Q Admiral, what I would like to do now goes take you to each one of the afternoon events in more detail.
You mentioned that the first evolution that she performed was angles and dangles. And I believe your testimony was that began at 13:16?
A Yes, and the times in here are to the nearest minute.
We actually conducted about a 45 second correction in the times that was subsequent to my report but in preparation of this chart, after a more detailed comparison of the digital recorded data was done after I signed my report, but these are to the nearest minute. And at 13:16, which is where my laser pointer is here, when the ship was on a course north, she increases speed to 14 knots, about a standard bell, and commences angles.
And in doing these angles, she cycled between increasing up and down angles of up to 30 degrees, up and down, and increasing and decreasing depth in a band between 160 and 650 feet.
And these are logical and safe boundaries to this condition, to demonstrate the maneuverability of ships in changing depth rapidly.
Q So you are talking about movement in the vertical axis and the vertical part of the water column?
A That is correct. I am talking about movement such as an airplane would climb to a higher altitude, and you would rotate back, and you would feel it going from horizontal up to a 30 degree up angle. Well, the submarine would actually take this 30 degree up angle, so you would have people holding on to equipment because their floor would be angled at 30 degrees, and they would otherwise slide along it.
And similarly when they would want to go deeper, they would go through horizontal, to go deeper in a hurry, and again, they would hold on because their floor has gone this 30 degree down-slope.
Q In your investigation, did you assess how the ship performed angles and dangles?
A Yes, I did. From what I could tell, they did an excellent professional job.
This is a fairly challenging evolution, especially in a case of a ship that had not operated for a long time at sea. The Greenville had been in maintenance for two months prior, and so they had not a lot of seatime prior to this event, and their ship’s control party demonstrated significant proficiency.
It was a very professional job.
Q Admiral, can you explain to the members the
difference between ship’s depth and keel depth that
you referred to earlier?
A Well, of course, when the ship is on a zero angle, very horizontal, they’re synonymous. You may have indicators on the ship like the digital depth detector system or the mechanical depth dector systems that would indicate without an error what the depth is, but the true depth is the keel depth, and all the indicators should be closely in agreement with that when the ship is on an angle.
And that would be a keel on a black calm sea. When you are doing an up-and-down angle, your digital depth dectector, in the center forward line of the ship has depth sensing ports there aren’t necessarily the lowest part of the ship or the highest part of the ship. Your rudder on a up-angle would be the lowest part, and your bow on a down-angle would be the lowest part.
So that depth is just an average depth, not a true depth when you are at a angle. Does that answer the question?
A Yes, sir.
Q At what time did Greenville stop angles and dangles?
A She completed her angles and dangles at 13:25 local.
Q You indicated on the chart that she increased speed to some speed in excess of 20 knots. What was she doing at that time?
A She was transitioning to a different type of maneuver, a maneuver of a horizontal plane where she would turn left and right to demonstrate how maneuverable these ships are, when you want to turn them in a hurry tactically.
So she would bring up her bell up to speeds up to flank and use up to full rudder, which is 30 degrees left to right, to turn very quickly left to right.
And that commenced at 13:25, and persisted until about six minutes until 13:31, as indicated on this chart at that time mark.
I might add, it’s not a simple evolution on a submarine with this much power, and the hydrodynamics
of an attack submarine. It’s difficult to maintain a
zero angle in a zero depth change while going through these horizontal turns if you are not reading the problem and anticipating the effects of angle and depth change, the ships control party can quickly find that the ship is at a large angle and changing depth rapidly, when all you wanted to had to do was change course rapidly.
So once again, if I may just comment, the ship demonstrated significant proficiency, a very professional job of doing the ship’s maneuvers without changing angle or depth appreciably, and did it in a very seaman-like manner.
Q Sir, what was the next evolution that Greenville performed?
A The next evolution were preparations to do the emergency blow.
Q And sir, what are the subsets of preparing to do a emergency blow or an emergency surface?
A The basically steps to doing an emergency blow from a submerged condition when you are doing it in a controlled manner, and of course, it’s important to remark that this emergency blow system is primarily an emergency system designed to very quickly get the ship to surface in the event of a severe casualty, such as flooding.
But when you demonstrate its use or when you test its use, you go through a more controlled process of first going to periscope depth, and verifying that the area is clear of surface contacts who would be endangered, and would also endanger our ship if you should surface under them.
And then you go back fairly quickly to a depth you want to conduct the blow from, probably 400 feet is our normal practice, because that is deep enough to allow the system to work, but shallow enough to not have to use excessive amounts of air.
And then you conduct the emergency blow fairly expeditiously, so that that previously verified surface clear picture has not had time to degrade.
Q So you are describing four steps to the process — preparing to go to periscope depth, then going to periscope depth, and then a emergency deep, and then the emergency surface; is that correct?
A Let me make one slight correction. The preparing to go to periscope depth part, I
agree with. Going and operating in periscope depth, I agree with. The emergency deep — that is another training evolution to quickly go below periscope depth if you happen to see a contact while you are at periscope depth.
So she demonstrated that to go deep, but you could also go down in a routine fashion, and then once you are deep, conduct the emergency blow as a fourth step.
Q Let’s focus on Greenville as she prepared to go to periscope depth. What steps does the ship take as it prepares to go to periscope depth?
A Well, I think you need to look at the context that the Greenville was transitioning from to do that evolution.
She was operating fast, making a number of turns. She was relatively deep at 400 feet, when she was completing this red portion of her track at high speed turns.
So the first thing she would want to do would be to go shallow, below a depth where she would collide with a surface vessel, but shallow enough to have success in the ocean.
And in this case, it is 150 feet.
Q And that’s because the sonar at the 150 feet is going to be able to pick up the sound signatures of vessels better?
A Yes. In general, because of the nature of the sound column and the environment, that tends to create the least obstacles on the sound ray path for you to hear that surface noise.
So going to that shallower depth of 150 feet and also slowing to 10 knots or less, which is a good compromise speed to put enough speed through the water so you could change bearings to contacts and develop good fire control solutions, but not be so fast as to create excessive machinery and especially flow noise around your own sonar.
For example, when you go over 20 knots, your sonar is basically deaf, and you have to slow down to hear very well.
So she was coming shallower and slowing down in order to conduct the preparations to go to periscope depth through Target Motion Analysis with sonar.
Q Sir, generally, is there any time limit associated wiwth going to periscope depth? Does it take a certain amount of time to prepare to do that?
A Well, this is one of those questions that has to be answered by quotes “it depends” as a preliminary to any answer.
Because the environment, the number of contacts, what the ship had been previously doing, its previous understanding of the local contact picture before it starts to do this — all of that is pertinent.
I think in a general sense, it takes at least two good sonar rays, with one or two contacts in the same sector, and you have to increase those legs as you gain more sectors around the 360 azimuth of the submarine, as I will describe in a minute, in order to fully understand not only which contacts are there but more pertinently are any of them close in range.
Q You mentioned earlier —
A So let me just see if I can’t finish my answer.
I would say, nominally, ten minutes or more, because you want to have three to five minutes per leg, and if you don’t have many contacts and they are in the same general area, two legs may suffice to determine none of them are close. So I would say as a minimum ten minutes.
Q Okay, in your preliminary investigation, were any time limits placed on Greenville coming to periscope depth?
A Well, here is the thing. I have a statement coming from I believe the officer of the deck who was interviewed by Commodore Bias that indicated the captain indicated he wanted to be at periscope depth in five minutes. And that was as articulated at a time when they had just commenced their transition from the high speed operations to come shallow, clear baffles, and go to periscope depth. So the statement by the commanding officer would imply that he would want to get to periscope depth in a hurry.
And I can surmise it was because they were like per their previous schedule.
Q Did you confirm that statement from the OD from any other sources?
A So, the statement by the Commanding Officer would imply that he wanted to get to periscope depth in a hurry. And I can surmise it was because they were late per their previous schedule.
Q Did you confirm that statement from the OOD through any other sources?
A Well, I know on a time line they did in fact almost achieve that goal of five minutes. I believe it was six minutes until they got to periscope depth, but when they commenced preparations to do so. So, factually they near achieved that short amount — that aggressive goal, but I have no other statements that pertain — correction — no, I have no other statements that directly pertain to that.
Q Okay, sir. Sir, you mentioned two good legs, and you also mentioned a concept or term TMA, I assume they’re associated. What is TMA?
A TMA stands for target motion analysis, and it is a method that submarines use to use passive sonar bearings to determine the parameters, particularly course speed and range of contacts, submarine and surface contacts in relation to ownership.
And it’s a process that considerable body of experience and technical development has been devoted to in the last 50 years.
Q And, sir, why is TMA so important when you’re coming to periscope depth?
A Well, in this scenario where safety of ship is your primary consideration. TMA is fund mentally important to ensure you’re not so close to a surface contact that there will be a danger of collision when you come to periscope depth at first sea realm, or come under underneath them. Coming to periscope depth is inherently dangerous because until you’ve had the additional sensors above the water line, such as visual sensors through the periscope, electronic sensors, you have only your sonar to have determined whether or not there are contacts present. And sonar alone is not — does not give you complete assurance that there are no surface contacts there.
For example, if you have a sailboat and a fiberglass hull who has no machinery operating, that boat may be creating zero acoustic energy that your sonar would ever hear. You may have a metal ship that does have machinery but has chosen for that moment not to operate it for whatever reason and is drifting, fishing, or whatever.
So, there are scenarios where you could have a large ship, say a merchant ship with certain aspects such as bow on to you where their hull effectively is an echo chamber that captures her machinery noise and doesn’t let it transmit through the water to your sonar.
So there are a number of scenarios where sonar doesn’t completely cover your number for fully understanding the surface picture, and for that reason, since that’s all you have until you’re above that surface layer with your periscope, that’s a period of risk to approach that periscope depth depth.
Q Sir, you mentioned that you need two good legs to conduct TMA. Would you define what a good leg means, what you mean by that?
A Yes. First of all it’s another depends type of answer, because there are a lot of variables that affect the ability of a ship to determine a target’s parameters.
The environment greatly determines that, the operations of the other target greatly determine that, but in general if you have an environment and a target ship that’s providing the good, steady, reliable signal so that your fire control and your sonar system have good information to develop from, and to analyze, it would take in general two legs of three to five minutes per leg with our digital fire control system and our digital sonar system to determine a pretty good picture of what that ship is doing. And that’s bare minimum, because a single leg solution would not resolve a lot of ambiguity of what that other ship is doing.
So, in summary, the two good legs would allow you to use passive sonar, and your systems on board, to as a minimum determine that the contact is not very close. And probably much more information of value.
Now, I think you need to lead me on in the questioning to a point of understanding baffled areas and how you have to reorient the ship not only to resolve a single contact but also look for other contacts.
Q And that’s why you take — you go to a second leg in order to clear the baffles?
A Yes. Sonar baffles are about a hundred — on this class of submarine was honard sonars about 120 degrees in the stern sector centered either side of the stern of the ship relative, where you’re acoustically deafened because the sonar is not designed to look in that sector through ownership’s machinery and hull noise. So you turn your ship in the horizontal plane to uncover your previously baffled area and you generally turn at least 120 degrees so you now have that previously deafened sector under observation by your passive sonar system. And you may have new contacts in that sector, and if so you start to develop your first leg on this new course of information on those new contacts.
Meanwhile, this turn has allowed you to develop a second leg on previously detected contacts, which is allowing you to refine their perimeters.
Q So that’s generally, sir, you’ve described how a ship would normally do or what the standard TMA good solution would require, two good legs.
VADM. NATHMAN: Let’s take a recess here.
CAPT MACDONALD: Yes, sir.
VADM. NATHMAN: Court will be in recess for approximately 20 minutes.
BY MR. MACDONALD:
Q Admiral Griffiths, what I’d like to do is first of all remind you that you’re still under oath.
Just a couple of questions and kind of back to up a little bit. You mentioned that it was out of commission in the control room, as to simply a repeater, correct? It — the sonar information, the raw data that comes in on the busy one is simply repeated up here for the Officer of the Deck to look at, correct?
A Yes, that’s correct. However, I think we should recognize that the vantage point is different in control than it is in sonar. The Officer of the Deck as the advantage of having a more complete situational awareness of the ship and its location in respect to other contacts and how it’s been driven in the past and how he’s going to drive it in the future in order to optimize an understanding of the context.
So, although they’re looking at the same data, they are looking through a much different filter, and I would say in the Officer of the Deck’s case he’s looking through a much more complete tactical filter than the sonar operator is.
So, although it is the same data, his perspective in viewing that data is much more important, I think, than that of an individual sonar man.
Q Sir, can a submarine use active sonar when it comes to — as it prepares to come to periscope depth as yet another sensor that it could use to detect surface contact?
A Yes, it could. Active sonar would certainly be another sensor that the ship could elect to use. There are two basic active sonar systems on the Greeneville that would pertain here, the first is a middle frequency or MF sonar that’s part of the mainframe, and the sphere, and this sonar system which is a lower frequency than the other alternative I’ll describe in a minute is a more powerful sonar that has a theoretically a longer range and would provide some utility in understanding the exact range targets, if it would get a return that could be reliable.
And then the second of the two active sonar systems that the Greeneville has is the high frequency sonar. This sonar is generally intended for close contacts under ice avoidance in mine detection, floating mine detection.
So it’s a higher resolution, higher frequency sonar for closer contacts, and both have some utility in searching for surface vessels as well as submarines.
However, I think I should say that their general utility for routinely going to periscope depth is not very good.
Q Why do you say that, sir?
A I say that, and I’ll have to take you through some of the limitations of active sonar to fully elaborate my answer.
There are costs as well as benefits to use of active sonar on a submarine such as the Greeneville. The first thing to mention is, just as for passive sonar, active sonar is very dependent on the vagres of the environment, and when you use active sonar, the first thing you have to try to do is understand the environment and then optimize preselected parameters of your active sonar to make use of that understanding of the environment.
Understanding the environment is a very challenging task on a submarine. It varies temporally and it varies spacially at a fairly great rate, and in order to pre select these parameters in your active sonar, and do it correctly so that it optimizes that environment is a very challenging task.
Realistically what you would see a submarine do to employ active sonar is to do some inset to measurements that actually use the active sonar in varying parameters, and then determine what seems to give it the best result, kind of just pre-tuning with active sonar would then give you more confidential that it would be useful in that specific environment you’re operating in. So that’s one particular limitation.
If you’re about to go, for example, to periscope depth and you want to use active sonar for the first time in quite a while to determine if it’s safe, you have to kind of go through a laboratory period where you use it and then tune it so that you know it’s going to at least provide theoretically useful data, and that’s the first drawback.
The second drawback is that the very nature of active sonar is that it provides a great deal of false positive returns.
Q What do you mean by false positive returns, sir?
A A false positive would be an indication on the screen that you have a contact when you really do not. Biologics, the physics of acoustics under water that cause reverberations and returns when there are no solid objects there, rate tracing through the water column, interruption with the surface pictures, waves and swells, distortion caused by the bottom, all of these factors, boundary conditions and in the water column can cause a number of positive returns that are false. And the challenge here is to try to separate the weak from the chaff before you make tactical decisions on going towards the surface to periscope depth.
Given an infinite amount of time this may prove eventually to be useful, but generally to get to periscope depth in a reasonable amount of time you don’t have time to separate that weak from the chaff.
There’s a third draw back that’s significant, and this is in a piece time local operations environment completely discounting detection by the enemy in a mission, which is not even a factor here. And that third drawback is that you are not able to listen with your passive sonar effectively, while you’re using your active sonar. Both the oral response that the human operator will have, and the visual displays of the sonar system are interrupted by these active transmissions from on ship.
Q So you’re actually degrading the ability of your passive sonar to pick up surface contact?
So, you are doing the active sonar at the cost of an effective passive sonar if you’re using active sonar. Now, there are periods where active sonar has use. I’m not trying to raise a question of why these submarines even have active sonar, I’m just suggesting that preparing to go to periscope depth is not an occasion where they are very useful.
Q Sir, in your experience, your long experience as a submarine officer, what’s the best system that a submarine has? What’s the best sensor that it has to — as it prepares to come to periscope depth?
A Well, without a doubt it’s the passive sonar suite, the mainframe passive sonar suite in the Greeneville’s case the busy one sonar in this sphere is the best system they have. And over the long haul is — orders of magnitude more effective than any other sonar suite to prepare the ship safely to go up.
Q Including active sonar, sir?
A Including active sonar.
Q What I’d like to do now, I know before the break we were talking about what constitutes good TMA and we were talking in generalities not the specifics of Greeneville.
What I’d like to do now is kind of focus in on USS Greeneville and how she performed target motion analysis on the afternoon of 9 February.
Do you know, sir, in your investigation whether Greeneville held sonar contact on the Ehime-Maru while she prepared to go to periscope depth?
A Yes, she did hold contact on Ehime-Maru intermittently, between about 12:32 at the bottom of the chart right here, and the time of the collision at 1343. And I say intermittently because there were periods when she did not hold contact on Ehime-Maru.
Q Sir, did she assign Ehime-Maru a sonar contact number?
A Yes. She assigned Ehime-Maru Sierra 13, or S 13.
Q Sir, what does the S stand for?
A The S stands for sonar, and is an arbitrary system of labeling sonar contacts on submarines, in contrast to, for example, if they saw a contact visually through the periscope they would assign it a visual number, or Victor and a number, or if they had it on ESM they would assign it an echo number or E number, and so forth. So in this case sonar contact and the number 13 is an arbitrary, the next number available for the next contact after they tracked a different contact Sierra 12. So Sierra 13 in hindsight is Ehime-Maru.
Q Sir, it’s your testimony that at least, from as early as time 1230 the Greeneville held Ehime-Maru as a sonar contact?
A That’s correct.
Q Commander Harrison, would you mark the next chart as Court Exhibit 7. Would you show it to Admiral Griffiths, please?
Admiral, what’s depicted on the left hand side of the chart that Commander Harrison is showing you?
A This side, the left hand side of this chart shows bearing along the bottom at true degrees, and time increasing along the side so that 1340 is here, a little over an hour earlier 1230 is at the bottom working up in time here. So this is the Sierra 13 bearings recorded by the sonar recording system in the fire control portion of Greeneville, digital recording system, bearing versus time.
Q Sir, that’s actually a blow-up of a graph that was taken from Greeneville on the 9th?
A Yes. This information is recorded automatically on ships of the class, fire control and sonar suite that the USS Greeneville has which is called advanced rapid COG (phonetic) insertion phase two, which is a varigation of the legacy sonar suite busy one that Greeneville has.
And what is — what occurs is it automatically on a daily basis records digitally this information on all the sonar contacts, as well as the ship’s fire control solutions on those contacts and their fire control system and their ownership’s parameters.
Q Sir, if I could stop you for a minute.
Commander Harrison could you take down these two view graphs and I’d like you to put that one up.
A Now, there’s really two kinds of information did displayed on that left-hand portion of this chart. The dots, the black dots that work their way up the page are discreet sonar bearings to Sierra 13 over time.
Q Admiral, can I stop you just for a minute.Commander Harrison, could you turn the lights up, please?
And sir, before you start explaining the left-hand chart I have another chart that we’d like to have marked and put up. I’d like to have this marked as Court Exhibit 8.
And sir, do you recognize the information data on this chart?
A Yes, I do.
Q And what is it, sir?
A This is an expanded blown-up version of the upper fraction of the left-hand time bearing history for Sierra 13, and additionally it’s two line of sight diagrams that describe it’s orientation of Greeneville on the Ehime-Maru that we’ve constructed in hindsight in looking at the data that correlate horizontally to where the bearings are, so the bottom of the two stick diagrams would correlate to the slanted to the right bearings between a time of 1332 and 1335, and then the upper stick diagram would correspond to the upper fraction of those dots which correspond to times after 1335.
Q Commander Harrison, would you please put that up as well?
Admiral Griffiths, what I’d like for you to do is first speak to the USS Greeneville S 13 versus free construction the left hand side chart, and I’d like you to correlate the black dots with what’s happening here on Greeneville’s track as she’s proceeding towards the collision with the Ehime-Maru.
A All right.
First of all, the time scale of this chart corresponds to the time scale of this chart between 1230 and the collision, so here’s 1230 and here is the collision at the top of this time bearing history. So this represents this whole track data of bearings from the Greeneville as it works its way up this track to the Ehime-Maru as its working its way down this track.
So, just for example, at 1300 here is Ehime-Maru, and here is the Greeneville and that looks like about a bearing of north from or 000 true from the Greeneville to the Ehime-Maru, so if we look at where 1300 is here we can see that it’s approximately 000 or north as the bearing that you readout here.
And a similar correlation could apply at any point on this line and on this track of the two vessels.
Q Admiral, what accounts for the lost contact, lost sonar contact during this period of time here?
A Well, before I answer that, let me just say that if you can see it well enough there is a solid red line that works its way, has some squiggles here in the green shaded area, but generally conforms to the bearing dots when they appear on this chart. That solid line is a continuum, a continuous correlation from the two tracts to Greeneville to Ehime-Maru of bearings, so if you were to draw an infinite number of bearing lines from the Greeneville to the Ehime-Maru correlating a time on the two tracks you would end up with that red line. So that red line is really the law of physics as the two ships approach each other as opposed to sensor data.
The sensor data is comprised of these black dots that superimpose along that line. You’ll notice interestingly that here in the green shaded area the sensor data greatly diverges and falls off what we know to have been the correlation and the bearing of these two ships on these tracks. That’s during the high speed period when it losses its signal because of high frequency noise on the bow of the ship, it’s receiving in the processors to degrade to where it’s no longer reliable, so it falls off track and in general is not reliable there.
These periods where there’s no data has — as compared to consistent data to our reconstruction, or inconsistent data from our reconstruction, no data is generally caused by the course of the Greeneville being such that the acoustic baffles near the stern of the ship is in the direction of Ehime-Maru.
So, that’s the period where the Greeneville can’t acoustically hear the Greeneville — that is the Ehime-Maru because it’s in the baffled area of the submarine.
Q Sir, is any other information you want to tell the Court members of the time bearing chart on the left here?
A You mean in the example — before we get to the expand —
Q The expanded time versus the bearing chart?
A Not at this time.
Q Sir, let’s move over to the expanded time versus bearing chart.
Sir, is this the portion of USS Greeneville’s track where she was conducting target motion analysis?
A Yes. Yes.
Q Sir, could you take the Court members through your description of how she conducted TMA on the afternoon of 9 February?
A Certainly will.
The Greeneville is completing its high speed turns at 400 feet depth when this red terminate here on the track, and you can see it turns — the Greeneville turns to the left to a north early course 340, and that’s this leg right here, she’s going up this leg.
Here on this time bearing she can see she orders the course change to 340, she’s also changing depth and coming up to 150 feet from 400 feet and she’s slowing from her higher speeds in excess of 20 knots down towards 10 knots to do the sonar search. So we have these three dimensional changes occurring in the ship, slowing up angle to change depth to a shallower depth, turning left, come to 340. And that completes here just after 1332.
So, in this phrase — phase right here she begins a short leg to the 340 leg, and I think it’s important at this point to note that in this laboratory stillness of the post mortum, I was able to look at this data focusing only on Sierra 13 and not having just come through the maneuvers on the ship. My high bearing radio (inaudible)… Right, a right 6 degrees bearing rate for the passive sonar information on Ehime-Maru and Sierra 13.
And in my — the stillness of my office space I was able to look at this data and say this tells me there’s a potentially close contact, how did the ship react to that. But I think you need to apply this in context. First of all, you have just completed a very dynamic period of high speed maneuvers, and your history of sonar displays for the last many minutes is one of spaghetti noodles moving all over. Not a reliable display to make valued judgments of context. And the ship knows that. The skipper knows that, the OOD, the sonar men know that during these high speed maneuvers we do not have a stable platform getting reliable sonar information.
And the displays take a while the way our sonar displays work, it takes a number of minutes for them to generate data displayed as consistent new information that is now reliable to make judgments on. And it’s my assessment that this high bearing rate information here, for whatever reason, was not recognized as such by the ship. The ship as a whole, including its components players, because it was too close to the completion of the dynamic phase they had just completed, and the displays really don’t distinguish that as different from the high gyration period.
So, there’s some masking of the impact of interpreting this information because of the transition that was very rapid from dynamic maneuvers to now let’s get stable and take a look at our sonar picture.
Q Sir, you said that it wasn’t recognized by the component players on Greeneville that should have. Could you tell us who should have seen this in terms of the watch stations that —
MR. FILBERT: I would object, I don’t believe that he said they should have seen, he said think didn’t see it. I think this is a statement of his testimony and I’d like the question rephrased.
BY CAPT. MACDONALD:
Q What watch standards would have had access to this data?
A The primary watch standards would have been the sonar operators and the fire control technician of the watch, the sonar and fire control system operators.
The third set of actors would be the Officer of the Deck and others like him if the as do was working on the CON, which it was not. So the Officer of the Deck would not have had a chance to provide his value added to analyzing this displays in this case with Greeneville because the display was broken.
So our primary operators to rely on here are the sonar people and the fire control technicians.
VADM NATHMAN: Admiral, no one asked this question. Make sure we don’t miss this one. If the Officer of the Deck knew his display was not working, he obviously knew that, did he take the opportunities to make sure he could get that same information by going into sonar.
THE WITNESS: Yes, and to some degree he can get the processed information by the fire control system which is in control and he can walk over and look at that. And the — so, to summarize, those are the players who either theoretically or actually were in a position to see this information. But, primarily, and by assignment of their watch duties, sonar and fire control as a minimum should have done this, because the officers of the deck has other responsibilities as well that distract him.
And so my — in everything that I know, I do not think that the ship keyed on this bearing rate, this right six bearing rate of Sierra 13 as part of their calculus of the range of Sierra 13.
However, what I do — and you’ll also note this is only two minutes, roughly two minute period where the ship is evaluating on this short leg here 340 before it makes its next maneuver. So, what I would say in hindsight is because of the abruptness of the transition from the high speed maneuvers, and the shortness of this leg, that this does not constitute a good initial TMA leg.
However, it does constitute enough data for the ship to determine what course it should go to next in order to further develop parameter information on the context that it held at that time.
Now, there is some confusion depending on which statements you review, and the records that I reviewed on how many contacts existed and what bearings they were in in this period of time. But as a minimum the ship expected everybody who would play in this question, sonar, fire control, Officer of the Deck, CO felt that they were at least two contacts to the north, roughly to the north, either side of the north by say less than 30 degrees.
So, this first choice of maneuver was to come to the right to course 120 and that’s this leg right here, 150 feet at 10 knots in order to further develop information on the contact that were to the north of the ship.
Q And sir, why would that have been a course to come to to conduct the second leg of TMA?
A That would have been an excellent course for developing information further on Sierra 13, because that was a course that would put Sierra 13 just aft of the port baffle — correction, just aft of the port beam but forward of the acoustical baffles on the port end of the ship, so you put most of your ship’s speed across the line of sight and you — that’s indicated by the arrow here for the USS Greeneville on this 120 leg. If this is the bearing up to the contact of interest you put most of your speed across the line of sight to develop a change in bearing and a change in bearing to the contact is the type of parameter of most use to our — to our — to the calculus that’s being performed by the fire control system in order to determine automatically what that range is, and the displays are optimized to improve your knowledge quickly if you maximize that change in bearing. And so the ship chose to come to 120 for the reason that it probably wanted to develop further information on Sierra 13.
And in hindsight it went from this arrangement to this arrangement, the blue arrow went from the left of the bearing to the right of the bearing as it changed from course 340 to 120, had it been able to use this leg in conjunction with this leg I think it would have very rapidly seen it was in what we call an overlead situation, and that’s where this arrow is in the same direction as the target arrow, but even more across the line of sight to the right, and therefore low bearing rates such as this do not imply a distant contact. You see, in general low bearing rates, little bearing change with time, even though the ship is driving across the bearing horizontally mean that you have distant contact. But if the orientation happens to be this one where you’re in rover lead you can end up in a situation where you drive across the line of sight, you don’t get a lot of change in bearing over time, but that doesn’t mean the contact is distant.
Now, we have formulas that are thumb rules that are also decks and they use to determine these ranges, and had it applied that formula to this data and this data, it would have seen the range at about two miles.
Had it only applied this leg, there would still be no true indication just how close the Ehime-Maru was.
Q Sir, was contact Sierra 13 the Ehime-Maru in automatic track follower?
A Let’s see. Yes, short answer, yes. But it faded during the high speed turns, and then was placed back in AT up here as it showed here on the chart at 1231 on the Greeneville’s track, at a bearing of 008, Sierra 13 was placed in ATF and my understanding then remained in ATF until the collision.
Q Sir, how good was the sonar contact that Greeneville held on Sierra 13 in terms of signal to noise ratio?
A Well, ATF is automatic tracker follower, and that’s an expression where you essentially can tell the system to automatically track the contact because the signal to noise ratio is good enough, strong enough, high enough so that the system will be able to search either side of it continuously and keep it centered on the right bearing to the contact, and that was the case here.
In general, whenever you see these blue dots, that means the Sierra 13 is an automatic tracker follower. You can see it didn’t work during the high speed turns, so there are limitations on how this system will work, but otherwise it was tracking very consistently outside of the high speed turns shown by the green shaded area.
Q So you mentioned that she was — she held two sonar contacts, I guess is that at minimum, you said? That she held to the north.
A Depending on the statements, there was a contact to the south as well, and so there may have been three contacts, but it’s possible that those contacts were not regained after the ship slowed from the high speed party, either because the contact drove over the hill and was too distant any more, the signal path changed as it changed its environment it was operating in and other things that can affect that.
Q But, sir, the maximum number of contacts that she had at this time was three, is that your testimony?
A Yes, that’s my recollection.
I was a little unsure when I did the investigation because there were some disparities in reports from the various operators of which contact numbers existed at this time, and what their direction was. So I also had a little uncertainty, except that I think Sierra 13 was consistently held to the north.
Q Sir, from a contact management point of view, how would you describe managing three — three sonar contacts? Would that be a challenging situation, or — or what?
A Well, actually for a ship like Greeneville that’s probably an easy picture to try to maintain. We sometimes find these ships have to operate in counters where they simultaneously hold 15 or 20 sonar contacts, so these ships are very capable of multiple contact management.If you have a whole lot of contacts, what you try to do is identify the closest ones and focus on them, and also perhaps put them in sectors so that you can find water where you’re at least opening them, even if they’re rather close.
But a three contact situation in general would be what I would call an easy problem for a typical attack submarine at Pearl Harbor.
Q The Greeneville actually came to periscope depth without any problem, so why is all of this discussion with respect to TMA germane to the collision?
A There are two fundamental reasons why it’s very germane. First of all, this information should be used by the ship to focus its periscope depth period, to get the most use out of its periscope depth period. If it’s diligently using this information, once at periscope depth then you’re combining all that information to optimize the visual search and the electronic search and to disprove preconceptions that you may have a close ship.
One of the things that’s acting here is the human mind set which is if you go to periscope depth not expecting to see anything, then you’re less likely to see anything than if you go to periscope depth expecting to see something. Because that’s the way the human mind works. So, a good ship will in general train itself to be expecting those contacts and to look down those act bearings as correlated between sonar or the periscope, give it a good strong how power look at an appropriate depth and disprove that they’re close, instead of assuming they’re not unless you happen to see it.
So it’s a mindset and it’s a correlation with data. The other fundamental reason is that when a CO is going to do an emergency blow, and remember all of this is happening preparatory in steps to doing an emergency blow, example and evolution where once you put the air in the ballast tanks the ship is going to go up to the surface so you have an issue of safety and you’re going to want to make darn sure that you’ve done a complete correlation of all the tactical information available to you and integrate that before you make that decision to go to periscope depth — I mean to emergency blow. Your sonar history is a vital part of that decision-making that you want to integrate in.