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Chapter 6 Situational Awareness for Chief Officer
以下是您提供內容的繁體中文翻譯：
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### 第六章 船長/一副之情境意識 (Situational Awareness for Chief Officer)
#### 第一部分：多佛爾海峽 TSS 多目標碰撞預防準備 (Dover Strait TSS multiple target collision preparedness)
**1999 年貨櫃船與郵輪碰撞事件的迷思 (The Myth of the Container Ship Collision with a Cruiser, 1999)**
##### 碰撞發生與最初的求救呼叫
1999 年 8 月 24 日當地時間約 00:55，多佛爾海峽發生了一起涉及一艘貨櫃船與一艘郵輪的碰撞事故。就在碰撞發生前不久（00:54:37），多佛爾海岸警衛隊在 VHF 頻道 16 錄到一段緊急且未表明身分的通話發聲：「Starboard, starboard, starboard (右滿舵、右滿舵、右滿舵)」。這聲極度慌張的呼叫極可能來自其中一艘船上的工作人員，企圖做最後的掙扎以避免災難發生。
##### 歷史與技術背景
此事故發生於約 26 年前（以 2025 年為基準），正值航海技術變革的關鍵時期。當時，許多新興技術尚未普及：
* 差分全球定位系統（DGPS）仍處於早期應用階段，尚未在各類船舶上廣泛裝設。
* 航行資料記錄器（VDR，即黑盒子）尚未問世，無法記錄關鍵數據以供事後分析。
* 自動雷達測繪板（ARPA）系統大約在 1997 年才開始逐漸普及。
當時的航海業正處於過渡期：從傳統的目視瞭望方法（舊一代航海員所堅持的原則），轉型為使用更先進的 ARPA 系統。儘管技術在演進，ARPA 的性能標準仍緊密結合相對運動速度向量的原則，強調追蹤目標時對於本船相對精準度與可靠性的要求。
##### 相關的 IMO ARPA 性能標準
國際海事組織（IMO）於 1995 年 11 月 23 日通過的第 A.823(19) 號決議案是一項重要的參考依據。該決議詳細規定了「自動雷達測繪板（ARPA）性能標準」，以確保這些系統能提供及時且精確的數據來支援安全航行。具體如下：
| 數據情境 | 相對航向 (度) | 相對速度 (節) | 最近碰撞點距離 CPA (海浬) | 到達最近碰撞點時間 TCPA (分) | 真航向 (度) | 真速度 (節) |
| --- | --- | --- | --- | --- | --- | --- |
| **1** | 3.0 | 0.8 | 0.5 | 1.0 | 7.4 | 1.2 |
| **2** | 2.3 | 0.3-- | 2.8 | 0.8 | — | — |
| **3** | 4.4 | 0.9 | 0.7 | 1.0 | 3.3 | 1.0 |
| **4** | 4.6 | 0.8 | 0.7 | 1.0 | 2.6 | 1.2 |
* **第 3.8.3 條**：ARPA 應在穩定追蹤目標的三分鐘內，呈現該目標的運動數據，並符合以下精準度要求（95% 概率值）：
* **相對航向**：±3° 或更佳。
* **相對速度**：±0.5 節或更佳。
* **最近碰撞點距離 (CPA)**：±0.3 海浬或更佳。
* **到達最近碰撞點時間 (TCPA)**：±0.5 分鐘或更佳。
*(註：原始決議中的具體精準度指標可能包含更多細節；完整參考資料請查閱 IMO 官方文件。)*
##### ARPA 性能標準 (IMO Resolution A.823(19))
IMO 第 A.823(19) 號決議第 3.8.3 條指出：「ARPA 應在穩定追蹤目標的三分鐘內，呈現該目標的運動數據，並符合規定的精準度要求（95% 概率值）。」
該決議包含一份表格，根據目標與本船速度等因素，概述了四種不同情境下的精準度要求：
在相關情境下，前提是必須對目標進行至少三分鐘的穩定追蹤，可接受的最近碰撞點距離（CPA）精準度值（95% 概率）高達 0.7 海浬。若追蹤時間少於三分鐘，ARPA 數據可能會不可靠，應謹慎處理。使用這些數據取決於值班航行員（OOW）的裁量，並伴隨潛在風險。從歷史上看，值班航行員有時會忽視 ARPA 性能標準，未能仔細審查數據中的重大誤差——這與過去在近距離內忽略雷達回波的情況十分相似。
##### 重新審視 1999 年碰撞事故調查
客輪「挪威之夢號 (Norwegian Dream)」與貨櫃船「長彩輪 (Ever Decent)」於 1999 年 8 月 24 日 00:55 在多佛爾海峽接近段發生碰撞。該調查報告發布於 26 年多以前，如今已略顯過時，其結論值得結合後續的技術進步進行重新審視。
自那時以來，海上瞭望流程發生了重大變化，從依賴自動雷達測繪板（ARPA）系統轉變為自動識別系統（AIS）。現在 ARPA 和 AIS 的輸入參數精準得多，特別是在 AIS 中整合了全球定位系統（GPS）數據後——手動輸入航向和航速已不再是標準或可接受的做法。一項關鍵改進是使用對地航速（SOG），它考量了水流和風等外部因素。25 年多以前，不建議將 SOG 用於 ARPA 輸入，因為當時它依賴對船舶過去位置的估算，往往不精確。相比之下，現代的差分 GPS（DGPS）機能提供高精度的 SOG，位置誤差通常僅為 5 到 10 公尺——即使對於靠泊等精細操作也綽綽有餘。
如今，在使用可攜式引水終端（PPU）進行靠泊或避碰時，討論很少再強調對水航速（SOW），因為來自衛星系統的 SOG 已成為可靠的標準。
##### 重新審視調查報告建議
以下各節將簡要回顧 2000 年針對 1999 年「挪威之夢號」與「長彩輪」碰撞事故調查報告中的核心建議。針對每項建議，將先提供原始摘要，隨後給出更新後的建議，該更新考量了過去 25 年以上的技術與程序進展，包括 GPS 整合的改進及駕駛台資源管理（BRM）實務。
###### 給所有船東 (To All Shipowners)
* **關於雷達使用的原始建議：**
當使用一台以上的雷達/自動雷達測繪板（ARPA）時，應僅在一台雷達上進行防碰撞繪算。
* **更新建議：** 利用兩台雷達的優勢互補：一台 10 公分（S 頻段）雷達用於在相對運動餘輝（trails）模式下追蹤小型目標；一台 3 公分（X 頻段）雷達設置於 ARPA 自動捕捉模式，用於快速參考大型船舶。僅依賴單一瞭望方法是不夠的；值班航行員（OOW）應始終保持對小型目標的目視瞭望，若條件允許，應使用第三台雷達或系統來監控較大的船舶。
* **關於速度向量的原始建議：**
若要使用 ARPA 向量判定碰撞風險，應僅使用相對向量；真向量則應用於評估態勢（Aspect）。
* **更新建議：** 對於小型目標，使用相對運動模式下 10 公分雷達上的相對向量。對於 3 公分雷達上的較大目標，採用真運動模式下的真向量來評估態勢與整體交通動態。
* **關於速度輸入的原始建議：**
應提醒所有駕駛台值班人員，雷達/ARPA 上防碰撞繪算的速度輸入必須始終是對水航速（SOW），而非對地航速（SOG）。
* **更新建議：** 為 ARPA 採用來自差分全球定位系統（DGPS）的自動速度輸入，因為它能提供精確的對地航速（SOG）數據，這在現代系統中比手動或以水為基準的輸入更受青睞。
###### 給郵輪公司 (To Cruise Lines)
* **關於雷達瞭望的原始建議：**
碰撞發生時郵輪的值班航行員（OOW）應接受進一步的雷達使用培訓。郵輪公司應確保盡快完成此項培訓，並確保其船隊內的其他駕駛台值班人員完全熟悉他們需要操作的駕駛台設備。
* **更新建議：** 所有值班航行員（OOW）均應研讀相關海事資源（例如本書或同等指南），並接受雷達與電子航海的針對性培訓。傳統的培訓課程可能無法充分涵蓋先進的雷達瞭望知識。
* **關於駕駛台人力配置（Bridge Manning）的原始建議：**
郵輪船長應根據公司程序手冊制定更明確的「船長常規命令（Standing Orders）」，以明確值班航行員（OOW）何時應呼叫駕駛台支援。郵輪公司應確保為其所有船舶制定令人滿意的船長命令。
* **更新建議：** 應評估船員的勝任能力水平，而非僅僅評估 OOW 的人數，並針對不同風險區域（如高交通流量區）的特定需求進行調整。提供詳細的能力要求和指南，而非僅依賴通用的常規命令。
---
### 第六章 船長/一副之情境意識 (Situational Awareness for Chief Officer)
#### 第一部分：多佛爾海峽 TSS 多目標碰撞預防準備 (Dover Strait TSS multiple target collision preparedness)
**1999 年貨櫃船與郵輪碰撞事件的迷思 (The Myth of the Container Ship Collision with a Cruiser, 1999)**
##### 碰撞發生與最初的求救呼叫
1999 年 8 月 24 日當地時間約 00:55，多佛爾海峽發生了一起涉及一艘貨櫃船與一艘郵輪的碰撞事故。就在碰撞發生前不久（00:54:37），多佛爾海岸警衛隊在 VHF 頻道 16 錄到一段緊急且未表明身分的通話發聲：「Starboard, starboard, starboard (右滿舵、右滿舵、右滿舵)」。這聲極度慌張的呼叫極可能來自其中一艘船上的工作人員，企圖做最後的掙扎以避免災難發生。
##### 歷史與技術背景
此事故發生於約 26 年前（以 2025 年為基準），正值航海技術變革的關鍵時期。當時，許多新興技術尚未普及：
* 差分全球定位系統（DGPS）仍處於早期應用階段，尚未在各類船舶上廣泛裝設。
* 航行資料記錄器（VDR，即黑盒子）尚未問世，無法記錄關鍵數據以供事後分析。
* 自動雷達測繪板（ARPA）系統大約在 1997 年才開始逐漸普及。
當時的航海業正處於過渡期：從傳統的目視瞭望方法（舊一代航海員所堅持的原則），轉型為使用更先進的 ARPA 系統。儘管技術在演進，ARPA 的性能標準仍緊密結合相對運動速度向量的原則，強調追蹤目標時對於本船相對精準度與可靠性的要求。
##### 相關的 IMO ARPA 性能標準
國際海事組織（IMO）於 1995 年 11 月 23 日通過的第 A.823(19) 號決議案是一項重要的參考依據。該決議詳細規定了「自動雷達測繪板（ARPA）性能標準」，以確保這些系統能提供及時且精確的數據來支援安全航行。具體如下：
| 數據情境 | 相對航向 (度) | 相對速度 (節) | 最近碰撞點距離 CPA (海浬) | 到達最近碰撞點時間 TCPA (分) | 真航向 (度) | 真速度 (節) |
| --- | --- | --- | --- | --- | --- | --- |
| **1** | 3.0 | 0.8 | 0.5 | 1.0 | 7.4 | 1.2 |
| **2** | 2.3 | 0.3-- | 2.8 | 0.8 | — | — |
| **3** | 4.4 | 0.9 | 0.7 | 1.0 | 3.3 | 1.0 |
| **4** | 4.6 | 0.8 | 0.7 | 1.0 | 2.6 | 1.2 |
* **第 3.8.3 條**：ARPA 應在穩定追蹤目標的三分鐘內，呈現該目標的運動數據，並符合以下精準度要求（95% 概率值）：
* **相對航向**：±3° 或更佳。
* **相對速度**：±0.5 節或更佳。
* **最近碰撞點距離 (CPA)**：±0.3 海浬或更佳。
* **到達最近碰撞點時間 (TCPA)**：±0.5 分鐘或更佳。
*(註：原始決議中的具體精準度指標可能包含更多細節；完整參考資料請查閱 IMO 官方文件。)*
##### ARPA 性能標準 (IMO Resolution A.823(19))
IMO 第 A.823(19) 號決議第 3.8.3 條指出：「ARPA 應在穩定追蹤目標的三分鐘內，呈現該目標的運動數據，並符合規定的精準度要求（95% 概率值）。」
該決議包含一份表格，根據目標與本船速度等因素，概述了四種不同情境下的精準度要求：
在相關情境下，前提是必須對目標進行至少三分鐘的穩定追蹤，可接受的最近碰撞點距離（CPA）精準度值（95% 概率）高達 0.7 海浬。若追蹤時間少於三分鐘，ARPA 數據可能會不可靠，應謹慎處理。使用這些數據取決於值班航行員（OOW）的裁量，並伴隨潛在風險。從歷史上看，值班航行員有時會忽視 ARPA 性能標準，未能仔細審查數據中的重大誤差——這與過去在近距離內忽略雷達回波的情況十分相似。
##### 重新審視 1999 年碰撞事故調查
客輪「挪威之夢號 (Norwegian Dream)」與貨櫃船「長彩輪 (Ever Decent)」於 1999 年 8 月 24 日 00:55 在多佛爾海峽接近段發生碰撞。該調查報告發布於 26 年多以前，如今已略顯過時，其結論值得結合後續的技術進步進行重新審視。
自那時以來，海上瞭望流程發生了重大變化，從依賴自動雷達測繪板（ARPA）系統轉變為自動識別系統（AIS）。現在 ARPA 和 AIS 的輸入參數精準得多，特別是在 AIS 中整合了全球定位系統（GPS）數據後——手動輸入航向和航速已不再是標準或可接受的做法。一項關鍵改進是使用對地航速（SOG），它考量了水流和風等外部因素。25 年多以前，不建議將 SOG 用於 ARPA 輸入，因為當時它依賴對船舶過去位置的估算，往往不精確。相比之下，現代的差分 GPS（DGPS）機能提供高精度的 SOG，位置誤差通常僅為 5 到 10 公尺——即使對於靠泊等精細操作也綽綽有餘。
如今，在使用可攜式引水終端（PPU）進行靠泊或避碰時，討論很少再強調對水航速（SOW），因為來自衛星系統的 SOG 已成為可靠的標準。
##### 重新審視調查報告建議
以下各節將簡要回顧 2000 年針對 1999 年「挪威之夢號」與「長彩輪」碰撞事故調查報告中的核心建議。針對每項建議，將先提供原始摘要，隨後給出更新後的建議，該更新考量了過去 25 年以上的技術與程序進展，包括 GPS 整合的改進及駕駛台資源管理（BRM）實務。
###### 給所有船東 (To All Shipowners)
* **關於雷達使用的原始建議：**
當使用一台以上的雷達/自動雷達測繪板（ARPA）時，應僅在一台雷達上進行防碰撞繪算。
* **更新建議：** 利用兩台雷達的優勢互補：一台 10 公分（S 頻段）雷達用於在相對運動餘輝（trails）模式下追蹤小型目標；一台 3 公分（X 頻段）雷達設置於 ARPA 自動捕捉模式，用於快速參考大型船舶。僅依賴單一瞭望方法是不夠的；值班航行員（OOW）應始終保持對小型目標的目視瞭望，若條件允許，應使用第三台雷達或系統來監控較大的船舶。
* **關於速度向量的原始建議：**
若要使用 ARPA 向量判定碰撞風險，應僅使用相對向量；真向量則應用於評估態勢（Aspect）。
* **更新建議：** 對於小型目標，使用相對運動模式下 10 公分雷達上的相對向量。對於 3 公分雷達上的較大目標，採用真運動模式下的真向量來評估態勢與整體交通動態。
* **關於速度輸入的原始建議：**
應提醒所有駕駛台值班人員，雷達/ARPA 上防碰撞繪算的速度輸入必須始終是對水航速（SOW），而非對地航速（SOG）。
* **更新建議：** 為 ARPA 採用來自差分全球定位系統（DGPS）的自動速度輸入，因為它能提供精確的對地航速（SOG）數據，這在現代系統中比手動或以水為基準的輸入更受青睞。
###### 給郵輪公司 (To Cruise Lines)
* **關於雷達瞭望的原始建議：**
碰撞發生時郵輪的值班航行員（OOW）應接受進一步的雷達使用培訓。郵輪公司應確保盡快完成此項培訓，並確保其船隊內的其他駕駛台值班人員完全熟悉他們需要操作的駕駛台設備。
* **更新建議：** 所有值班航行員（OOW）均應研讀相關海事資源（例如本書或同等指南），並接受雷達與電子航海的針對性培訓。傳統的培訓課程可能無法充分涵蓋先進的雷達瞭望知識。
* **關於駕駛台人力配置（Bridge Manning）的原始建議：**
郵輪船長應根據公司程序手冊制定更明確的「船長常規命令（Standing Orders）」，以明確值班航行員（OOW）何時應呼叫駕駛台支援。郵輪公司應確保為其所有船舶制定令人滿意的船長命令。
* **更新建議：** 應評估船員的勝任能力水平，而非僅僅評估 OOW 的人數，並針對不同風險區域（如高交通流量區）的特定需求進行調整。提供詳細的能力要求和指南，而非僅依賴通用的常規命令。
售價 NT$ 1
Chapter 6- Situational Awareness for Chief Officer
Part one: Dover Strait TSS multiple target collision preparedness
The Myth of the Container Ship Collision with a Cruiser, 1999
####### The Collision and Initial Distress Call
On August 24, 1999, at approximately 00:55 local time, a collision occurred in the Dover Strait,
involving a container ship and a cruiser. Just moments before, at 00:54:37, the Dover Coastguard
recorded an urgent, unidentified transmission on VHF Channel 16: "Starboard, starboard, starboard."
This frantic call likely came from personnel on one of the vessels, a desperate attempt to avert disaster.
Historical and Technological Context
This incident unfolded roughly 26 years ago (as of 2025), during a pivotal period in maritime
navigation. At that time, emerging technologies were not yet prevalent:
The Differential Global Positioning System (DGPS) was still in its early adoption phase and
not widely implemented on vessels.
Voyage Data Recorders (VDRs), which capture critical ship data for post-incident analysis,
were not yet available.
Automatic Radar Plotting Aid (ARPA) systems had only begun to gain traction around 1997.
The maritime industry was in the midst of transitioning from traditional visual lookout methods—
principles upheld by older generations of seafarers—to more advanced ARPA-based systems. Despite
this evolution, the performance standards for ARPAwere closely aligned with the principles of relative
motion speed vector, emphasizing the need for reliability and accuracy in tracking targets relative to the
vessel.
Relevant IMO Standards for ARPA
A significant reference point is the International Maritime Organization (IMO) Resolution A.823(19),
adopted on November 23, 1995. This resolution detailed the "Performance Standards for Automatic
Radar Plotting Aids (ARPAs)," ensuring that these systems could deliver timely and precise data to
support safe navigation. Specifically:
Data
Scenario
Relative
course
(degrees)
Relative
speed
(knots)
CPA
(nautical
miles)
TCPA
(min)
True course
(degrees)
True
speed
(knots)
1 3.0 0.8 0.5 1.0 7.4 1.2
2 2.3 0.3-- 2.8 0.8
3 4.4 0.9 0.7 1.0 3.3 1.0
4 4.6 0.8 0.7 1.0 2.6 1.2
Section 3.8.3: An ARPAshould present, within three minutes of steady-state tracking, the motion of
a target with the following accuracy values (95% probability values):
Relative course: ±3° or better.
Relative speed: ±0.5 knots or better.
Closest Point of Approach (CPA): ±0.3 nautical miles or better.
Time to Closest Point of Approach (TCPA): ±0.5 minutes or better.
(Note: The exact accuracy metrics in the original resolution may include additional details; for a
complete reference, consult the official IMO documentation.)
ARPAPerformance Standards (IMO Resolution A.823(19))
Section 3.8.3 of IMO Resolution A.823(19) states: "An ARPAshould present within three minutes of
steady-state tracking the motion of a target with the following accuracy values (95% probability
values)."
The resolution includes a table outlining accuracy requirements across four scenarios, based on
factors such as target and own-ship speeds:
The acceptable Closest Point of Approach (CPA) accuracy value (95% probability) is up to 0.7
nautical miles in relevant scenarios, assuming at least three minutes of steady-state target tracking. If
the tracking time is less than three minutes, ARPAdata may be unreliable and should be treated with
caution. The use of this data falls under the Officer of the Watch's (OOW) discretion and involves
inherent risks. Historically, OOWs have sometimes overlooked ARPAperformance standards, failing to
scrutinize significant errors in data—similar to how radar echoes were often disregarded at close
range.
Re-Examining the 1999 Collision Investigation
The collision between the passenger vessel Norwegian Dream and the container ship Ever Decent
occurred in the approaches to the Dover Strait at 00:55 on August 24, 1999. The investigation report,
issued over 26 years ago, is now somewhat outdated, and its conclusions merit re-examination in light
of subsequent technological advancements.
Since that time, maritime lookout processes have evolved significantly, shifting from reliance on
Automatic Radar Plotting Aid (ARPA) systems to the Automatic Identification System (AIS). The input
parameters for ARPAand AISare now far more accurate, particularly with the integration of Global
Positioning System (GPS) data in AIS—manual entry of course and speed is no longer standard or
acceptable practice. A key improvement is the use of Speed Over Ground (SOG), which accounts for
external factors such as currents and wind. Over 25 years ago, SOG was not recommended for
ARPAinputs, as it relied on estimates from past ship positions, often imprecise. In contrast, modern
Differential GPS (DGPS) provides SOG with high accuracy, typically featuring position errors of only 5
to 10 meters—adequate even for precise operations like berthing.
Today, discussions seldom emphasize Speed Over Water (SOW) when utilizing tools like Portable
Pilot Units (PPUs) for docking or collision avoidance, as SOG from satellite-based systems has
become the reliable standard.
Review of Report Recommendations
The following sections will briefly review the key recommendations from the 2000 investigation
report into the 1999 collision between the Norwegian Dream and Ever Decent. For each
recommendation, the original summary will be provided, followed by an updated recommendation that
considers technological and procedural advancements over the past 25+ years, including
improvements in GPS integration and bridge resource management practices.
To All Shipowners
Original Recommendation on radar usage:
When using more than one radar/Automatic Radar Plotting Aid (ARPA), an anti-collision plot
should be maintained on only one.
Updated Recommendation: Utilize two radars to leverage their complementary strengths: a 10-cm
(S-band) radar for tracking small targets in relative motion trails mode, and a 3-cm (X-band) radar in
ARPAauto-acquisition mode for quick reference of larger vessels. Relying solely on one lookout
method is insufficient; the Officer of the Watch (OOW) should always include visual lookout for small
targets and, if available, a third radar or system for monitoring larger vessels.
Original Recommendation on speed vector:
To determine the risk of collision using ARPAvectors, only relative vectors should be used. True
vectors should be utilized to assess aspect.
Updated Recommendation: For small targets, use the relative vector on a 10-cm radar in relative
motion mode. For larger targets on a 3-cm radar, employ the true vector in true motion mode to
evaluate aspectand overall traffic dynamics.
Original Recommendation on speed input:
All bridge watchkeepers should be reminded that the speed input for an anti-collision plot on
radar/ARPAshould always be speed through the water, not speed over the ground.
Updated Recommendation: Utilize auto-speed input from Differential Global Positioning System
(DGPS) for ARPA, as it provides accurate Speed Over Ground (SOG) data, which is now preferred
over manual or water-referenced inputs in modern systems.
To Cruise Lines
Original Recommendation on radar lookout:
The OOWof the cruiser at the time of the collision should undertake further training in radar usage.
Cruise lines should ensure that this is completed as soon as possible and that other bridge
watchkeepers within their fleet are fully familiar with the bridge equipment they will need to operate.
Updated Recommendation: All OOWs should engage with relevant maritime resources (such as
this book or equivalent guides) and undergo targeted training in radar and electronic navigation.
Traditional training programs may not adequately cover advanced radar lookout knowledge.
Original Recommendation on Bridge Manning:
The Master of the cruiser should establish more explicit Standing Orders in accordance with the
Company Procedure Manual to clarify when the Officer of the Watch (OOW) should call for assistance
on the bridge. Cruise lines should ensure that satisfactory master’s orders are in place for all of their
ships.
Updated Recommendation: Assess crew competence levels rather than just the number of OOWs,
and tailor responses to the specific demands of varying risk areas (e.g., high-traffic zones). Provide
detailed competence requirements and guidelines instead of relying solely on generic standing orders.
Part one: Dover Strait TSS multiple target collision preparedness
The Myth of the Container Ship Collision with a Cruiser, 1999
####### The Collision and Initial Distress Call
On August 24, 1999, at approximately 00:55 local time, a collision occurred in the Dover Strait,
involving a container ship and a cruiser. Just moments before, at 00:54:37, the Dover Coastguard
recorded an urgent, unidentified transmission on VHF Channel 16: "Starboard, starboard, starboard."
This frantic call likely came from personnel on one of the vessels, a desperate attempt to avert disaster.
Historical and Technological Context
This incident unfolded roughly 26 years ago (as of 2025), during a pivotal period in maritime
navigation. At that time, emerging technologies were not yet prevalent:
The Differential Global Positioning System (DGPS) was still in its early adoption phase and
not widely implemented on vessels.
Voyage Data Recorders (VDRs), which capture critical ship data for post-incident analysis,
were not yet available.
Automatic Radar Plotting Aid (ARPA) systems had only begun to gain traction around 1997.
The maritime industry was in the midst of transitioning from traditional visual lookout methods—
principles upheld by older generations of seafarers—to more advanced ARPA-based systems. Despite
this evolution, the performance standards for ARPAwere closely aligned with the principles of relative
motion speed vector, emphasizing the need for reliability and accuracy in tracking targets relative to the
vessel.
Relevant IMO Standards for ARPA
A significant reference point is the International Maritime Organization (IMO) Resolution A.823(19),
adopted on November 23, 1995. This resolution detailed the "Performance Standards for Automatic
Radar Plotting Aids (ARPAs)," ensuring that these systems could deliver timely and precise data to
support safe navigation. Specifically:
Data
Scenario
Relative
course
(degrees)
Relative
speed
(knots)
CPA
(nautical
miles)
TCPA
(min)
True course
(degrees)
True
speed
(knots)
1 3.0 0.8 0.5 1.0 7.4 1.2
2 2.3 0.3-- 2.8 0.8
3 4.4 0.9 0.7 1.0 3.3 1.0
4 4.6 0.8 0.7 1.0 2.6 1.2
Section 3.8.3: An ARPAshould present, within three minutes of steady-state tracking, the motion of
a target with the following accuracy values (95% probability values):
Relative course: ±3° or better.
Relative speed: ±0.5 knots or better.
Closest Point of Approach (CPA): ±0.3 nautical miles or better.
Time to Closest Point of Approach (TCPA): ±0.5 minutes or better.
(Note: The exact accuracy metrics in the original resolution may include additional details; for a
complete reference, consult the official IMO documentation.)
ARPAPerformance Standards (IMO Resolution A.823(19))
Section 3.8.3 of IMO Resolution A.823(19) states: "An ARPAshould present within three minutes of
steady-state tracking the motion of a target with the following accuracy values (95% probability
values)."
The resolution includes a table outlining accuracy requirements across four scenarios, based on
factors such as target and own-ship speeds:
The acceptable Closest Point of Approach (CPA) accuracy value (95% probability) is up to 0.7
nautical miles in relevant scenarios, assuming at least three minutes of steady-state target tracking. If
the tracking time is less than three minutes, ARPAdata may be unreliable and should be treated with
caution. The use of this data falls under the Officer of the Watch's (OOW) discretion and involves
inherent risks. Historically, OOWs have sometimes overlooked ARPAperformance standards, failing to
scrutinize significant errors in data—similar to how radar echoes were often disregarded at close
range.
Re-Examining the 1999 Collision Investigation
The collision between the passenger vessel Norwegian Dream and the container ship Ever Decent
occurred in the approaches to the Dover Strait at 00:55 on August 24, 1999. The investigation report,
issued over 26 years ago, is now somewhat outdated, and its conclusions merit re-examination in light
of subsequent technological advancements.
Since that time, maritime lookout processes have evolved significantly, shifting from reliance on
Automatic Radar Plotting Aid (ARPA) systems to the Automatic Identification System (AIS). The input
parameters for ARPAand AISare now far more accurate, particularly with the integration of Global
Positioning System (GPS) data in AIS—manual entry of course and speed is no longer standard or
acceptable practice. A key improvement is the use of Speed Over Ground (SOG), which accounts for
external factors such as currents and wind. Over 25 years ago, SOG was not recommended for
ARPAinputs, as it relied on estimates from past ship positions, often imprecise. In contrast, modern
Differential GPS (DGPS) provides SOG with high accuracy, typically featuring position errors of only 5
to 10 meters—adequate even for precise operations like berthing.
Today, discussions seldom emphasize Speed Over Water (SOW) when utilizing tools like Portable
Pilot Units (PPUs) for docking or collision avoidance, as SOG from satellite-based systems has
become the reliable standard.
Review of Report Recommendations
The following sections will briefly review the key recommendations from the 2000 investigation
report into the 1999 collision between the Norwegian Dream and Ever Decent. For each
recommendation, the original summary will be provided, followed by an updated recommendation that
considers technological and procedural advancements over the past 25+ years, including
improvements in GPS integration and bridge resource management practices.
To All Shipowners
Original Recommendation on radar usage:
When using more than one radar/Automatic Radar Plotting Aid (ARPA), an anti-collision plot
should be maintained on only one.
Updated Recommendation: Utilize two radars to leverage their complementary strengths: a 10-cm
(S-band) radar for tracking small targets in relative motion trails mode, and a 3-cm (X-band) radar in
ARPAauto-acquisition mode for quick reference of larger vessels. Relying solely on one lookout
method is insufficient; the Officer of the Watch (OOW) should always include visual lookout for small
targets and, if available, a third radar or system for monitoring larger vessels.
Original Recommendation on speed vector:
To determine the risk of collision using ARPAvectors, only relative vectors should be used. True
vectors should be utilized to assess aspect.
Updated Recommendation: For small targets, use the relative vector on a 10-cm radar in relative
motion mode. For larger targets on a 3-cm radar, employ the true vector in true motion mode to
evaluate aspectand overall traffic dynamics.
Original Recommendation on speed input:
All bridge watchkeepers should be reminded that the speed input for an anti-collision plot on
radar/ARPAshould always be speed through the water, not speed over the ground.
Updated Recommendation: Utilize auto-speed input from Differential Global Positioning System
(DGPS) for ARPA, as it provides accurate Speed Over Ground (SOG) data, which is now preferred
over manual or water-referenced inputs in modern systems.
To Cruise Lines
Original Recommendation on radar lookout:
The OOWof the cruiser at the time of the collision should undertake further training in radar usage.
Cruise lines should ensure that this is completed as soon as possible and that other bridge
watchkeepers within their fleet are fully familiar with the bridge equipment they will need to operate.
Updated Recommendation: All OOWs should engage with relevant maritime resources (such as
this book or equivalent guides) and undergo targeted training in radar and electronic navigation.
Traditional training programs may not adequately cover advanced radar lookout knowledge.
Original Recommendation on Bridge Manning:
The Master of the cruiser should establish more explicit Standing Orders in accordance with the
Company Procedure Manual to clarify when the Officer of the Watch (OOW) should call for assistance
on the bridge. Cruise lines should ensure that satisfactory master’s orders are in place for all of their
ships.
Updated Recommendation: Assess crew competence levels rather than just the number of OOWs,
and tailor responses to the specific demands of varying risk areas (e.g., high-traffic zones). Provide
detailed competence requirements and guidelines instead of relying solely on generic standing orders.
