1 INTRODUCTION

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.

http://www.transnav.eu

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.

2 METHOD

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.

3 SCENARIOS

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