Use of AIS by the Big Boys

[Wxx3]

There is a very interesting discussion of use of AIS and Radar by commercial ships on gCaptain for those interested:

How are you using AIS? - Professional Mariner Forum - gCaptain Forum

Though it starts out about AIS, very good discussion on Radar use and abuse.

Also, I like that the also bring up Radar's limitations because of set-up or attenuation.

 

[kev_rm]

That is an interesting article.. I was surprised by the "AIS is not for collision avoidance" mantra with that group.. Perhaps a different world where they have the bandwidth to tag and track targets.

 

[dhays]

That is an interesting article.. I was surprised by the "AIS is not for collision avoidance" mantra with that group.. Perhaps a different world where they have the bandwidth to tag and track targets.

That struck me as well. They seem to have a huge (and healthy?) distrust of AIS position information. That is something that I've never considered.

That discussion has caused me to rethink how I use the radar.

I have used the radar for target tracking, instead of the AIS. I am fortunate to have two displays. I put AIS information on my chart display and use the other display for target information. I add targets manually only.

I do need to get better at tuning the radar however.

 

[tiltrider1]

Pilots in the Puget Sound turn off B class AIS and do all collision avoidance by radar. AIS is great at letting you know what's coming at you but the lag time will kill you in the fog.

 

[twistedtree]

I just don't understand this blanket dismissal of AIS as a collision avoidance tool. Why wouldn't you use all tools available to you? In fact, you are required to do just that.

Any why wouldn't you cross check what your various tools are telling you?

And if you see a disagreement between what your tools are telling you, why wouldn't you want to understand why?

Yes, AIS can have errors and/or delays, but errors in position are very rare, and will be obvious instantly when comparing AIS to a radar return. Delays in AIS position updates definitely happen, but it takes about 2 seconds to see what's going on as the radar return advances, then the AIS target jumps to catch up. So I don't see how it's such a big deal.

ARPA can have issues too, not just AIS. Just use a Simrad Radar and you will see how wrong ARPA can be. And you can lose the target is rain or sea clutter. And you can get target "swap" when a target passes close to another object and the ARPA lock jumps to the other return rather than following the original return.

I think all this is just part of knowing how your equipment behaves, and learning how to use it. I actually find it quite disheartening that so-called professional captains actively ignore AIS when evaluating collision risk.

 

[psneeld]

Learning to use both as tools and not solve all boxes is the trick.

 

[twistedtree]

Learning to use both as tools and not solve all boxes is the trick.

Agreed, but that seems to complicated for many of the gCaptain participants.

 

[Codger2]

Agreed, but that seems to complicated for many of the gCaptain participants.

 

[psneeld]

Agreed, but that seems to complicated for many of the gCaptain participants.

We often noted in shipboard aviation, the surface fleet had an odd way of complicating things.

Possibly understandable in combat, but almost dangerous in peacetime....maybe that almost is becoming actually.

 

[LarryM]

The IMO issued Resolution A.1106(29), adopted on 2 December 2015 entitled REVISED GUIDELINES FOR THE ONBOARD OPERATIONAL USE OF SHIPBORNE AUTOMATIC IDENTIFICATION SYSTEMS (AIS).

The following guidelines excerpted from it may, in part explain the "Blanket Dismissal" attitude referenced earlier.

"Users are therefore cautioned always to bear in mind that information provided by AIS may not be giving a complete or correct "picture" of shipping traffic in their vicinity. The guidance in this document on the inherent limitations of AIS and their use in collision avoidance situations (see paragraphs 40 to 44) should therefore be observed."

USE OF AIS IN COLLISION AVOIDANCE SITUATIONS

40 The potential of AIS as an assistance for anti-collision device is recognized and AIS may be recommended as such a device in due time.

41 Nevertheless, AIS information may merely be used to assist in collision avoidance decision-making. When using the AIS in the ship-to-ship mode for anti-collision purposes, the following cautionary points should be borne in mind:

.1 AIS is an additional source of navigational information. It does not replace, but supports, navigational systems such as radar target-tracking and VTS; and

.2 the use of AIS does not negate the responsibility of the OOW to comply at all times with the Collision Regulations, particularly rule 7 when determining whether risk of collisions exists.

42 The user should not rely on AIS as the sole information system, but should make use of all safety-relevant information available.

43 The use of AIS on board ship is not intended to have any special impact on the composition of the navigational watch, which should continue to be determined in accordance with the STCW Convention.

44 Once a ship has been detected, AIS can assist in tracking it as a target. By monitoring the information broadcast by that target, its actions can also be monitored. Many of the problems common to tracking targets by radar, namely clutter, target swap as ships pass close by and target loss following a fast manoeuvre, do not affect AIS. AIS can also assist in the identification of targets, by name or call sign and by ship type and navigational status.

Then, this article from The Maritime Executive entitled Collision Avoidance: AIS Versus ARPA makes a case for Data Segregation of AIS and ARPA data. Also, the Best Practices / Guidance are useful for those who use both systems.

 

[twistedtree]

So it acknowledges

1) the value of AIS

2) that it should be the ONLY tool you use, which can also be said of any other nav tool.

3) that is can help track where ARPA may be challenged

That seems to say to opposite of "do not use it for collision avoidance"

 

[Insequent]

So it acknowledges

1) the value of AIS

2) that it should be the ONLY tool you use, which can also be said of any other nav tool.

3) that is can help track where ARPA may be challenged

That seems to say to opposite of "do not use it for collision avoidance"

#2 I think you left out 'not'. ie .....not be the only tool...

 

[twistedtree]

#2 I think you left out 'not'. ie .....not be the only tool...

Yes, thanks.

 

[dhays]

Well, this summer I was very happy to have AIS crossing Juan de Fuca. No fog this time, but I had to cross the VTS lanes and was fighting a two knot current. This meant that I was crossing very slowly. A container ship was coming out of Admiralty Inlet and I wasn't sure which way he was headed. A quick call on 13 got a reply from him and I was able to make an early course change to be well away from him.

Not easy without AIS. Being able to hail them by name makes a huge difference.

 

[tiltrider1]

I use AIS for long range planning and radar for avoidance. With in VTS, AIS can let you know if a ship has made a course change or is about to make a change, this gives you better knowledge for making that go or no go decision when crossing a VTS channel.

 

[psneeld]

Or a VHF radio transmission.

 

[twistedtree]

I guess my point, and it's really not my point - it's engrained in the colregs - is that you should use both, not one or the other. For collision avoidance, use your radar, and your AIS, and your eyes, and your VHF, and anything else at your disposal. That's what it's all there for.

 

[psneeld]

The biggest threat of technology is complication of data that is easily resolved by one or other means.

If one becomes distracted by trying to obtain more than necessary data, therein lies the danger.

The average recreational boater I have instructed is certainly overwhelmed by 2 or 3 pieces of electronic gear...we keep adding.

So only to a point does more equal better...its where your training and practice improve situational awareness, not just adding gear....especially gear that has to be interpreted for its shortcomings in some regards.

The airlines, military and I bet many other high performance organizations agree.

Tools in a toolbox that are misunderstood can be as dangerous as not having them at all...better to rely on other means.

If one cannot cross a simple traffic separation zone or VTS zone without AIS, I really feel for you.

Places like the English channel and other extrodinarily high traffic areas are a different story, so are river systems with huge tows around a corner that you may not know of until the last moment without AIS.

 

[tiltrider1]

I see we have an expert here. Some one who is experienced at pulling a 3kt log boom across a busy VTS channel with 2 kts of current. Channel 14 tells me if there is traffic in the area. AIS tells me if I can consider the cross. AIS class B is turned off, to many icons on the screen, unable to see all the little fishing boats in the VTS lane other wise. Radar tells me if I am going to collide with any of the commercial, pleasure or rec fishing boats.

Yes, use all the tools, but use them in the correct order.

I like the way some people have all the answers for everyone even though they have never left their home port.

 

[twistedtree]

I see we have an expert here. Some one who is experienced at pulling a 3kt log boom across a busy VTS channel with 2 kts of current. Channel 14 tells me if there is traffic in the area. AIS tells me if I can consider the cross. AIS class B is turned off, to many icons on the screen, unable to see all the little fishing boats in the VTS lane other wise. Radar tells me if I am going to collide with any of the commercial, pleasure or rec fishing boats.

Yes, use all the tools, but use them in the correct order.

I like the way some people have all the answers for everyone even though they have never left their home port.

You're presumably talking to psneeld and/or me. I haven't pulled a log tow, but he might have. And we have both been out of port once or twice.

 

[psneeld]

Sad that people did it for a long time before AIS with zero ptoblems doing tbe mental calculations.

Sure it can make it easier like gps does for all of us. Pros using it with experience and training are a diffetent animal from the average TFer...but I mentioned that before.

Bet most boats here are piloted and cruised differently than a log boom tow.

People constantly warn me about comparing professional use/acts versus what this forun is really about, and for that I am constantly sorry when I mix the two unecessarily.

I am considered an expert in accident investigation and cockpit ergonomics and crew coordination, but even without those quals...there is tons of info on info overload one can google.

I have left homeport ( if you consider a bunch of the western hemisphere from Pine Island Bay, Antarctica to Nome, Alaska to Nova Scotia leaving homeport) and have towed barges well outside my towboat limitations. Nothing new and one possibly shouldnt make assumptions about the actual field one may not have expertise in.

 

[dhays]

I use AIS for long range planning and radar for avoidance. With in VTS, AIS can let you know if a ship has made a course change or is about to make a change, this gives you better knowledge for making that go or no go decision when crossing a VTS channel.

That was the situation I faced last month. I was looking at a container ship and even based on the AIS listed destination (which even with commercial traffic is often wrong), I didn't know which of three possible directions they were going to head when they reached Sierra Alpha outside Admiralty Inlet. I thought they would be heading West, but wasn't sure. If I turned East to pass astern of them, and it turns out they were actually going to be heading NW or NE, then I would be turning into their path.

A radio call to the ship cleared that up and was able to alter course to the East so I would be well clear of his stern. AIS told me who to call, it also gave me (at least in this case) more accurate course and speed info than my radar.

In the future, since I am a slow boat, I'm going to try to be further to the East or West of Sierra Alpha.

 

[Codger2]

I like the way some people have all the answers for everyone even though they have never left their home port.

Wrong side of the bed this morning?

 

[tiltrider1]

I was jabbing at psneeld. I should have added an LOL, so you could tell I was making fun of his VTS crossing comment as I assumed he was making a joke as well.

 

[markpierce]

Do understand why ships would not monitor B-AIS for detecting small boats. Most boats don't use it, so radar and vision are the ships' best way to detect small boats. Besides, in crowded waters, ships have limited maneuverability, so boats need to keep out of the way of ships.

 

[psneeld]

Right.....

 

[cappy208]

I have not been on yachts, mega yachts, tugs and ships where all methods of Nav information was not included, considered and used for Nav decisions. (Including AIS)

Class B transceivers DO have a lag in display which makes them suspect. But not ignored. The Mk 1 eyeball is being often overlooked on many vessels and is being replaced in a mistaken over reliance on electronics, plotters and displays.

 

[SaltyDawg86]

It's simple. It's a tool. It should be used as such. Nothing replaces looking out the window.

 

[JDCAVE]

We came down from the Pender Harbour Area last week and up the Fraser River. In doing so I have to cross the Vessel Traffic Separation lanes. It's a busy place with cruisers crossing your path back and forth to the Gulf Islands and a mass of recreational fishing boats off Sandheads. So...

There's this sailboat travelling in the wrong direction in one of the Traffic Separation Lanes. We are both transceiving AIS. We are the stand-on vessel and the bearing vectors suggest a collision situation, the radar suggests a collision situation and my view from the window suggests this as well. So I hail the guy...on 16 and then 9 and then 6. Nothing! Geez! So I change course and pass him on his stern. The vessel is flying a French flag!Meanwhile, I'm not the only kid on the block. There's a container ship bearing down on him. So I get on the Blower to VTS and inform them that they should me mindful of him as he does not respond on the VHS. VTS hails him on the VTS channel, then 16 with no luck, so they advise the Pilot on the container ship. The ship had been monitoring him as well and had to make a move.

The amazing thing is that guy travelled all the way from France without being plowed!

Small fishing boats off the Lightstation (11 o'clock on the 0.75 nm range ring):



Jim

 

[twistedtree]

Mr Magoo. There are lots of them around in all forms.