (Indian Ocean), just about anywhere there is water. Even in waters down to -18,000 ft. Russian subs were using deep water canyons to evade the shallower systems so the Navy built systems to track them.

The Naval Institute Guide to World Naval Weapons Systems, 1997-1998 - Norman Friedman - Google Books

While a plane as large as a 777 might not record well being surface noise when it splashed it would make a bunch of noise as it sunk and parts imploded which should stand out as a abnormality to a tracking array.

[GWN7]

Here's another mention of the Indian Ocean: "On the continental shelf areas bordering the North Atlantic was the CAESAR network. In the North Pacific there was COLOSSUS plus a few sensors in the Indian Ocean and a few other places that no one will talk about. "

https://www.strategypage.com/dls/articles/South-Koreas-Secret-SOSUS-System-2-5-2011.asp

[GWN7]

Here's one that mentions Diego Garcia and a "facility in the Northeastern part of the Indian Ocean"

Bases Abroad: The Global Foreign Military Presence - Robert E. Harkavy - Google Books

[kiwiokie]

Originally Posted by Aurel

Did you guys see the plane had a load of Li-ion cells in cargo? I could have caused a fire, although I sure hope it did not...

Malaysiakini

That is an interesting development. This story is anything but predictable.

[porwolf]

Originally Posted by Aurel

Did you guys see the plane had a load of Li-ion cells in cargo? I could have caused a fire, although I sure hope it did not...

Malaysiakini

Taking a load of Lithium Batteries fro Maylasia to China? That is like taking coals to Newcastle! Maybe tose lithium batteries were faulty returns to the factory?

[porwolf]

Originally Posted by porwolf

Taking a load of Lithium Batteries fro Maylasia to China? That is like taking coals to Newcastle! Maybe tose lithium batteries were faulty returns to the factory?

Never mind. My post was premature. Maylasia does produce lithium batteries:

http://www.theedgemalaysia.com/in-the-edge-financial-daily-today/274256-msia-to-set-up-aseans-first-lithium-ion-battery-plant-for-vehicles.html

[porwolf]

Some lessons learned already from MH370?

5 things MH370 has taught us about aviation - Opinion - The Boston Globe

[M.D. Holloway]

or the splash would have set off the bouys that are used for rouge wave detection...

[Nate2046]

Originally Posted by porwolf

Some lessons learned already from MH370?

5 things MH370 has taught us about aviation - Opinion - The Boston Globe

Which quotes from this;
A Startlingly Simple Theory About the Missing Malaysia Airlines Jet | Autopia | Wired.com

I've seen links to this article all over the internet, can we please just put it to rest?

For me, the loss of transponders and communications makes perfect sense in a fire. And there most likely was an electrical fire. In the case of a fire, the first response is to pull the main busses and restore circuits one by one until you have isolated the bad one. If they pulled the busses, the plane would go silent. It probably was a serious event and the flight crew was occupied with controlling the plane and trying to fight the fire. Aviate, navigate, and lastly, communicate is the mantra in such situations.

No. The first step in any smoke in the cockpit situation is to don the o2 masks and establish communications. The pilot flying would continue to fly the airplane and take over radio duties while the pilot monitoring ran the appropriate checklist. You don't just start pulling breakers to isolate busses. If a turn was made, it would be initiated by that pilot flying and he would certainly make that known to ATC. You'll find that most pilots are very reluctant to initiate a turn off course without communicating it to ATC.

Can you name a major fire resulting in the loss of the aircraft where the pilot didn't have a chance to make a distress call? I can't.