AIS – Panacea or Pandora’s Box
May 20, 2003
Dennis L. Bryant- New York
According to Greek legend, Zeus had the messenger god Mercury
leave a mysterious box with Pandora. Mercury told Pandora to hold the box for
safe-keeping, but under no circumstances was she to open it. Not long after
Mercury departed, curiosity got the better of Pandora and she opened the box to
examine its contents. Unfortunately, the box contained all the ills and
misfortunes of the world. They promptly escaped and have been loose in the
world since that time.
The word ‘panacea’ is derived from the Greek terms “pan”
(meaning all) and “akos” (meaning remedy). According to the Merriam-Webster
Dictionary, the word means “a remedy for all ills or difficulties”.
The question is which term applies to AIS?
What is AIS?
AIS is an electronic transceiver unit intended to be integrated
with a ship’s radar, gyrocompass, global positioning system (GPS), and other
operational and navigational systems. When fully operational and when
functioning properly, it will provide the officer in charge of the navigational
watch with a radar display that includes a mark for every significant ship
within radio range, each with a velocity vector indicating speed and heading.
Each ship ‘mark’ could reflect the actual size of the ship and its position with
GPS or differential GPS accuracy. By clicking on a ship mark, the officer could
learn the ship name, course, speed, classification, call sign, registration
number, and other information. Maneuvering information, closest point of
approach (CPA), time to closest point of approach (TCPA), and other navigation
information could also be available.
AIS operates in the VHF maritime radio band. It is capable of
handling over 4,500 reports per minute and updates itself as often as every two
seconds. It uses Self-Organizing Time Division Multiple Access (SOTDMA)
technology.
Each AIS system consists of one VHF transmitter, two VHF SOTDMA
receivers, one VHF digital selective calling (DSC) receiver, and a standard
marine electronic communications link to the shipboard display and sensor
systems. Position and timing information is normally derived from a GPS
receiver and generally includes a medium frequency differential GPS receiver.
Other information broadcast by the AIS is electronically obtained from shipboard
equipment through standard marine data connections. Heading information and
course and speed over ground would be provided by all AIS-equipped ships. Other
information, such as rate of turn, angle of heel, pitch and roll, destination,
and ETA, could also be provided.
The AIS transponder works in an autonomous and continuous mode,
regardless of whether the ship is on the high seas or in pilotage waters.
System coverage range is similar to other VHF applications. Propagation is
slightly better than that of radar due to the longer wavelength of AIS. Thus,
it is possible to obtain an AIS report before the true radar image appears on
the radar screen. The usual range of AIS is 20 nautical miles.
The shipboard AIS unit broadcasts the following information
every 2 to 10 seconds while underway and every three minutes while at anchor:
-
The unit’s maritime mobile identity (MMSI), a unique
identifier for each ship radio unit, assigned by the International
Telecommunications Union (ITU).
-
The navigation status of the ship (e.g., underway using
engine, at anchor, not under command).
-
Rate of turn.
-
Speed over ground.
-
Position accuracy.
-
Longitude and latitude.
-
Course over ground.
-
True heading.
-
Time stamp.
In addition, the AIS unit broadcasts the following information
every six minutes:
-
MMSI number.
-
Ship’s IMO number.
-
Ship’s radio call sign.
-
Name of ship (up to 20 characters).
-
Type of ship and cargo.
-
Dimensions of ship (in meters).
-
Location on ship where the reference point for position
reports is located.
-
Type of position fixing device utilized by ship.
-
Draft of ship (in meters).
-
Destination of ship (at master’s discretion).
-
Estimated time of arrival (ETA) at destination (at master’s
discretion).
The U.S. Federal Communications Commission (FCC) has developed
informal guidance regarding approval of AIS installations on U.S.-flag ships,
but it has not yet promulgated its regulations. Likewise, the U.S. Coast Guard
has issued informal guidance describing the certification process for AIS and
other navigation equipment mandated by the SOLAS Convention. Until those two
agencies promulgate their regulations, AIS approval for U.S. ships will remain
an ad hoc process. Type approvals have recently been issued, though, by
the FCC and the Coast Guard for two commercial AIS systems.
Deadlines
There are at least four separate sets of deadlines for use of
AIS.
For ships entering the St. Lawrence Seaway in North America, use
of AIS was required as of the commencement of the 2003 navigation season, March
31, 2003. Portable AIS units are available for rent by ships not having AIS
permanently installed.
For ships transiting the Panama Canal, use of AIS will be
required as of July 1, 2003. As with the St. Lawrence Seaway, portable AIS
units will be available for rent by ships not having AIS permanently installed.
For ships operating in U.S. waters, installation and use of AIS
will be required in accordance with the following schedule:
1. On and after January 1, 2003 for any vessel built on or
after that date;
2. On and after July 1, 2003 for any vessel built before
January 1, 2003 that is a passenger vessel required to carry a SOLAS
certificate, a tanker, or a towing vessel engaged in moving a tank vessel; and
3. On and after December 31, 2004 for all other vessels
built before January 1, 2003.
For ships subject to the SOLAS Convention of 300 gross tonnage
and upwards engaged on international voyages and cargo ships of 500 gross
tonnage and upwards not engaged on international voyages and passenger ships
irrespective of size, installation and use of AIS is required in accordance with
the following schedule:
1. Ships constructed on or after 1 July 2002;
2. Ships engaged on international voyages constructed
before 1 July 2002:
a. In the case of passenger ships, not later than 1 July
2003;
b. In the case of tankers, not later than the first
survey for safety equipment on or after 1 July 2003;
c. In the case of ships, other than passenger ships and
tankers, of 50,000 gross tonnage and upwards, not later than 1 July 2004;
d. In the case of ships, other than passenger ships and
tankers, of 300 gross tonnage and upwards but less than 50,000 gross tonnage,
not later than the first safety equipment survey after 1 July 2004 or by 31
December 2004, whichever occurs earlier;
3. Ships not engaged on international voyages constructed
before 1 July 2002, not later than 1 July 2008.
Concerns re AIS
Problems have been observed with regard to AIS installations to
date. Ship''s static data sometimes is loaded incorrectly or not present at
all. For instance, ships have reported dimensions via AIS that are obviously
incorrect. Some ships are not transmitting heading information via AIS,
possibly because the connection of the ship''s gyro compass has not been properly
made. On some ships, although the AIS system seems to be connected to the gyro
compass, the heading information being reported by AIS is different than the
actual heading. Some shipborne AIS equipment does not respond to shore station
commands. The cause is probably outdated firmware. These early implementation
problems highlight the fact that AIS is a complex piece of equipment that only
works properly when it is fully integrated into a sophisticated navigational
system.
A note of caution is in order. Implementation of AIS has been
advanced because of the inherent maritime security aspects of the system. After
all, if the authorities ashore can automatically identify ships as they arrive
offshore, it makes the job of evaluating risks and allocating scare resources
that much easier. On the other hand, as noted above, incorrect (or false) data
can be accidentally (or intentionally) programmed into the AIS as currently
configured. This would defeat the security purpose of AIS, leading to
potentially catastrophic consequences. Further, terrorists, pirates, and others
of malicious intent can monitor AIS signals to identify target vessels.
Returning to the original purpose of AIS, maritime safety, all
parties should remember the consequences of over-reliance on machines that seem
to provide all the answers. One need only look back to the grounding of the
cruise ship ROYAL MAJESTY on June 10, 1995. The ship was completing a voyage
from Bermuda to Boston when it ran aground on the Rose and Crown Shoal about 10
miles east of Nantucket Island, Massachusetts. The ship was 17 miles off course
when the incident occurred. Damage to the ship and lost revenue were estimated
at $7 million. Subsequent investigation revealed that the ship’s automated
navigation system had been programmed to rely on its GPS receiver. However,
less than one hour after departing Bermuda, the GPS antenna came loose,
disabling the GPS. The integrated navigation system automatically defaulted to
its dead reckoning navigation system, which does not compensate for the effects
of wind, current, or sea conditions. The audible warning system had been
disabled and the warning light was displayed only in the chart room. No one on
the bridge during the 34 hours between the loss of the GPS signal and the
grounding noticed that the ship was off course. None of the other available
navigational tools were utilized. The incident provides a valuable lesson in
what can happen when reliance is placed in any one system to the exclusion of
other systems, including common sense.
Conclusion
The answer to our original question is that AIS is neither a
panacea nor a Pandora’s box. It is just another tool in a large and growing
tool box made available to masters, deck officers, and others to enhance
maritime safety and security. It is only as good as its maintenance and the
training provided to its users.