HUMAN FACTOR

   CASE STUDY

One clear night in December, one ocean-going vessel sailed out of Hakata port in Japan. At 0348 hours, captain look around the Fukuoka Wan. There is no fishing vessel in sight. Captain decide to ring full away the vessel and sail with full sea speed. At 0400 hours, chief mate took over the watch and fixed the ship’s position. As a good practice, chief mate acquire the targets outside of the Fukuoka Wan with ARPA. After the target is marked, chief mate concentrate on the course change and steady on the new course of 345(T) at 0405 hours. Chief mate check the targets outside the Fukuoka Wan in the ARPA screen found the target sailed on course 240(T) with 8~9 kts speed had collision risk with own ship. 2-3 miles after this vessel, another vessel sailed at approximate same course and speed. At the late night, chief mate assume the vessel will alter course and enter the Fukuoka Wan. For clarifying the intention of the southwest bound vessel, chief mate try to arouse the attention of the crossing vessel by the flesh light, followed with the VHF calling. There is no response from the approaching vessel although chief mate try many times. As two ship get closer and closer, chief mate alter course to 330(T) to keep out the way at 0413 hours on the same assumption. The southwest bound vessel did not alter course to portside as the chief mate’s expectation, she just keep on the original course and speed. 

When the collision risk seems imminent, chief mate take action to alter course to portside. The collision happened, anyway. Two vessels scratch each other at 0424 hours. The angle of blow is 10 to 15 degree. The collision position of the ocean going vessel is at starboard quarter. The damage is not serious. Some shell plate and frame is dented, but not broken. No crew injured and no oil pollution took place. The investigation after the collision revealed the coastal vessel had no man on the bridge when the collision happened. That’s why chief mate cannot get any response from the coastal vessel. However, no man on the watch still cannot relieve the obligation of the give way.        

COMPLACENCY:

false status of security mentally although the physical threat is still present. Mentally, the conscious is under low aroused status and feels self –sustained without any solid ground of reason, almost in an unconscious status. For example: Follow the command, SOP’s or order from the management unconsciously without confirm or thinking. 

In this simple case, the complacency comes 

-1  From the fully equipped bridge

In the bridge, the false complacency may derive from the communication equipments we have. Thus, the OOW lost the anxious of the collision risk and try to establish the last minute communication to avoid the collision. 

-2. From the routine work we do

For everyday routine watch on the sea, the man on the bridge seems most unproductive. To make the most of it, the man on the bridge sometimes will assign some other functions out of the bridge. Thus, the basic watch safety is slacken  

-3. From the task we take

After some rush hours in the bridge, everything goes quite and nice again. The course has been correctly set on the auto-pilot and engine runs smoothly. The man on the coastal vessel’s bridge feels better and better. Finally, all the awareness vanished. OOW then decide that it is the time to take care other errands. The coastal vessel just sailed out of the Kanmon strait, one of the most narrow and busiest strait in Japan.

-4 From the expectation we have

The coastal vessel sailed the same route almost every week. There is some expectation out of the routine voyage experience. No vessel will leave the Hakata in this early hours: 0410 hours.

The ocean-going vessel had another expectation out of past experience that the coastal vessel will enter the Hakata port and did not aware that it is still too early for the coastal vessel to berth in Hakata.

We will ignore the new situation out of these expectation, even did not aware that we are already in the status of expectation.

-5 From the fatigue/stress/frustration we had

Under the physical fatigue/mental stress/emotional frustration, man cannot concentrate on the details of the work at hand. The ocean-going vessel had just sailed out of Hakata in the early morning; the chief mate may had some rough hours already.

-6. From the guru we work with

If there is a master we trust in the bridge, the OOW will not question his decision and double check his judgment. The OOW will fell ease and comfort in the watch, thus arouse the status of complacency. The modern guru comes in another shape: ARPA. ARPA has its limitation in interpreting the risk of collision, especially in the short distance and constant course change. 

-7. From the privilege authorized by the convention

The watch officer of the coastal vessel left the bridge in the early morning, based on the assumption that no vessel will leave harbor area in this time. Even there is a vessel leaving the harbor area, by the COLREG, the leaving vessel should give way to the coastal vessel. These are the possible mental sources of the complacency may derive. 

Other sources may derive 

-8 from the management lever.

Did not ask the employer to responsible for their behavior.

Did not reckon the achievement they got.

Punish the creative thinking.

Ask the employer only follow the order.

Statically, human factor contributes two third of accidents in almost all kind of human activities. For the rookie, the accidents derive mostly from lacking of knowledge or experience. For the guru, the accident derive from temporally absent of mind or lost of concentration. It is obvious that the rookie should not take all the responsibility at one time. He should be proper trained and educated with the basic knowledge he needed. Then, execute part of watch duty supervised by the qualify personal. Even in a routine bridge watch, it still consisted of many aspects of skill and knowledge. Beside the general knowledge of the third mate license, the OOW need at least two other GMDSS, ARPA certificate which are very sophisticated skill. He, then, will concentrate his effort in absorbing the experience and skill from his superior. The room left for complacency is very narrow. The complacency only comes when he think he is capable of this job. This is the real problem begins.

To overcome the complacency status,

there are some ways.

Understand what complacency is.

Make some case study to realize the outcome of complacency.

Simulate the malfunction of the automatic system and think the proper procedures to follow.

Arouse the awareness by interact with other member on bridge.

Raise the curiosity of the emergency procedures’ correct steps.

Challenge the SOP.

Let others to check your emergency priority.

Exchange your observation and experience with others.

Ask yourself what you will do in some other meeting situation.

Re-think is there anything been forgotten in your expectation.

Think the consequence of your action, is there some other way out.

Well planed to avoid the physical fatigue/mental stress/emotional frustration.

Call the master in need to reduce the stress lever.

Summon other assistance to the bridge.

Beware of your own physical status to avoid the fatigue.

Exam your own feeling and find suitable way to relief or depress. 

Only one glance of these ways, we can tell that it is not an easy job to avoid an accident. 

For the elder and more experienced OOW, temporally absent of mind or lost of concentration look like some kind of excuse. In the modern medical report, there is a disease that makes a person lost working memory for a very short interval and he just forget what he should do at the moment. It is believed that it is out of miss connection of nerves between different parts in our brain or the connection of the nerves in our brain had collided each other. However, this is not all the case. The reason is still the complacency derive from physical fatigue. 

Personnel awareness against the stimulus

From the drawing below, we can see the awareness or response to the stimulus is built up slowly to cope with the situation. After some time period lapsed, the fatigue comes suddenly. The concentration and awareness dropped abruptly without our own perception. 

The time needed for raising the awareness to cope with the stimulus is 15 minutes for the reliving officer to take over the watch. For a ship’s master, there is no such time to spare. This does not mean the captain can not handle all the risk. 

-1 Under the pressure, man will

More concentrate on the things he thinks is important and take other things as irrelevant.

Lost working memory and hard to memorize some short term details.

Compress his long term memory to those procedures he been trained most frequently.

Change his standard of the risk strategy to more swift but not so précised one.

Suffer the prolonged decision making period and the reduced judgment to the space relation.

Need more hints to establish a correct responding to a simple fact.

All and all, the pressure makes one man’s ability to handle the complicated operation much more reduced to an unbearable stage. Thus, we should never assign too much work to a novice if we hope he will still in love of this career. For a ship’s master, he has the ability to use his knowledge to chunk the complicated operation into some useful clue and set up his priority to handle the situation. That’s why this book will be a great help to the mariner. Here offer more knowledge and visual signs to access our traffic situation. For those did not equip with necessary knowledge and experience, there is a simple remedy. Take your time. Get up the bridge early.

-2 Four stages of the body response to shock

For a one man team, there are actually four stages of his body response to the shock.                 

Alarm stage: This is caused by sudden exposure to the stimulus for which our body is not prepared. At the start, there is a state of shock: the heart beats rapidly, loss of muscle tonus, temperature and blood pressure fall. By the static, 90 % people will suffer this stage, others don’t. 

Recovery stage: Shortly afterward, there is an anti-shock, a strong reaction to the shock, in which all the defensive mechanisms are mobilized for resisting the alarm factors. 

Resistant stage: All the senses adjust to the external pressure, and the symptoms of the alarm stage disappear.

Fatigue stage: The reserved energy to cope with the stimulus is limited. Prolonged stress of same type will weaken it to a point where the symptoms of alarm stage all coming back. Only at this stage, our body will not recovery again.

There is a shock stage in and out our body system. By the very rare case, 1 or 2 % people will stay in the first stage of shock and never recovery from it. When an emergency situation occurs the alarm stage can be so deep as to cause one of following malfunction of our senses. Our mind went blank, cannot catch breath, cannot move, cannot see anything.  The first thing in the emergency procedure for a OOW is to call the master to the bridge. When the captain rush up to the bridge, he will expect OOW can give him some briefing of the situation. What if OOW was still in the shock stage ? Part of the master’s due diligence of prudent seamanship is expecting the possible venue of this kind shock will likely to happen and stay with the OOW in the bridge before any stress level accumulated. 

Mantle stage when a collision happened

Even a competent master, his ability to handle all the situation is still has the limit (see the green part of the drawing).        

Here is where the BRM (bridge resource management) should apply. By proper delegate some working load to some other officer in the bridge, the workload can reduce to a manageable level. From the drawing below, the fixing, radar plotting and communication job were assigned to OOW. Beside some necessary instructions given to the OOW, master then can concentrate on the shiphandling. When the collision risk is building, the stress level also raise up. 

Once the collision happened, the stress raised sharply. To the contrary, commander was just at the stage of shock. There is a deepen gap between our mantle state and the demanding situation. From the chapter one, we know that only the long term memory can help us now. What is the long term memory for this situation? The collision force and direction will make the ship movement in a strange way. If there are other vessel around ship’s route, the first priority will be steady the vessel to avoid the second collision or go aground. 

Relative bearing change

Let’s take a look on the radar plotting sheet made by the lawyer. The collision time is 0424 hours. If OS maintain the original course and speed, OS will have very good chance to pass the target stern. This action can also be justified by the relative bearing changed of the target.

Parallax of an approaching vessel

However, we have to take the parallax into account. The bearing change is one degree at every 3 minutes by the plotting sheet. The shape of the approaching vessel is growing big very quickly as the distance is shorten. The reference point we take to take the relative bearing may not so précised. The bearing change is barely noticeable by eye and we don’t expect the ARPA will do better job in this regard.

Collision risk by bearing change

For avoiding a minimum two ship length possible area of collision, the bearing change has to more than 10 degrees before two N.M. Each circle in the plotting sheet is 0.5 N.M. 2 N.M. for a 15 kts OS is 8 minutes run(15 kts x 8 min=2 N.M.). The bearing in position C-16 is 29 deg. At position C-8, the bearing is 26 deg. The bearing change is only 3 degree at 2 N.M. ranges. Although the target is a coastal vessel, the collision risk should deem exist.

Avoidance action at one N.M. DTC

OS advanced at 15 kts speed. Every 4 minutes advance one N.M. OS alter course at C-4 position, that is one N.M. DTC. It’s 7 SL for a 250 meter long vessel. OS still have ample sea room to avoid the collision. OS alter course from 345 to 330 degrees is not enough. The effectiveness of give-way vessel’s action has to be more than 20 degrees of course change at one N.M. range.

Speed reduction in one N.M. DTC

If OS stopped the engine at C-4 position to avoid the collision(15 kts x 4 min=1 N.M., DTC= 1 N.M.), we assume the final speed is 5 kts. The average speed is 10 kts. Actual speed reduction will be 5 kts. 5 kts x 4 min = 620 meters. This is more than 2 SL, enough for avoiding the possible area of collision. If the original speed had been reduced to 10 kts, the average speed will be 12.5 kts. The speed difference is 2.5 kts. For 4 minutes run, the distance gained is 310 meter. It’s 2 SL for a coastal vessel. Thus, the speed reduction is a feasible option.

Rudder cycling in one N.M. DTC

Rudder cycling technique is developed for stopping the vessel. By proper handling, the ship can be stopped within 6-7 SL. Another important feature of this maneuvering is that the ship will deviate to the side of the first rudder been used if the heading change is within 30 degrees difference of the original course. One N.M. is about 6-7 SL. Rudder cycling is also a very good option. The first rudder been used will also help to reduce the mantle stress been built up, which is very important if other vessel is around.

A complete 360 degree turn in one N.M. DTC

If the complete turn is conducted by full rudder, the advance distance needed will be less than 4.5 SL which is under one N.M. DTC. However, OOW always has the fear to use the full rudder, lest the vessel will lose control of the heading. The full rudder is used for initialing the turn. Once OS begin the swing, the OOW will have the feeling that the bearing change is enough. He will then ease the rudder to slow down the heading change. The moment of salvation will surely come because the DTC is still one N.M. away.

In one N.M. DTC

The distance judgment is more important than the bearing change judgment in short DTC. The bearing change judgment is impeded by the parallax in short range. In this DTC, there still have 3 options to choose. If OOW can spare some seconds to check on the radar screen under the extreme pressure of collision risk, OOW will have more confidence to take the action. If the DTC is less than one N.M., the proper action will depend on how many SL left to the collision spot.