Report on USS Greeneville - Ehime Maru collision

[Bill Nichols]

The NTSB has released its report on the USS Greeneville - Ehime Maru collision. I strongly recommend reading it, as it gives an excellent description of what goes on aboard a US nuclear sub while underway.

Link here:

http://www.ntsb.gov/publictn/2005/MAB0501.htm

[Kapitan]

a good read long but good

[Molon Labe]

Required reading for the aTMA programmers at SCS!

No good solution going in a straight line!
No good solution on too little data per leg!

Just think how many people would still be alive if they had our autocrew....

[Bellman]

:sunny: Thanks Bill - have just dld the pdf.

Read the 'unofficial repot' extracts back in August abd it will be very interesting to see the 'final'.

[FERdeBOER]

Great, Bill, very interesting. :up: :up:

[TopTorp '92]

The NTSB has released its report on the USS Greeneville - Ehime Maru collision. I strongly recommend reading it, as it gives an excellent description of what goes on aboard a US nuclear sub while underway.

Link here:

http://www.ntsb.gov/publictn/2005/MAB0501.htm

Great link Bill. Very informative.

[N00be]

15 As is typical of all submarines, interference from noises generated by the Greeneville itself prevented the sonar system from reliably detecting sonar signals between approximately 120° and 240° relative to the vessel's bow. This arc astern of the vessel is known as the "baffles" area, and a submarine has to periodically alter course to uncover this null area, or "clear the baffles," for the sonar system.


Is this simulated in DW as well? Or is the baffle area the black area on the broadband?

[Skorn]

Good read, lots of information in there. Don't remember that happening over 4 years ago. Man, time flies...

[LuftWolf]

Is this simulated in DW as well? Or is the baffle area the black area on the broadband?

The baffled area is the black part on the sonar display.

[N00be]

But I dont understand. The black area is so small. The baffles are supposed to be 120 degree wide.
As far as I understand it, there is the black area, thats directly behind your sub (sonar blocked) and there are the baffles between 120 and 240 where signals are not blocked, but interfere with your own subs noises, therefore are not reliable or not shown at all). But Im prolly wrong here, or?

[LuftWolf]

The way baffles are modelled in DW is not at all realistic.

The baffles are WAY too small.

Incidentially, this is corrected in the next version of the LWAMI Mod, 2.02, which will be released today or tomorrow morning. :yep: :)

[Bellman]

:lol: Amen. :up:

[N00be]

In the report they talk about the bearing rate as an indicator whether its a closing or opening contact.

He said that, as sonar supervisor, he looked for "something with a very high bearing rate, something that may be on our left side drawing right, or right side drawing left," which could represent a "closing" situation (meaning the target is heading toward the submarine). He said that when sonar first gained S-12 and S-13 (the Ehime Maru), "they did not have much of a bearing rate."


Where do I get that info in DW when I have a tracker assigned to a contact?

[LuftWolf]

Once you have a solution in TMA, it is listed in the contact information window on the Nav Map.

[N00be]

First, thanx for the quick reply. :) I was looking for a bearing rate before TMA has been done, cause after all thats (bearing) all I have for the first 2 minutes, and even after that I prolly wont do a TMA with just 2 or 3 bearing rates, so a bearingrate indicator without having to have a solution would be really cool. But I guess there is none...? :-?

[Molon Labe]

You can just look at the sonar display. If the contact is changing bearing quickly, it has a high bearing rate. If it stays in place, its a low bearing rate. ;)

PS, you're not going to learn too much in less time than it takes to do TMA. TMA is essentially the analysis of the bearing rate data.

[LuftWolf]

Well, you can see on your sonar display how quickly the bearing to the contact changes.

If your line on the waterfall is very slanted, then you can quess that the target is close and moving reasonably fast. If your line is very straight, then you can guess that the contact is farther away. This doesn't always work (for example, the target is heading straight towards you or away from you), but generally speaking, a faster bearing change means that the target is closer, and slower bearing change means the target is farther away.

It's a matter of putting all your experience and information together to generate situational awareness. The more experience you have in general and information in any specific situation, the better your situational awareness will be. :)

[Molon Labe]

Well, you can see on your sonar display how quickly the bearing to the contact changes.

If your line on the waterfall is very slanted, then you can quess that the target is close and moving reasonably fast. If your line is very straight, then you can guess that the contact is farther away. This doesn't always work (for example, the target is heading straight towards you or away from you), but generally speaking, a faster bearing change means that the target is closer, and slower bearing change means the target is farther away.

And a contact that you know is close with very little bearing change means, "LOOK THE FRACK OUT!"

[LuftWolf]

:rotfl:

LOL, yeah. :lol:

I'm thinking... torpedoes! ;)

[Molon Labe]

:rotfl:

LOL, yeah. :lol:

I'm thinking... torpedoes! ;)

Well, you should know if a torpedo is headed for you or not pretty quickly; since they move so quickly, even a distant torpedo will produce a visible bearing rate in a few minutes if it is not headed on an intercept course with you.

"Not-so-distant" torpedoes you can just assume have your name on them, in fact I tend to pucker up quite a bit from a torp with a very high bearing rate, because I know that it's so close I probably don't have time to turn to use the CM's properly.