Chapter 3: Situational Awareness for Junior Officer

Situational awareness for Junior OOW

Figure 3-1 Diagram of navigational track of SANCHI and CF CRYSTAL

So, it’s Sanchi case again. Only this time we will look into the Radar see what 3/O had seen more than visual data. Measuring from track of these two vessels, M.V. CF Crystal was at compass bearing of 026 degrees from M.V. Sanchi. In relative bearing is 028 degrees green for Sanchi. The distance of CF CRYSTAL is 3.5 nm from Sanchi.  The bearing whether it is compass or relative are almost the same until the collision happened. This is an extreme case where no actions been taken at all by both vessels from the beginning till the last end. This is a very bad sign where the collision avoidance actions are lacking from any stage of collision risk. Sanchi 3/O had distracted by a small fishing boat ZHEDAIYU 03187 kept calling SANCHI on VHF radio who had a collision risk at 1938 hours, 2 minutes before CF Crystal collision Time 1950 hours. How can we know these? 

Read the collision risk from collision point, line and area  

Please refer to figure 3-2 two vessels in collision course with speed vectors display. These two vessels have their course line laid along their speed vectors.  Actually, speed vector is part of their course line in the specified time frame. Usually the speed vector is set to 9 minutes in Sanchi’s case or 6 minutes are most commonly used on bridge. 3 minutes speed vector is rarely used because the display range used most is in 6 NM or 3 nm. The position show on this figure 3-2 is 2215 hours. 

If the speed vector setting is 6 minutes the collision time is 2215 + 0006 = 2221 hours.

If the speed vector setting is 9 minutes the collision time is 2215 + 0009 = 2224 hours.

If the speed vector setting is 3 minutes the collision time is 2215 + 0003 = 2218 hours.

How can we know these collision times are hard to tell in mathematical way? But it is obvious if we read it in the figure. The collision position is always where two vessel’s course line intercept each other. When these two vessels arrive this collision position at same time the collision happen. If we can arrange ownship’s course line properly to avoid transit through other vessels course line we reduce a lot of collision risk. This is the basic safety concept of voyage planning. Collision consist of an important feature that is timing. In bad timing we have collision. If we have different timing to pass collision position the collision will not happen. How can we know the timing is good or not? It depends on two vessel’s arriving time at collision position. 

If both vessels arrive collision position at the same time the collision will happen. If two vessels arrive collision position one by one the collision may not happen immediately as vessel has massive volume and largest dimensions than any artificial machinery on Earth. One vessel may pass collision position half way and other vessel arrive same collision position cause the damage. Also, we have to take vessel’s sluggish turning 3 minutes time into consideration. If the time difference of two vessels passing collision position less than three minutes the collision is hard to avoid. 

The speed vector we used to detect collision risk is collision line. In figure 2-15, last 3 minutes True motion speed vector is our space ship. We may release this space ship to 6 minutes or longer speed vector length to test collision point. The two vessel’s speed vector is crossed in its last three minutes as figure 2-14, 6 minutes True motion speed vector and 3 minutes collision risk area. 

The last 3 minutes part of speed vector is our collision area (= last 3 minutes distance run of current speed). 

In figure 3-2, two vessels in collision course with speed vectors display. They pass same collision position at same time the collision will happen. Although we don’t know after how many minutes they will collide we can check on the ARPA or AIS setting to know the time.  

Figure 3-2 two vessels in collision course with speed vectors display

Positive identification of collision risk by crossed point of two vessel’s speed vector

Figure 3-3 Rdar screen with inly help of target trails

In 1935 hours, the radar screen has many target echoes and ownship speed vector setting at 9 minutes with ownship speed 10.4 knots, heading 358⁰ degrees now, 

Ownship speed vector length is 10.4 x 0.15=1.56 nm, This speed vector distance run  

No speed vector display by ARPA or AIS data although AIS target display setting is all. 

No speed vector of target, we have no collision detection line to help. 

Setting of trails (target’s past position on radar) is true motion ground stabilized, trail length is 2.5 minute. 

True trail presents true target movements depending on their Speed and Course Over the Ground (SOG and COG) where target is going to. Target’s trail can show two things: first is to make target echo size more prominent on screen. Second is to give rough idea of target’s speed and course by comparing her length with another vessel. Sometimes the target trail is the only help we can get from the radar screen especially when the traffic is heavy and rough (see figure 2-9) . It is very important we know how to use trails properly. With the help from trail 3/O tried to get the bearing and distance of a big echo shown on radar screen figure 3.3. After ten minutes 3/O forget what he had seen in radar screen about this target’s data because it’s all digital data.

This target data shown on ARPA are bearing 023⁰ degrees and distance 5.4 nm away. Ship’s cursor is on CF CRYSTAL. At 1946 hours, 3/O refuse to take action. 3/O: Starboard? Why?  He had forgotten what he had seen at 1935 hours ARPA’s screen.  3/O: ...It's a small vessel, right?

It is not foolish. It is human nature in our short-term memory capacity. This kind of troublesome is what we try to overcome in this book.

As a competent 3/O, target distance 5.4 nm is kind of signal to take some action to access collision risk if 3/O had not taken care of in earlier lookout duty. 5.4 nm distance is what we see in Figure 2-22: vessels obligations in collision avoidance varied in certain distance. If it is not 3/O action distance to alter course it must be 3/O evaluation distance to check his compass bearing as COLREG rule 7: collision risk shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change. If 3/O decide to alter course this bearing means ownship can alter course 25 degrees (from 358⁰ to 023⁰) to starboard side to give way as COLREG requirement: Any action to avoid collision shall be positive, made in ample time and with due regard to the observance of good seamanship. 

There is another vessel ZHEDAIYU 03187 on the radar screen, about bearing 038⁰ degrees distance 3 nm away which was in smaller trail echo and shorter trail length. 

-3/O did not set fixed range ring to help reading target distance immediately. This means 3/O did not care about target distance due to slow speed ownship has. Even for a 3 nm target ownship still has 10 minutes time to handle the situation. This is a slow-paced practice which did not help in our situational awareness. 

-We all will overlook some items sometimes due to our short-term memory always overflow and forget data no matter it is important or not. To help our short-term memory we need more clues to react when required, like fixed range rings.    

-in the starboard side of SANCHI, there are 5 targets without acquired by ARPA. No speed vector displayed by ARPA or AIS. If no speed vector in the screen it is hard to detect collision risks by target trails only in 1935 hours.

     Figure 3-4 CF CRYSTAL and ZHEDAIYU 03187 with AIS speed vector

At 1939 hours, M.V. Sanchi COG 358° and SOG 10.4 kts. The 9 minutes speed vector generated from AIS collision alert show on ARPA display as figure 3-4 above. Fishing boat ZHEDAIYU 03187 is on bearing 040⁰ degrees (T) x dist. 2 nm, and CF Crystal is on bearing 026⁰ degrees (T) x dist. 4 nm.

-Positive identification of collision risk by locating crossed point of two vessel’s speed vector. The collision Position of Sanchi and ZHEDAIYU 03187 located exactly at end of Sanchi 9 minutes speed vector where Sanchi will pass collision position earlier than fishing boat. The collision time is 1939 hours + 9 minutes= 1948 hours. The collision position of Sanchi and CF CRYTRAL is not obvious in 9 minutes speed vector display in this figure. We know the collision time of CF CRYSTAL and SANCHI is at 1950 hours in formal investigation. Fishing boat ZHEDAIYU 03187 had a collision risk at 1948 hours, 2 minutes before CF Crystal actual collision Time 1950 hours. If OOW can read this RADAR display by speed vector as we discussed before, they can feel the collision risk by seeing it. This is first stage at situational awareness of radar lookout. Read collision risk in speed vectors.

-Situational Awareness of radar lookout: DTC

Get the feeling of risk by speed vector then OOW should check the collision time by speed vector display time setting. OOW should be able to read the distance to collision position (DTC) from ownship by cursor, or fixed rang ring setting. The distance and time to collision point are important due to our space ship status (ownship turning circle advance needs 6 times ownship’s length and time required 3 minutes). The distance and time on speed vector is proportional to the collision position. The speed vector moves ownship from present position at center of radar to the end of the vector. If the collision position is at half length of speed vector the collision time is half the time of speed vector displayed and the distance to collision is half the distance run of this speed vector represented. For a 20 knots vessel, if the speed vector setting is 6 minutes and one collision position locate at half way from ownship to the end of ownship’s speed vector then collision time is three minutes to go (6/2=3 minutes) and the distance to collision is 1 nm (half distance of 6 minutes run of speed vector).  This is second stage at situational awareness of radar lookout.

-In 1939 hours, situational awareness are as follow: 

l  Fishing boat ZHEDAIYU 03187 is on bearing 040⁰ degrees (T) x dist. 2 nm, from radar cursor

l  has collision risk, 9 minutes speed vector crossed at end of speed vector

l  time to collision= 9 minutes from now, collision at 1948 hours = 1939 + 9 

l  distance to collision = 9 minutes Ownship speed vector length =10.4 x 0.15=1.56 nm

- CF Crystal is on bearing 026⁰ degrees (T) x dist. 4 nm. This may read from cursor

l  has collision risk, more than 9 minutes speed vector time

l  time to collision> 9 minutes from now, collision later than1948 hours  

l  distance to collision > 9 minutes Ownship speed vector length 1.56 nm

- Tell me how to solve the CF CRYSTAL collision situation in current mystery?

In Sanchi case at 1939 hours: ZHEDAIYU 03187 kept calling SANCHI on VHF radio.

3/O said: Oh, he's talking to another one. You know, never answer these calls. 

- Maybe 3/O is right? MCA also warned VHF might have problem to identify the correct communication party we are talking now. This is true for open sea when no other parties can help in these situations. 

- In roadsteads, harbours, rivers, lakes or inland waterways connected with the high seas where the operation of special rules made by an appropriate authority shall not be interfere by COLREG or any other conventions.

- It is not always right ”never answer these calls” as 3/O said.   

3/O said: Because if you don't answer, it is not ok to action. But if you answer, he seems ... he confirms with you about his action.    

- If you don’t answer, fishing boat will assume you did not receive the calling then she will not take any action to block your way. 

- But if you answer, he seems ... he confirms with you about his action. 3/O warried if he answered the fishing boat will think he has agreed with the communications of whatever fishing boat had proposed whether 3/O reply is yes or not.

3/O said: So he takes action, whatever he said in the radio and you don't understand. 

-success communication consist of four parts: what he thinks in mind -> what he said in mouth -> what you hear in ear -> what you think in mind. Here 3/O mentioned two more obstacles in communication.  What he said in the radio and what you heard in foreign language. Radio receiving capability and English verbal expression.  

3/O said: But if you don’t answer, he shall be forced to take action to make himself clear, understand?

- But if you don’t answer: the communication chain is broken. No arrangement will be made.

- he shall be forced to take action: It is not in this logic. 

l  The communication purpose of fishing boat may not ask for any arrangement to be made. 

l  It may only want to warn Sanchi their present at her starboard side and collision risk. 

l  The ultimate purpose of communication is to ask Sanchi give way to fishing boat for the collision risk and COLREG compliance.  

l  Fishing boat don’t want your radio answer they want you to give way immediately. 

l  Sanchi don’t need to answer the radio but to alter course immediately. 

l  Sanchi 3/O don’t want to give way to fishing vessel from the beginning. What will happen from 1939 hours no one can tell.  

l  3/O bet his career and job on the hands of a foreign fishing boat master.  

- he shall be forced to take action to make himself clear: 

l  fishing boat may take action to avoid the collision in the first instance by COLREG rule 17 “may however take action to avoid collision by her manoeuvre alone” when “the vessel required to keep out of the way is not taking appropriate action in compliance with these Rules.”

l  Fishing boat may take action to avoid the collision from 1939 hours (no radio reply from Sanchi but receive ALDIS signal) to 1948 hours (collision time as speed vector shown) if Sanchi not taking appropriate action.  

l  fishing boat shall take action to avoid the collision in the last minute by COLREG rule 17 “she shall take such action as will best aid to avoid collision” when “the vessel required to keep her course and speed finds herself so close that collision cannot be avoided by the action of the give-way vessel alone.”

l  Fishing boat shall take action to avoid the collision from 1945 hours (3 minutes to collision) to 1948 hours if collision cannot be avoided by the action of Sanchi alone.  

l  Sanchi had not take action to avoid collision with fishing boat but give her initiative to fishing boat.

l  After two minutes of failed radio contact at 19 41 hours, fishing boat started altering its course to port side.

l  When fishing boat “is to keep out of the way the Sanchi shall keep her course and speed.” by rule 17.  Sanchi has to keep her course and speed from 1941 hours to avoid the collision with fishing boat.

l  This situation binds Sanchi’s movement to avoid the collision risk with CF CRYSTAL. From 1941 hours 

AB: And this is not complying to the rules that I must oblige...... Because we don’t understand their language.

-       3/O did not give way to starboard side vessel is not complying with COLREG rule 15 crossing situation: the vessel which has the other on her own starboard side shall keep out of the way.

-       Rule 15 did not mention any language problem but only by the aspect of each other. 

-       Like:  (the vessel) which has [the other] on her own starboard side means [the other vessel] is at (the vessel)’s starboard side.

-       Simple rule is to avoid any confusion created by other means regarding the obligation of give-way vessel.

3/O did not reply AB’s comments. 3/O can change RADAR speed vector setting to 12 minutes to evaluate the collision situation with CF CRYSTAL. 

At about 1941LT, SANCHI's, COG 358° and SOG 10.4 kts. ZHEDAIYU 03187 was around 1.8 nm away. The 3/O asked lookout to give ALDIS signal to ZHEDAIYU 03187. The OOW noticed that the fishing boat started altering its course to port side.

-       ZHEDAIYU 03187 speed is about 9 to 10 knots. This is SANCHI visual check on fishing boat speed vector length with ownship SANCHI SOG 10.4 Kts speed vector length or we can use a divider to take the length of fishing boat to compare with ownship’s length. 

-       3/O asked lookout to give ALDIS signal to fishing boat. Actually, this is not allowed. Who knows what signal AB will send through ALDIS signal? 

-       3/O is in doubt whether sufficient action is being taken by the other to avoid collision, the vessel in doubt shall immediately indicate such doubt by?

-       Because this is common practice of navigation bridge, AB might know the correct signal is “a light signal of at least five short and rapid flashes”. 

-       3/O did not care of his obligation to give way to starboard side vessel but express his doubt by ALDIS signal. This is a indication of doubt not a request to ask fishing boat.

-       ALDIS signal is not right for this moment but it gives the fishing boat some idea that SANCHI is watching at her. 

-       Investigation report did not mention what signal SANCHI AB sent to ZHEDAIYU 03187. 

-       By receiving this ALDIS signal, ZHEDAIYU 03187 take action to start altering its course to port side and SANCHI OOW noticed. 

-       From this moment 1941 hours, copied from chapter 2 COLREG rules 17, SNCHI is stand-on vessel to ZHEDAIYU 03187 who originally is a give-way vessel .

(i). Where one of two vessels is to keep out of the way the other shall keep her course and speed.

• o   - one vessel is to keep out of the way: whether it is reasonable or not, the other shall keep her course and speed. 
• o   - one of two vessels: This one may not be directed to keep out of the way originally. That is to say the one is to keep out the way maybe is a stand-on vessel originally.
• o   - Once a vessel is to keep out of the way, the other shall keep her course and speed no matter who is the stand-on vessel in the first place. 
• o   Give-way vessel lost its initiative to alter course or speed once stand-on vessel take action.