Compared to regular sea-going vessels, DP vessels
have a high risk of getting into accidents due to their
proximity of operations with the installations, even
with a very reliable system. This reliability is achieved
using a significant amount of electronic equipment
due to increased complications in DP vessels. Humans
are at the sharp end, and the chances of making errors
are relatively large. Therefore, the maritime industry
must reduce these risks to make the industry safer and
more efficient.
This paper will review three accidents related to
DP operations. Furthermore, a survey among
experienced DP operators and instructors will be
addressed. Issues regarding human performance,
technological challenges, and organizational handling
will be discussed and compared with the technical
requirements published by Petroleum Safety
Authority of Norway (YA-711) [8] as the codes on
Alerts and Indicators 2009 by IMO only gives basic
provides general design guidance [5].
A triangulated model is used to reflect on the
issues in bridge operations and the alarm handling
process. The three parameters for the triangulated
model are survey results (α), technical requirements
(β), and past (three) accidents (γ) as shown in Figure
Alarm Handling Onboard Vessels Operating in DP Mode
S. Nepal & O.T. Gudmestad
Western Norway University of Applied Sciences, Haugesund, Norway
ABSTRACT: This paper explores concerns regarding the design, implementation, and management of alarms in
DP vessels that, while in operation, need an incredibly high level of accuracy along with high reliability and safe
operations. The Human, Technological, and Organizational factors (HTO) method is primarily used as analysis
tool to find weaknesses in alarm handling during DP operations. The research focuses on results collected from
Dynamic Positioning Operators (DPO) and instructors. Findings from the survey are presented and compared
to the results from past accidents and technical requirements from Petroleum Safety Agency Norway via YA
711. Three accidents from past are referred to picturize the findings from the survey results. Furthermore, the
conclusion is given with recommendations reflecting the findings from the survey. The main findings are an
urgency to establish a centralized marine accident investigation system which enforces learning and
recommendation to make operations safer. In addition, the survey also suggests that prohibition of clients or
limiting their access to the bridge is necessary. Manufacturers could focus on research and development of
alarm prioritization, on structuring and presentation, and profiting by taking feedback from end-users to make
DP operations safer.
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 16
Number 1
March 2022
DOI: 10.12716/1001.16.01.05
Figure 1 Triangulation of parameters.
The cause and effect of inefficiency and confusion
on a bridge will be evaluated with the help of Human,
Technology, and Organizational Analysis [9]. HTO
factors comprise potential in system analysis, design,
and improvement. This method reflects on the
foundation of understanding, improvement, and
development of a properly functioning system [10].
Finally, the results will be presented by discussing
findings from the survey. HTO analysis will reveal the
weaknesses of the current alarm system based on
survey results. The revelation of practical issues
occurs because the survey questionnaire focuses on
practical issues during alarm handling while the
vessel is in a DP mode. Hence, the accidents that have
occurred on DP vessels under the operation in a DP
mode will be used to validate the survey results.
A qualitative approach based on literature review and
survey is adopted as there are little quantitative data
available. An investigative approach is taken in order
to fulfill the purpose of the research [1].
HTO analysis is preferred to analyze the survey
responses due to its simplicity in projection and
understanding of the issues in three vital system
categories. It is unpretentious to segregate any
functioning structure to be implemented in the
human, technology, and organizational division.
Thus, implementing changes or mitigation measures
would be straightforward and effective for impact on
the safety, performance, and efficiency of DP
Operations [10].
In HTO analysis, research is done using the term
humans, pointing towards the operator operating the
DP system, while the organization is the supplier of
the equipment and the shipping company or an
operator/charterer. Finally, the term technology is
aimed to be used for the sensors, equipment, or
instruments, both digital and analog, that aid in the
safe and successful completion of DP operations.
An analysis is done by comparing existing
guidelines (YA 711, [8]) for alarm systems with survey
results. YA 711 has classified alarm design
requirements into the following categories [8].
General requirements
Alarm generation
Alarm structuring
Alarm prioritization
Alarm presentation
Alarm handling
A list of 43 requirements in YA711 [8] for the six
different categories mentioned above is divided into
either human, technology, or organizational
references, as shown in the appendix.
The main concern about alarm systems today is that
offshore vessels are ineffective in resolving issues
regarding alarm systems with advanced technological
tools. It is essential to examine the fundamental issues
hindering offshore vessels’ resilience towards
accidents caused by alarm systems.
Three past accidents are studied; the first is the
collision of PSV Sjoborg with Statfjord A (2019)
published by Equinor [4], the second the collision
between Big Orange XVIII and Ekofisk 2/4-W (2009)
investigated by [2], and the last the collision of
Samundra Suraksha with Mumbai High North
platform (2005) analyzed by [3]. These scenarios will
be used for the validity of survey results.
A collision occurred between Statfjord A and PSV
Sjoborg on 7th June 2019 while loading and
discharging from the platform that was under a
maintenance stop. Sjoborg was operating in load
reduction mode with a preexisting technical issue, i.e.,
10-15% reduction in thruster power. During
operation, power to two of three bow thrusters was
lost. The vessel drifted against the installation,
resulting in severe material damages to the lifeboat
station and monkey island but with no human or
environmental fatalities [4].
It is seen from the accident investigation report by
PSA that underlying causes resulted in insufficient
thruster power [7]. This could be related to the failure
of, or incorrectly installed components, or disruption
from defective components, which led to network
failure in the blackout safety system (“network
storm”). Furthermore, loss of network frequency
measurement on the main switchboard, activation of
the load-reduction mode with restriction of all
thrusters to 10-15 percent of maximum output,
nonconformity between DP commands and automatic
shutdown of thrusters 1 and 3 [4] occurred before the
collision. Due to the overwhelming amount of error
messages and alarms, Dynamic Positioning Operators
(DPOs) could not take proper action to avoid a
collision even with experienced DP operators.
On 8th June 2009, the well simulation vessel Big
Orange XVIII (5000 tonnes) ran into Ekofisk 2/4W. The
ship lost control after entering the 500-meter safety
zone surrounding the Ekofisk complex [2]. The vessel
with a speed of 9.7kn collided heads-on with
approximately 71MJ collision energy with Ekofisk 2/4
X and 2/4 C [6]. Detailed analysis and calculation of
impact loads is drawn in research performed by
Shengming Zang in “The Mechanics of Ship
Collisions” [12]. Due to severe damage to the jacket
installation, ConocoPhillips decided to shut down the
installation and permanently plug the wells. New ice
class vessels that are built with new standards will