The ship’s bridge is where SOLAS Chapter V Regulation 15 becomes architecture. Every workstation, every sensor feed, and every alarm path must satisfy the human-element principles that the IMO has been codifying since the 1990s: minimise distraction, maintain sightlines from the conning position, and ensure the officer of the watch can keep watch continuously. That regulation was adopted alongside Regulation 19’s carriage schedule and Regulation 22’s visibility geometry, the three together forming a coherent system for what equipment must be aboard, how it must perform, and how it must be presented to the navigator.
The carriage requirements in SOLAS V Regulation 19 now span more than a dozen equipment categories, each referencing a dedicated IMO performance standard. The radar standard is MSC.192(79). The ECDIS standard is MSC.232(82). The INS standard is MSC.252(83). The alert management standard is MSC.302(87). The VDR standard is MSC.333(90). Understanding these instruments is the foundation for understanding how a modern bridge functions and what the regulations actually require.
SOLAS Chapter V: the regulatory architecture
SOLAS Chapter V addresses safety of navigation across 35 regulations. The three that govern bridge equipment most directly are Regulations 15, 18, and 19, with Regulation 22 adding the visibility geometry constraint.
Regulation 15 (bridge design) states that the design of navigational systems and equipment must take into account the human-element guidelines in IMO Resolution A.947(23) and its successor MSC-MEPC.7/Circ.6. The requirement is functional: equipment must be positioned so the OOW can keep watch without obstruction, and alarm systems must not overload the watchkeeper. This regulation gives flag states the authority to reject an installation even when the equipment individually meets its type-approval standard, if the installation itself creates a human-element hazard.
Regulation 18 (approval of equipment) requires type approval by the flag administration to the applicable IMO performance standard. No ship can comply with Regulation 19’s carriage requirements using an unapproved item. Where no IMO performance standard exists, the flag state may approve to a national standard providing equivalent performance. This provision has been invoked for several newer technologies (solid-state radar, broadband satellite terminals) where IMO performance standards lagged the technology.
Regulation 19 (carriage requirements) is the detailed schedule, with requirements tiered by gross tonnage and, in several categories, differentiated between ships constructed before or after specified dates. The table below summarises the principal carriage triggers.
| Equipment | SOLAS V Reg 19 trigger | Ships excluded |
|---|---|---|
| Magnetic compass | All ships | None |
| Gyrocompass with repeaters | Ships of 500 GT and upward; ships of 150 GT and upward (all passenger ships) | Ships under 150 GT |
| Echo sounder | Ships of 300 GT and upward; all passenger ships | Ships under 300 GT |
| Radar (one) | Ships of 300 GT and upward; all passenger ships | Under 300 GT |
| Second independent radar | Ships of 3,000 GT and upward | Under 3,000 GT |
| ARPA | Ships of 10,000 GT and upward | Under 10,000 GT |
| ATA (automatic tracking) | Ships of 3,000 GT and upward, under 10,000 GT | Under 3,000 GT; over 10,000 GT already need ARPA |
| AIS Class A | Ships of 300 GT and upward on international voyages; all passenger ships | Under 300 GT on domestic; fishing vessels |
| VDR | Passenger ships; cargo ships of 3,000 GT and upward built on or after 1 July 2002 | Under 3,000 GT; older cargo ships (S-VDR required for some) |
| S-VDR | Existing cargo ships of 3,000 GT and upward built before 1 July 2002 | Under 3,000 GT |
| BNWAS | All ships of 150 GT and upward on international voyages (phased from 2011) | Under 150 GT |
| ECDIS | Phased mandatory carriage: all new ships from 2012-2014; all existing ships by 2018 (see table below) | Ships in domestic trade with flag-state exemption |
| LRIT | Cargo ships of 300 GT and upward; passenger ships on international voyages | Domestic-trade exemptions apply |
| Speed log | Ships of 300 GT and upward | Under 300 GT |
Regulation 22 (navigation-bridge visibility) specifies that the field of view from the conning position must provide a 225-degree arc from right ahead to 22.5 degrees abaft the beam on each side, with no dead sector exceeding 10 degrees within the 10-degree-to-10-degree arc directly ahead. These geometry constraints directly shape the bridge layout and the placement of consoles, masts, and funnels on every new building.
ECDIS mandatory carriage: the phase-in schedule
ECDIS carriage became mandatory under SOLAS V Regulation 19 through amendments adopted at MSC 85 in 2008 (MSC.282(86)). The phase-in ran in two streams, new builds and existing ships, and across passenger, tanker, and cargo ship categories.
| Ship category | New builds from | Existing ships by |
|---|---|---|
| Passenger ships above 500 GT | 1 July 2012 | 1 July 2014 |
| Tankers above 3,000 GT | 1 July 2012 | 1 July 2015 |
| Cargo ships above 10,000 GT | 1 July 2013 | 1 July 2016 |
| Cargo ships 3,000-10,000 GT | 1 July 2014 | 1 July 2017 |
| Cargo ships 50,000 GT and above | 1 July 2013 | 1 July 2016 |
A SOLAS-compliant ECDIS must use Electronic Navigational Charts (ENCs) conforming to IHO S-57 transfer standard and S-52 presentation library. Raster Navigation Charts (RNCs), which are scanned paper charts, do not satisfy the carriage requirement, though they remain a permitted backup source. The backup arrangement itself is a SOLAS requirement: either a second independent ECDIS or an up-to-date portfolio of paper charts adequate for the voyage.
The ECDIS performance standard, IMO MSC.232(82), specifies the chart data the system must support, the accuracy of position display, the route monitoring and safety depth/height alarm functions, the sensor input interfaces, and the voyage data recording outputs. IEC 61174 provides the detailed type-test procedures against which type approval is issued.
Core navigation equipment
Gyrocompass and magnetic compass
Every ship of 500 GT and above must carry a gyrocompass capable of determining and displaying the ship’s heading in degrees true. The IMO performance standard for gyrocompasses is Resolution A.424(XI), amplified by the bridge-equipment standard MSC-Circ.982 for installation. A gyrocompass must settle to within 1 degree of true north under normal ship manoeuvring and maintain that accuracy within plus or minus 0.5 degrees under steady-state conditions at latitudes up to 70 degrees.
Modern gyrocompass installations use one of three sensing technologies: the traditional spinning-rotor mechanical gyroscope (which can take 4 to 6 hours to settle after power-up), the fibre-optic gyroscope (FOG, settling in 30 minutes or less), or the ring-laser gyroscope (RLG, similar settling time to FOG). For INS-certified systems, the gyrocompass feeds the heading bus that every other task station reads: ECDIS display orientation, radar stabilisation mode, autopilot reference, and AIS transmitted heading all come from this single data source, validated against the second gyro where fitted.
The magnetic compass remains SOLAS-mandatory on every ship regardless of size, precisely because it requires no electrical power. A ship experiencing a complete electrical failure retains heading reference from the magnetic compass. Compass deviation correction uses a binnacle assembly with heeling-error correctors, Flinders bar, and soft-iron quadrantal spheres. Qualified compass adjusters must re-examine the deviation table after any significant structural modification to the ship or installation of large steel masses near the bridge. The nav-compass-deviation calculator allows officers to compute the corrected compass course for a given deviation table and magnetic variation. The sun amplitude compass check calculator cross-checks deviation using observed bearing of the sun at rising or setting.
Radar and ARPA
The radar performance standard for marine use is IMO MSC.192(79), adopted in 2004, replacing the previous A.477(XII). MSC.192(79) introduced the IEC 62388 series as the type-test standard and mandated minimum detection ranges, bearing and range accuracy, rain and sea clutter controls, and ARPA performance requirements in a single coherent instrument.
MSC.192(79) specifies that an X-band (9 GHz) radar must detect a target with a radar cross-section of 10 m² at 6 nautical miles in calm conditions, and that an S-band (3 GHz) radar must detect the same target at 10 nautical miles. Range accuracy must be within 1% of the range scale in use or 30 metres, whichever is greater. Bearing accuracy must be within 1 degree. These figures apply to type-tested equipment; installed performance varies with antenna height, sea state, and interference environment.
ARPA (Automatic Radar Plotting Aid) is mandatory on ships of 10,000 GT and above under SOLAS V Regulation 19.2.3. It must automatically acquire and track at least 20 targets simultaneously, compute each target’s closest point of approach (CPA) and time to CPA (TCPA) using the target’s motion over a tracking period of 1 to 3 minutes, and display a trial manoeuvre capability allowing the OOW to evaluate the collision-avoidance effect of a proposed course or speed change before committing. The nav-cpa-tcpa calculator provides the manual computation against which ARPA output can be cross-checked.
Ships of 3,000 to 10,000 GT must carry automatic tracking aid (ATA), which provides ARPA-equivalent tracking capability but may have a lower simultaneous target count (ten, rather than twenty). Ships of 500 to 3,000 GT must carry electronic plotting aid (EPA), a basic manual-assisted plotting function.
The parallel indexing technique, which uses the radar’s variable range marker and electronic bearing line to maintain a fixed clearance from a coastal feature, is a key procedural complement to ARPA and does not require AIS correlation. The nav-parallel-indexing calculator supports passage planning for this technique.
ECDIS and Electronic Navigational Charts
ECDIS under MSC.232(82) is defined as a navigation information system that, with adequate back-up arrangements, can be accepted as complying with the up-to-date chart requirements of SOLAS V Regulation 19. Four mandatory functions define the standard: continuous chart display with vessel position, route monitoring with automatic alarms when the vessel approaches a safety contour or waypoint boundary, look-ahead sensing of chart objects inside the safety frame, and voyage data recording.
The ENC data model is IHO S-57. An ENC cell covers a specific sea area at one of six usage bands (overview at 1:3,500,000 through berthing at 1:2,500 and larger). The ECDIS must load, merge, and display cells from multiple bands simultaneously, resolving priority according to S-52 presentation library rules. Cell updates arrive as incremental ER (exchange reference) files from the ENC distributor, and the ECDIS must apply them and log the update history as part of its voyage record.
The safety depth setting (also called CATZOC-dependent safety contour) is the single most safety-critical operator input on an ECDIS. Setting it too deep wastes sea room; setting it too shallow allows the vessel to sail across charted dangers without alarm. MSC.232(82) requires that the system alarm when the vessel’s tracked position crosses the selected safety contour and that the safety contour be displayed in a visually distinct colour. STCW 2010 and the associated STCW.7/Circ.6 from 2017 require that deck officers operating ECDIS as the primary means of navigation hold generic ECDIS training (type-independent, per IMO Model Course 1.27) plus type-specific familiarisation for each make and model of ECDIS installed on the vessel.
A backup arrangement is mandatory: a second ECDIS on a separate power feed and computer, or a current paper chart portfolio adequate for the entire voyage. The IMO Position Statement MSC.1/Circ.1533 (2016) clarified that a second ECDIS satisfies the backup requirement only if it operates independently of the first (separate processor, separate power source, separate sensors).
AIS Class A
The AIS Class A performance standard is IMO Resolution MSC.74(69) Annex 3, implemented through ITU-R M.1371, which is now at edition 5 (2014). AIS Class A is mandatory on ships of 300 GT and above on international voyages and on all passenger ships irrespective of size under SOLAS V Regulation 19.2.
AIS Class A operates on two dedicated VHF channels: AIS 1 at 161.975 MHz and AIS 2 at 162.025 MHz, using self-organising time division multiple access (SOTDMA). The unit transmits position reports at intervals from 2 seconds (for ships at speed above 23 knots underway) to 3 minutes (for ships at anchor). The transmitted data set includes the MMSI, call sign, ship name, IMO number, type of ship, dimensions, GNSS antenna position relative to the hull, navigational status, SOG, COG, true heading, ROT, and the ETA and destination entered by the crew.
AIS data received from surrounding vessels feeds both the radar display (as targets overlaid on the radar picture) and the ECDIS (as AIS target symbols on the chart). ARPA tracks can be correlated with AIS targets to produce fused targets with both radar-measured kinematics and AIS-reported identity. The ais-class-a-carriage calculator checks whether a given ship type and GT triggers the Class A carriage obligation. Related wiki treatment is at AIS and ECDIS.
Echo sounder, speed log, and GNSS
SOLAS V Regulation 19 requires an echo sounder on ships of 300 GT and above. The performance standard, resolution A.224(VII) as amended, specifies a minimum depth range of 2 metres to 200 metres, accuracy within 1.5% at frequencies between 50 kHz and 200 kHz, and a clear audio or visual indication of sounding. A dual-frequency transducer (50 kHz and 200 kHz) is common: 200 kHz gives sharper resolution in shallow water; 50 kHz penetrates deeper into soft bottoms.
The speed log (or Doppler velocity log) must be fitted on ships of 300 GT and above per SOLAS V Regulation 19.2.1.6. The standard is A.824(19) for electromagnetic logs. A speed through water value is needed for leeway and set-and-drift calculations; a Doppler bottom-track value (available from acoustic logs in shallow water) gives speed over ground directly from the transducer rather than from GNSS.
GNSS (Global Navigation Satellite System) is not listed as a standalone SOLAS carriage requirement but is instead mandated indirectly: ECDIS, AIS, VDR, and LRIT all require a GNSS position input, making a GNSS receiver an implied necessity on any ship carrying those items. The performance standard for GNSS receivers is Resolution A.819(19). Differential GNSS (DGNSS) providing accuracy below 10 metres is available from shore-based beacon networks (IALA) and, in some regions, from SBAS systems such as EGNOS, WAAS, and the Indian GAGAN. The nav-dead-reckoning-error calculator quantifies the accumulated position error when GNSS is unavailable and the vessel relies on DR from gyrocompass, speed log, and known current.
Voyage Data Recorder
The VDR performance standard was substantially revised by IMO MSC.333(90), adopted in 2012, which replaced the earlier MSC.163(78). MSC.333(90) extended the mandatory recording duration to 48 hours (from 12 hours in the earlier standard) for new installations, added requirements for the annual performance test, and clarified the data elements required. Full treatment is at the companion article voyage-data-recorder-vdr; the key structural points for integration with bridge equipment are below.
The VDR must record, continuously and in real time: date and time, ship’s position (GNSS), speed, heading, bridge audio (multiple microphones covering the conning position, chart table, and port and starboard bridge wings), VHF communications audio, radar video (at least one complete antenna revolution per scan cycle from each fitted radar), AIS data, ECDIS display state, main alarms, rudder order and response, engine order and response, hull openings (where monitored), watertight and fire door status (where monitored), and wind speed and direction.
The crash-protected capsule, which must float free on immersion, must survive fire (1,300°C for 60 minutes), impact (1,000 g for 6 milliseconds), crush (6.25 tonnes), and deep water immersion (3,000 metres for 10 minutes). These figures are the IEC 61996-1 performance requirements against which type approval is tested.
The simplified VDR (S-VDR) per MSC.214(81) has a reduced data set: the capsule must record date, time, position, speed, heading, and bridge audio. Radar video is not required. The S-VDR applies to existing cargo ships of 3,000 to under 20,000 GT not required to carry a full VDR.
The VDR annual performance test, which must be conducted by an approved service supplier and recorded in a certificate filed with the flag state, verifies that data from every mandatory channel is reaching the capsule at the required quality. The test report must be kept on board. A VDR that has not been tested in the prior 12 months is, as a matter of flag-state inspection practice, treated as non-functional for the purposes of PSC.
BNWAS
The BNWAS performance standard is MSC.128(75), which defines a three-stage alarm escalation: dormancy period (3 to 12 minutes, master-set), first alarm to an annunciator on the bridge if unacknowledged within a set period after the dormancy expires, then escalation to the master’s cabin, then to other officers’ cabins. MSC.128(75) requires that the BNWAS record all activation and alarm events with timestamp in a non-volatile log accessible to inspectors but not to the crew. The carriage requirement under SOLAS V Regulation 19.2.2.3 applies to all ships of 150 GT and above on international voyages, phased in between 2011 and 2013 depending on ship type and size.
Integrated Navigation System (INS): MSC.252(83)
IMO Resolution MSC.252(83) defines the INS as a combination of systems and equipment that are interconnected and interdependent to support the performance of navigational tasks on a ship. The distinction from an IBS is architectural: an INS is specifically navigation-focused, defined by the task stations it supports rather than by the physical workstation layout.
MSC.252(83) identifies five navigational task areas that an INS may cover, any or all of which can be included:
- Route planning
- Route monitoring
- Collision avoidance
- Navigation in special areas (pilotage waters, ice, traffic separation schemes)
- Navigation information display
For each task area where INS integration is claimed, the equipment and data interfaces must meet the performance standard for the task. For route monitoring, the INS must integrate ECDIS display with the active route, with look-ahead alarming, and with the GNSS position feed validated to the accuracy specified in MSC.232(82). For collision avoidance, the INS must integrate radar/ARPA targets and AIS targets with the ECDIS chart display and provide trial manoeuvre capability referenced to the actual chart.
The data interface standards are critical to INS operation. IEC 61162-1 specifies the NMEA 0183 serial data format used by legacy sensor outputs. IEC 61162-2 covers high-speed NMEA 0183 for heading and position sensors with higher update rates. IEC 61162-450 specifies the NMEA 2000 / IEC 61162 Ethernet network (also called IEC 61162-450) for INS-class integration, where sensor data is published on a LAN backbone rather than point-to-point serial links. The presentation standard for display devices within an INS is IEC 62288, which governs luminance, resolution, colour coding, symbol sets, and legibility under bridge lighting conditions from full daylight to full darkness.
The alert management system: MSC.302(87)
Before MSC.302(87) was adopted in 2010, each bridge equipment item presented alarms through its own panel and display. A bridge with separate alarm panels for the ECDIS, each radar, the GMDSS radio, the autopilot, the VDR, the engine monitoring system, and the ship’s HVAC could present dozens of simultaneous alert panels to the OOW. The collision investigations in the 2000s repeatedly identified alarm overload as a contributing factor.
MSC.302(87), the Performance Standards for Bridge Alert Management, requires that all alert-generating systems on the bridge funnel alerts through a centralised alert management (CAM) system. Alerts are categorised as: alarm (immediate action required to prevent hazard to the ship), warning (attention and subsequent action required), or caution (awareness that action may be required). The CAM display shows all active alerts sorted by category and time, with each alert identified by source system, alert text, and status (unacknowledged, acknowledged, silenced). The officer can transfer alert responsibility from one workstation to another without clearing the alert, which matters when the conning officer moves to the chart table.
IEC 62923-1 and IEC 62923-2 are the detailed technical standards for BAM system hardware and software. IEC 62923-1 covers the requirements for the alert distribution unit and the CAM HMI; IEC 62923-2 covers the requirements for alert-generating equipment to publish alerts in the standard format. Equipment type-approved to IEC 62923-2 is described as “BAM-compatible.”
Conning display and INS task stations
The conning display is the single station showing all parameters needed to control the ship’s motion: heading (gyro and magnetic), ROT, speed through water, speed over ground, wind speed and direction, thruster status, rudder angle, engine RPM and mode, and GNSS position with accuracy indicator. On a well-designed INS, the conning display draws from the validated sensor bus rather than directly from individual sensors, so a sensor failure shows a flagged value on the conning display rather than silently propagating an error.
IMO MSC-Circ.982 (Guidelines on ergonomic criteria for bridge equipment) recommends a workstation layout with a maximum 250 mm of monitor surface at table-top height to avoid blocking forward visibility, and specifies minimum luminance and contrast ratios for displays at every bridge-lighting condition from 10,000 lux sunlight to 1 lux night. IEC 62288 implements these ergonomic criteria in a testable form that type approval houses verify.
Heading and Track Control Systems
The autopilot, properly called a heading control system (HCS) when it maintains a set heading, or a track control system (TCS) when it follows an ECDIS route, is governed by ISO 11674 (heading control) and IEC 62065 (track control). The ISO 11674 standard specifies heading-keeping accuracy, rudder activity limits to avoid excessive wear, and mode-change alarm requirements. IEC 62065 adds the track-keeping accuracy requirements: the system must maintain cross-track error within defined limits that tighten as the vessel approaches waypoint alteration points.
A TCS installation must receive its waypoint sequence from the active ECDIS route, and the cross-track error must be displayed on both the TCS panel and the ECDIS. This integration means that a TCS failure alarm and an ECDIS off-track alarm can arise from the same event; the CAM system per MSC.302(87) must present both without duplication. SOLAS V Regulation 19 does not mandate TCS carriage; it mandates heading control. TCS is fitted voluntarily on many large deep-sea vessels for crew workload reduction.
The distinction between automatic course change at a waypoint (a TCS function) and manual helm intervention is operationally important. At no point during TCS operation is the officer of the watch relieved of the duty to maintain a lookout and to take manual control if the automated system’s actions would lead to danger. SOLAS V Regulation 34-1 (as amended) requires that ships in MASS (Maritime Autonomous Surface Ship) trials notify the flag state and obtain specific permission, indicating that full autopilot sovereignty remains a regulatory work in progress even for trials.
GMDSS at the bridge
The Global Maritime Distress and Safety System does not sit in the SOLAS V regulatory scheme; its carriage requirements are in SOLAS Chapter IV. But all GMDSS equipment is bridge-mounted (or bridge-adjacent for EPIRB) and is therefore part of the integrated bridge architecture.
GMDSS sea area A1 requires a VHF radio with DSC on channel 70, a VHF handheld set, and NAVTEX. Sea area A2 adds an MF radio with DSC on 2187.5 kHz. Sea area A3, which covers most of the world’s ocean trading routes outside polar regions, adds either an Inmarsat-C terminal or an HF radio. Sea area A4 covers the polar regions above and below Inmarsat coverage and requires HF radio.
The NAVTEX receiver (518 kHz international; 490 kHz national; 4209.5 kHz for some extended range services) provides automatic reception of navigation warnings, meteorological forecasts, and other maritime safety information broadcasts. The NAVTEX message database, which builds over hours of reception, is a mandatory voyage resource: the deck officer planning a coastal passage must check the NAVTEX for T-messages (navigation warnings) affecting the planned track.
The EPIRB must be capable of floating free on immersion and activating automatically. It transmits on 406 MHz to the COSPAS-SARSAT satellite system and on 121.5 MHz as a homing frequency for SAR aircraft. The battery expiry date and the hydrostatic release unit (HRU) expiry date are subject to annual inspection; the EPIRB must be registered with the national MMSI authority and that registration must match the ship’s current flag, name, and contact details. The system-epirb-406-mhz-float-free article treats the AIS SART, the radar SART, and the EPIRB together as the survival craft distress signalling suite. The full GMDSS framework is at SOLAS Chapter IV: Radiocommunications GMDSS, and the GMDSS sea area carriage check is in the GMDSS sea area coverage calculator.
The Integrated Bridge System concept: MSC.64(67) Annex 3
The term “Integrated Bridge System” predates INS in the IMO instruments. IMO Resolution MSC.64(67) Annex 3 (1996) defined an IBS as a combination of systems that are interconnected and interdependent to permit centralised access to sensor information or command/control from workstations. The IBS concept is broader than INS: it may include cargo control, damage control monitoring, machinery management, and communications alongside navigation.
In commercial practice, most major bridge-equipment suppliers (Furuno, Kongsberg, Wärtsilä SAM Electronics, JRC, Raytheon Anschütz) market systems described as IBS or INS. The key engineering commitments that distinguish a true IBS from a collection of co-located equipment items are: a shared sensor bus so that all workstations display the same validated sensor values, a single CAM alert panel per MSC.302(87), a defined failure mode where loss of one sensor or display does not cascade to another, and an ergonomic console layout certified to IEC 62288.
An IBS on a 100,000 DWT bulk carrier might comprise: two navigation workstations (port and starboard) each capable of displaying radar, ECDIS, and conning data interchangeably; a central manoeuvring console with engine telegraph, bow thruster lever, and steering stand; a communications panel with GMDSS radio, internal phone, and AIS display; and a dedicated ECDIS workstation at the chart table. The CAM display is typically mounted centrally so it is visible from all workstations without requiring the OOW to walk to a separate panel.
Bridge Resource Management and the human-element framework
SOLAS V Regulation 15 anchors bridge design in human-element principles, but the operational framework for how bridge teams use the equipment is STCW Chapter VIII, specifically Regulation 22 (Fitness for duty standards) and the STCW Code Section A-VIII, which requires ships to have a bridge resource management system that addresses assignment of tasks, situational awareness, communication, leadership, and decision-making. STCW Chapter VIII watchkeeping treats the watchkeeping standards in full.
Bridge resource management (BRM) training, required under STCW 2010 for officers in charge of a navigational watch, explicitly addresses the interface between the officer and the bridge equipment. Common failures in accident investigations include: over-reliance on a single navigation sensor (GNSS without radar cross-check), failure to monitor ECDIS safety alarms during distraction, inadequate handover at watch changes leaving the relieving officer unaware of open alerts, and failure to call the master as required by the night orders.
The overlap between INS alert management and BRM procedures is direct: MSC.302(87) ensures alerts are not silently cleared without being actioned; BRM procedures ensure the human response to a displayed alert is appropriate. A CAM system that correctly categorises and presents an approaching safety contour alarm does nothing if the OOW silences it without checking the ECDIS.
e-Navigation and the path toward MASS
IMO’s e-navigation strategy was formalised at NCSR 2 (2015) in the Strategic Implementation Plan (SIP) for e-navigation. The five e-navigation solutions adopted at NCSR 2 are: improved, harmonised bridge design (S1); means for ship-shore data sharing (S2); improved reliability, resilience, and integrity of bridge equipment (S3); integration and presentation of available information in graphical displays (S4); and improved communication of VTS services (S5).
Solution S3 directly addresses the sensor integrity question that INS integration raises. When a GNSS receiver, a gyrocompass, and a speed log all feed an INS bus, the question of which source to trust when they disagree requires a defined arbitration rule. IEC 61162-450 Annex A specifies the sensor fusion and failure detection architecture for this case, including requirements for position quality indicators and heading-sensor cross-check alarms.
MASS, Maritime Autonomous Surface Ships, represent the further development of the bridge automation concept. The IMO MASS regulatory scoping exercise (MSC 101 through MSC 106) identified four degrees of autonomy, from ship with automated processes and decision support (degree 1, which describes most modern INS installations) to fully autonomous ship (degree 4). The IMO is developing MASS-specific instruments under its MASS code work at MSC; as of 2024 a non-mandatory MASS Code has been approved for trial purposes with a mandatory version targeted for entry into force by 2028. Ships operating at degree 1 under the trial framework must still carry all SOLAS V Regulation 19 equipment, including a qualified OOW, and are not relieved of any carriage obligation by the presence of automated decision-support software.
Remote-operated vessels (degree 3) present the most complex bridge-equipment question: where the “bridge” is a shore-based remote-operations centre rather than a physical structure on the ship. SOLAS V Regulations 15 and 22 are written around a physical bridge. Adapting them to shore-based control is an active regulatory question; flag states conducting MASS trials under SOLAS V Regulation 3 have applied for, and received, specific equivalency authorisations from IMO.
Limitations
The regulatory framework described in this article reflects SOLAS V and the IMO performance standards as amended through MSC 107 (2023). Several specific limitations apply:
Flag-state equivalences. SOLAS V Regulation 3 allows flag administrations to grant equivalences for specific vessels, particularly small coastal trading ships, fishing vessels (which are not SOLAS ships), and high-speed craft under the 2000 HSC Code. A vessel operating under an equivalence may not carry equipment to the standard described here.
Domestic voyages. Many SOLAS V carriage requirements apply only to ships on international voyages. A 5,000 GT coastal bulk carrier operating entirely within national waters may hold a flag-state exemption from ECDIS carriage even though the vessel meets the gross tonnage threshold.
ENC coverage gaps. ENCs are produced by national hydrographic offices, and coverage remains incomplete for some coastal areas, particularly in parts of South and Southeast Asia, West Africa, and the Pacific islands. An ECDIS operating in an area without ENC coverage must use RNC data, which does not carry the auto-alarm functionality of an ENC cell and requires the OOW to monitor safety manually.
Sensor failure propagation in INS. When an integrated navigation system shares a single sensor bus, a corrupted sensor output can affect all workstations simultaneously if the failure mode is a plausible-but-wrong value rather than a hard failure. The MSC.252(83) requirement for sensor validation and alert on failure of input data quality is intended to catch this, but the failure modes of specific integration architectures are not universally tested.
CAM alert fatigue. MSC.302(87) centralises alert presentation but does not reduce alert quantity. An INS installation that has been commissioned without careful tuning of alert thresholds can generate dozens of caution-level alerts per watch, which officers learn to dismiss without examining. This is the opposite of the intended safety improvement. Flag-state ISM audits and PSC inspections increasingly check alert log records to verify that alerts are being actioned rather than mass-silenced.
GNSS vulnerability. All SOLAS V position-dependent functions, including ECDIS continuous position display, AIS position broadcast, VDR position recording, and INS cross-track error computation, depend on GNSS. Jamming (deliberate radio interference) and spoofing (false signal injection) of GNSS signals have been documented in several sea areas. IMO MSC-FAL.1/Circ.3 (2019) provides guidance on cyber risk management that includes GNSS vulnerability; class societies have begun requiring a GNSS anomaly detection function as a condition of INS notation.
ECDIS training compliance. STCW.7/Circ.6 (2017) required type-specific ECDIS familiarisation for each ECDIS model in use. PSC inspections have found deficiencies on vessels where officers hold generic ECDIS certificates but not the type-specific familiarisation for the installed model. The distinction between generic training (model course 1.27) and type-specific familiarisation is a persistent source of deficiencies.
See also
Related wiki articles on specific systems and their regulatory context:
- SOLAS Chapter V: Safety of Navigation: the full chapter text and section-by-section analysis
- BNWAS: Bridge Navigational Watch Alarm System: MSC.128(75) in detail, installation requirements, and testing procedures
- Voyage Data Recorder (VDR): MSC.333(90) data elements, capsule standards, annual test requirements
- AIS and ECDIS: Class A/B carriage rules, data fields, and ECDIS-AIS target fusion
- GMDSS Overview: sea area definitions, equipment schedule, DSC procedures
- SOLAS Chapter IV: Radiocommunications GMDSS: the primary GMDSS regulatory instrument
- Pilotage Operations: pilot boarding, compulsory pilotage, and bridge team roles during port approach
- Marine Engine Room Automation and Monitoring: the machinery-side equivalent of INS, including UMS notation and ECR integration with bridge telegraph
- STCW Chapter VIII: Watchkeeping: the watchkeeping standards and bridge resource management requirements
- COLREG: Steering and Sailing Rules: the rules of the road that ARPA and AIS data supports
Related calculators:
- AIS Class A Carriage: check whether a given vessel triggers the Class A carriage requirement
- Nav CPA/TCPA: manually compute closest point of approach and time to CPA for ARPA cross-check
- Nav Compass Deviation: compute corrected compass course from deviation table and variation
- Nav Sun Amplitude Compass Check: gyro error check using observed bearing of sun at rising or setting
- Nav Gyro Latitude Correction: apply gyrocompass latitude error correction
- Nav Radar Horizon: compute radar detection range given antenna height and target height
- Nav ECDIS Route Update: compute route leg parameters for ECDIS waypoint entry
- Nav Parallel Indexing: index line spacing and distance for coastal radar navigation
- Nav Dead Reckoning Error: accumulated position error during GNSS outage
- GMDSS Sea Area Coverage: check GMDSS equipment requirements for a given sea area combination