INVESTIGATIONS INTO SHIPBORNE ALARM MANAGEMENT
Conduction and Results of Field Studies
Florian Motz
Research Institute for Communication, Information Processing and Ergonomics, FGAN, Wachtberg, Germany
Michael Baldauf
Department of Maritime Studies, Hochschule Wismar University of Technology, Business and Design
Keywords: Alarm management, Field Studies, Safety of Navigation, Human Factors, Human Machine Interface,
Integrated Navigation Systems.
Abstract: Safe navigation, including collision and grounding avoidance, is the main task of the navigating officer in
charge to ensure the safety of sea transport during a ship's voyage. Modern ship bridges are highly-
automated man-machine systems. With the enlarged number of systems and sensors onboard, and the
increase of automation a proliferation of alarm signals on the bridge is associated. Field studies were
performed on board of ships to investigate the situation with respect to the occurrence of alarms and its
handling by the bridge team. Within this paper the conduction of the investigations, the used methods, and
selected results for two samples of field studies will be presented. An outlook for a future alarm
management onboard is given. The investigations were partly performed under the framework of a national
Research and Development project funded by the German Ministry of Transport, Building and Urban
Affairs, and under the European MarNIS – project, funded by the European Commission, Department for
Energy and Transport.
1 INTRODUCTION
Safe navigation, including collision and grounding
avoidance, is the main task of the navigating officer
in charge to ensure the safety of sea transport during
a ship's voyage from the port of departure to the port
of destination. Modern ship bridges are highly-
automated man-machine systems. Safety and
efficiency of the ship operations are dependent, as
all other complex man-machine systems, on the
communication between humans and machines
during the accomplishment of tasks. Humans can
fulfil their assigned monitoring, control, and
decision tasks most effectively, if the information
flow between them and machines is adapted to the
human skills and abilities (e.g., Lützhöft, 2004).
In the last years a strong increase of modern
information systems on the ship bridges could be
observed. Simple displays and control systems were
supplemented or replaced by complex computer-
based information systems. Information of different
sensors and systems are combined in integrated
navigation systems (INS). In order to support the
mariner effectively on board, a task- and situation-
dependent presentation of the information is a
compellingly need.
With the enlarged number of systems and
sensors onboard, and the increase of automation a
proliferation of alarm signals on the bridge is
associated. Alarm signals coming from various
systems and sensors lead sometimes to a confusing
and difficult manageable situation for the mariner,
which is distracting him from his task to safely
navigate the vessel. Redundant and superfluous
audible and visual alarm announcements are
appearing on the bridge, without a central position
for visualization and acknowledgement of alarms.
To enable the operator to devote his full attention to
the safe navigation of the ship and to immediately
identify any abnormal situation requiring action to
maintain the safe navigation of the ship an alarm
management harmonizing the handling, distribution
and presentation of alarms on the bridge is necessary
(Brainbridge, 1983; Sheridan, 1998).
136
Motz F. and Baldauf M. (2007).
INVESTIGATIONS INTO SHIPBORNE ALARM MANAGEMENT - Conduction and Results of Field Studies.
In Proceedings of the Ninth International Conference on Enterprise Information Systems - HCI, pages 136-141
DOI: 10.5220/0002373801360141
Copyright
c
 SciTePress

The International Maritime Organization (IMO)
IMO has recognised this situation and decided to
revise the exiting standards for INS and to develop
requirements for an alarm management system. A
working group coordinated by Germany was
established to progress this work.
For the purposes of a detailed analysis of the
current situation of the management and
presentation of alarms on ships, field studies were
carried out onboard of seven vessels.
The investigations were partly performed under
the framework of a national Research and
Development project funded by the German
Ministry of Transport Building and Urban Affairs,
and under the European MarNIS-project, funded by
the European Commission, Department for Energy
and Transport (Willems & Glansdorp, 2006).
2 INVESTIGATIONS
A series of field studies were conducted with the
following aims:
 determine the occurrence of alarms on the
bridge;
 gain knowledge about the operational needs of
mariners in regard to the presentation and the
operational procedures related to alarms and
INS;
 determine operational problems with the
presentation and handling of alarms and the
operation of INS.
As the management and presentation of alarms is
influenced by the type of ship, the year of
construction, the installed equipment and grade of
integration, the sea area, the training and education
of the crew, the safety standards of the shipping
company (Baldauf & Motz, 2006), these factors
were taken into account to obtain a profound
database.
The investigations were carried out onboard of a
container vessel, a chemical tanker, two passenger
ships, two ferries and a training vessel.
Due to the wide range of results and the different
influencing variables, within this paper two field
studies are selected and described exemplarily to
give a detailed overview of the situation.
2.1 Methods of Investigation
Two methods were applied to fulfil the defined
objectives:
 Recording (manually) of the occurrence of
(navigational) alarms on the bridge;
 Interviews with mariners by means of
structured questionnaires.
2.1.1 Recording of Alarms
The data collected was the actual frequency of
alarms on the ship’s navigation bridge. Onboard
newly built ships a Voyage Data Recorder has to be
installed. According to IMO performance standards
such systems have to continuously record only
selected main mandatory alarms of the bridge
equipment. These recordings were therefore
insufficient for the investigations.
The data was recorded manually in an prepared
electronic data file specially designed for the
purpose. Records were kept on:
 time/date the alarm appears;
 kind of alarm;
 system/device the alarm was announced;
 the alarm settings and limits;
 the presentation (visual/acoustical);
 the handling/reaction by the bridge team;
 the navigational situation;
 additional remarks.
Special focus was laid on the assumed
dependencies of frequencies from sea areas. For the
purposes of the studies the navigational situations
were defined by a group of experts as "open sea",
"coastal" (e.g. traffic separation as defined by IMO,
coastal waterways, possible to determine position
via landmarks) and "confined waters" with four
different special cases: "pilotage districts",
"harbour", "berthing" and "anchorage".
In addition the following was documented with
two tables: the installed equipment (manufacturer /
type), if alarms are switched ON and OFF, how the
alarms are presented visually and acoustically, the
used alarm limits dependent on the navigational
situation.
Basis for the investigations was the analysis of
the technical documentations and manuals of the
sensors and navigational systems installed on the
vessels. Simple changes in the configuration and the
settings of the alarm limits lead to an increase or
decrease of the announced alarms. Furthermore, a
very important factor for the amount of alarms is the
grade of integration of the systems onboard.
2.1.2 Interviews and Questionnaires
Beside recordings also interviews by means of a
structured questionnaire were carried out onboard to
gather the views of navigational officers on the
presentation of alarms on the bridge, operational
INVESTIGATIONS INTO SHIPBORNE ALARM MANAGEMENT - Conduction and Results of Field Studies
137

problems regarding the presentation and handling of
alarms, and the occurrence of alarms.
Additionally interviews by means of a structured
questionnaire were carried out regarding a task and
situation depend information presentation on INS.
2.2 Samples
First sample is a study, which was conducted on
board of a large container vessel of Post-Panmax-
class with a loading capacity of more than 7.500
TEUs. The installed equipment was integrated and
combined in the navigational bridge on a high
integration level, see Figure 1.
Figure 1: Bridge with high integration level.
The investigations were conducted on a voyage
in the North Sea departing from the Port of Hamburg
and arriving at the Port of Southampton. The total
voyage time was 29 hours. During the voyage good
weather conditions were experienced with low
winds and calm sea and only a few rain showers
were encountered during the night.
The second sample is a field study carried out on
board of a medium size passenger cruise vessel with
a total capacity for approximately 1.500 persons
(passenger 1.186 and 370 crew). The navigational
equipment was integrated on the bridge on a high
level as well.
The study was conducted on a voyage in the
Western Mediterranean Sea departing from Palma
de Mallorca, sailing via La Goulette, Tunis to the
Port of La Valetta, Malta. The weather conditions
were good with low winds and calm sea. The total
observation time was 26 hours.
3 SELECTED RESULTS
3.1 Dependencies on Sea Area
3.1.1 Container Vessel
Under the mentioned conditions and used thresholds
a total number of 205 alarms were counted on the
container vessel. This means on average 7,6 alarms
per hour. As this average is not very characteristic a
more detailed analysis was carried out, investigating
the distribution of alarms over the time.
The distribution of alarms on hourly basis for the
entire voyage shows that for the first part of the
voyage (from Hamburg port up to approximately the
entry of the English channel) the number of bridge
alarms was at a more lower average level per hour,
the number rises up significantly during the second
half of the observation period, when the English
channel was passed through, with peak values
between 20 and maximum 26 alarms per hour and
finally again when the channel area was left and the
port of Southampton was entered, with peak values
of 22 and 23 alarms per hour.
The timely distribution reflects the dependence
of the numbers of alarms from the sea area. This
hypothesis is further confirmed when analyzing the
registered alarms in relation to the navigational
situation.
Figure 2 shows the average frequency of alarms
per hour for the navigational situations. It illustrates
that for the navigational situation "coastal" the
frequency of alarms was approximately 4 times
higher than the frequency of the alarm appearance in
"open sea". The lower amount of alarms for
"confined waters" in relation to "coastal" is related
to the fact that alarms, e.g., collision avoidance were
switched off via setting alarm thresholds for the
closest point of approach (CPA) or the time to CPA
(TCPA) to zero when leaving Hamburg harbor and
under pilotage on the Elbe river.
4,9
21,4
9,2
0,0
5,0
10,0
15,0
20,0
25,0
open sea coastal confined
Navigational situation
Frequency of alarms per hour
Figure 2: Average frequency of alarms for sea areas.
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3.1.2 Passenger Vessel
During the observation period of 26 hours a total
number of 220 alarms were counted. This means an
average of 8,5 alarms per hour. As stated before this
average is not very characteristic and a more
detailed analysis was carried out, focussing more on
the distribution of alarms over the time. Especially,
it has to be mentioned, that the average value is to
high as for certain times of open sea conditions data
was not collected.
The distribution of appeared alarms on hourly
basis reflects as for the container ship the
dependency of the different sea areas. There are
several peak values during the whole voyage. The
maximum value of 40 alarms was observed during
departure operations, when the ship left its first port.
Other observed peak values of 17, 25 and 28 are also
related to confined conditions with departure or
arrival.
This is more clearly reflected when analyzing the
registered alarms in relation to navigational
situations. As the observation time varies in the
various navigational situations, the average
frequency of alarms per hour for the navigational
situations is calculated (Figure 3). This shows that
for the navigational situation "coastal" the frequency
of alarms was approximately 3 times higher than the
frequency of the alarm appearance in "open sea".
The high amount of alarms for "confined waters" is
related to the fact, that collision avoidance alarms
were not switched off going in and out of ports,
which lead to a high frequency of Automatic
Identification System (AIS) target alarms. This
clearly indicates a lack of the alarming algorithms
presently applied to installed collision avoidance
systems.
3,2
10,8
26,2
0,0
5,0
10,0
15,0
20,0
25,0
30,0
open sea coastal confined
Navigational situation
Frequency of alarms per hour
Figure 3: Average frequency of alarms for sea areas.
3.2 Dependencies on Equipment
3.2.1 Container Vessel
The system dependent distribution of alarms is
shown in Figure 4. Most of the alarms are triggered
by the radar device followed by the Global
Navigation Satellite System (GNSS) and the gyro
compass monitoring system.
0
1
100
21
29
00
22
29
2
1
0
20
40
60
80
100
120
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e
a
d
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n
g
c
o
ntrol
Trac
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R
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S
)
EC
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Gyro C
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Alarm. Managem. engi
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Gy
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onitor for aut
o
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..
Log
M
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oring
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Equipment
Frequency of alarms
Figure 4: Frequency of alarms per device.
It has to be commented, that nearly all alarms
occurring at the gyro monitor were caused by the
loss of the differential signal at the GNSS device.
Furthermore, in most cases after only a few seconds
the differential signal was available again and the
GNSS began to work in differential mode. This
change was additionally announced by the system
acoustically. However, in every case of loosing
respectively receiving again the differential signal
the officer of the watch (OOW) has to react on the
alarm and has to acknowledge at least the gyro
monitoring system. If not acknowledged
immediately a further alarm was presented at other
connected navigation systems as ECDIS (Electronic
Chart Display and Information System) or track
control.
As the majority of alarms were caused by the
radar device, the specific technical configuration has
to be considered. In the installation of the vessel the
human machine interface (HMI) of the radar device
serves also as integrated interface for in- and output
of AIS data and the track control system.
A detailed analysis for the radar device shows
that the majority of alarms are collision warnings
triggered by AIS. This is an expected result when
taking into account that for AIS the same limit
values were applied as for tracked radar targets and
the option for CPA/TCPA calculation was by default
switched on to sleeping AIS targets. This in
consequence leads to an overload of collision
warnings especially in harbour approaches, where
many AIS targets appear.
3.2.2 Passenger Vessel
The device dependent distribution of the alarms is
shown in Figure 5. Most of the alarms are again
presented at the HMI of radar device followed by the
bridge alarm system, gyro compasses and ECDIS.
The gyro compass alarms are triggered by the
gyro monitoring system, which informs about
INVESTIGATIONS INTO SHIPBORNE ALARM MANAGEMENT - Conduction and Results of Field Studies
139

deviation between course information of first and
second gyro compass. The same alarm appears on
the bridge alarm system. At both systems the alarm
has to be acknowledged independently. The relative
great amount of ECDIS alarms are caused by
deviations of the actual course compared to the
planned course, deviations of the position compared
to the planned route and when a route's waypoint
was approached. The alarms were presented on the
radar device too.
00
132
26
00
25
0
33
1
3
0
20
40
60
80
100
120
140
Heading c
o
ntrol
Track control
Radar (i
n
cl. A
IS
)
EC
DI
S
G
NS
S
E
cho Sound
e
r
Gyr
o
Compass
Alarm. Managem. engine.
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stem
F
ire
al
arm
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B
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llast
w
ate
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a
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Equipment
Frequency of alarms
Figure 5: Frequency of alarms per device.
As for the container vessel the majority of
alarms was presented at the human machine
interface of the radar. Radar was also used as HMI
for the handling of the AIS information as well as
HMI for the track control system. Again, the
majority of alarms are collision warnings and lost
target alarms triggered by AIS. This is an expected
result due to the fact that similar configurations were
found and similar automatic alarm functions were
applied as for the container vessel. However, the
amount of lost target alarms was already
significantly reduced by the OOW by deleting all
targets, otherwise the number of such alarms would
have been much higher.
4 DISCUSSION OF RESULTS
The results of the field studies and interviews
confirm most hypothesis. Whereas the average
number of alarms recorded is rather low, the peak
values observed during the studies are more
considerably. Situations with twenty and more
alarms leave room for improvement of the relevant
systems. The frequency of alarms depends very
much on the navigational situation.
A further analysis of the results show, that
difficulties in the handling and presentation of
alarms are related, e.g., to the presentation of alarms
and the necessary acknowledgement on various
panels on the bridge, to the lack of a consistent
alarm acknowledgment concept, to alarm
propagation by a single incident, to the lack of
indication of any priority of the alarms, to
difficulties in differentiating the audible alarm
signals and to the fact that in certain navigational
situations too many alarms appear.
Furthermore, interviews with the officers show
preferences:
 for a centralized alarm management display;
 for an indication of alarms according their
priority;
 that the audible alarm signal for certain
functional alarms, e.g., for collision
avoidance, should guide the bridge team
directly to the most concerned navigational
workstation presenting the cause of the
announcement and related information for
decision support.
It can be concluded, that key issues to a
significant improvement of the handling of alarms
and in consequence to an enhanced integrated alarm
management on board are, e.g.:
 the increase of the reliability of sensor data;
 improvement of alarming algorithms, e.g., by
methods to combine data respectively
information of different sensors;
 further development of the human machine
interfaces to more transparent presentation of
alarms;
 integration and connection of all navigational
sensors and systems which will allow to
design a consistent alarm management;
 task orientated integration and presentation of
information on the displays.
5 SUMMARY AND OUTLOOK
Aimed at the improvement of shipborne alarm
management of INS a series of empirical studies
were performed to analyse the present state. For this
purpose real alarm situations on board of vessels
were continuously recorded. Interviews and
questionnaires with experts were used additionally
to collect data about the operational needs of the
navigators.
With respect to kind and frequency of alarms a
great variety was detected. According to the
discussion of the results the strongest correlation is
indicated in respect to the area related navigational
situations. As one of the main reasons it was found,
that the implemented alarm algorithms are fixed,
e.g., for collision warnings, without suitable system
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options to adapt the alarming to the changing
conditions of the different navigational situations.
A future alarm management should harmonize
the operation, handling, distribution and presentation
of alerts. To avoid the uncontrolled increase of
alarms, a set of priorities based on urgency of the
required response is needed to improve the
operator’s situation awareness and his ability to take
effective action. Therefore a new philosophy is
suggested for the prioritization and categorization of
alarms. Alert is defined as umbrella term for the
indication of any abnormal situation with three
different priorities of alerts (IMO, 2006):
 alarm (highest priority) - immediate awareness
and action required;
 warning - awareness of changed condition;
 caution - awareness of condition which does
not warrant an alarm or warning condition, but
still requires attention out of the ordinary
consideration of the situation or of given
information.
The three priorities should be indicated visual
and acoustically in different ways.
To categorize the alerts further, the following
two alert categories are specified.
 navigational alerts - functional indication of
dangerous situation, e.g., collision warning,
depth warning;
 technical alerts - equipment failure or loss.
Basic concepts for improvement of collision
warnings are already available (Baldauf, 2004).
Further research and development is needed and
should be dedicated to apply the concept according
to the functional approach for a new alarm
management.
Finally, a central alert management HMI should
be integrated to support the bridge team in the
immediate identification of any abnormal situation,
including the source and reason for the abnormal
situation and in its decisions for the necessary
actions. The central alert management HMI should
be provided at least at the position from where the
vessel is navigated and fulfil two major functions:
indicating and identifying alerts, allowing the
acknowledgment of alerts by the bridge team.
Primarily, all technical alerts should be
integrated into the alert management, whereas the
navigational (functional) alerts should be primarily
presented at the most concerned navigational
workstation presenting the cause of the alert and
related information for decision support.
The central alert management HMI should then
substitute the alarm announcement (functions) of the
individual equipment to avoid the announcement of
the same alert at two different systems.
ACKNOWLEDGEMENTS
The investigations were part of a project funded by
the German Ministry of Transport, Building, and
Urban Affairs. The authors would like to thank
HAPAG-Lloyd and AIDA Cruises Ltd for their
grateful assistance and all mariners who provided
their knowledge in interviews on board.
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