Quote:
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.
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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.