Voyage Data Recorder (VDR and S-VDR) under SOLAS V/20

A voyage data recorder (VDR) is the shipborne recorder that SOLAS regulation V/20 requires “to assist in casualty investigations”: it stores the ship’s position, speed, heading, bridge and VHF audio, radar and other bridge data in a protected capsule that investigators can recover after an accident. The simplified voyage data recorder (S-VDR) is the reduced version allowed only on cargo ships of 3,000 GT and upwards built before 1 July 2002. Carriage came into SOLAS through resolution MSC.99(73), adopted on 5 December 2000 and in force on 1 July 2002, and the current performance standard is MSC.333(90) as amended by MSC.494(104).

Which standard a particular unit must meet depends on its installation date, not on the ship’s age. Four tiers run from A.861(20) of 1997 to the 2021 amendment, and the differences between them are practical ones: 12 hours of protected data or 48, one radar or both, no ECDIS record or a full chart record.

Definition and purpose

The VDR is defined in A.861(20) paragraph 4.1 as a complete system, covering the interfaces to the signal sources, the processing and encoding, the final recording medium in its capsule, the power supply and a dedicated reserve power source. Paragraph 1 of MSC.333(90) states the purpose: to keep a store of information on the position, movement, physical status, command and control of a ship over the period leading up to and following an incident, for use in any later safety investigation, and to make it available to both the Administration and the shipowner.

The recorder is evidence-gathering equipment, not a navigation aid. Nothing on the bridge depends on it, and its interfaces must not degrade the equipment it listens to (A.861(20) paragraph 7, MSC.333(90) paragraph 8). Its value appears only after something has gone wrong.

The S-VDR records less. MSC.163(78) lists 9 data items against the 15 of A.861(20) and the 20 of MSC.333(90), and it allows a single capsule of either fixed or float-free type. It was written for retrofit on existing cargo ships whose bridge equipment often had no digital output, which is why its AIS item exists: where radar data cannot be obtained, AIS target data is recorded instead (5.4.8).

The comparison with the aviation flight recorder is common and only partly right. An aircraft carries separate cockpit voice and flight data recorders; the VDR combines both functions in one system and adds radar and chart images, so a single download gives an investigator what the bridge team heard and what they saw.

Origin of the requirement

The IMO standard came first and the carriage rule followed. Resolution 12 of the 1995 SOLAS Conference asked the Maritime Safety Committee to develop performance standards for voyage data recorders “as a matter of urgency”, with particular reference to passenger ships. The Assembly adopted those standards as A.861(20) on 27 November 1997, the same session that adopted the first IMO casualty investigation code, A.849(20).

Carriage became mandatory with the revised SOLAS Chapter V. MSC.99(73), adopted on 5 December 2000, rewrote the chapter and placed the VDR in regulation 20, in force from 1 July 2002 for ships on international voyages. The existing cargo fleet was left out of that text and brought in later by the S-VDR amendment, MSC.170(79), adopted on 9 December 2004 and in force on 1 July 2006.

Existing ro-ro passenger ships were the first existing ships required to fit a VDR, at their first survey on or after 1 July 2002 under V/20.1.2, ahead of other existing passenger ships on 1 January 2004. The ro-ro passenger casualties of the period, including the MS Estonia in September 1994, are covered in their own articles.

Carriage requirement under SOLAS V/20

SOLAS regulation V/20.1 requires ships “when engaged on international voyages, subject to the provisions of regulation 1.4” to be fitted with a VDR in four cases. The regulation sits in SOLAS Chapter V , so the chapter-wide application and exemption rules in V/1 and V/3 apply to it as well as the specific exemption in V/20.3.

Passenger ships

Three paragraphs cover passenger ships , with no tonnage floor in the text:

• V/20.1.1: passenger ships constructed on or after 1 July 2002.
• V/20.1.2: ro-ro passenger ships constructed before 1 July 2002, not later than the first survey on or after 1 July 2002.
• V/20.1.3: passenger ships other than ro-ro passenger ships constructed before 1 July 2002, not later than 1 January 2004.

Ships other than passenger ships

V/20.1.4 covers ships other than passenger ships of 3,000 GT and upwards constructed on or after 1 July 2002. The tonnage is gross tonnage under the 1969 Tonnage Convention . A cargo ship of 2,999 GT built in 2015 has no SOLAS VDR obligation, although the same ship carries a bridge navigational watch alarm system , whose threshold is 150 GT.

S-VDR for cargo ships built before 1 July 2002

MSC.170(79) inserted a new paragraph 2 and renumbered the old paragraph 2 as paragraph 3. V/20.2 requires cargo ships engaged on international voyages to be fitted with a VDR “which may be a simplified voyage data recorder (S-VDR)”:

V/20.2.3 let Administrations exempt cargo ships from these dates where they would be taken permanently out of service within two years after the implementation date. The last S-VDR deadline passed on 1 July 2010, so this exemption now has historical interest only.

Exemptions and equivalents

Four routes take a ship outside V/20 or soften it:

1. V/1.4. The Administration determines to what extent regulations 15 to 28, which include regulation 20, do not apply to ships below 150 GT on any voyage, ships below 500 GT not engaged on international voyages, and fishing vessels.
2. V/3. The Administration may grant general exemptions from regulation 20 to ships without mechanical means of propulsion under V/3.1, and partial or conditional exemptions or equivalents to individual ships under V/3.2, reporting exemptions to IMO each year under V/3.3.
3. V/20.3. Administrations may exempt ships other than ro-ro passenger ships constructed before 1 July 2002 from being fitted with a VDR where interfacing a VDR with the existing equipment is “unreasonable and impracticable”. This was paragraph 2 in the 2000 text.
4. High-speed craft. SOLAS Chapter X regulation 3 deems a craft complying with the High-Speed Craft Code to comply with V/18 to V/20, so V/20 is not applied separately.

V/20 also does not reach a ship on domestic voyages. A national rule may: the regulation’s own words limit it to ships “when engaged on international voyages”.

Application dates

Performance standards by installation date

The carriage rule in V/20 says nothing about what the recorder must do; that comes from V/18.2, which requires equipment installed on or after 1 July 2002 to conform to performance standards “not inferior to those adopted by the Organization”. The IMO standards are recommendatory resolutions, given force through that reference. Operative paragraph 2 of MSC.494(104) sets out the full VDR chain:

The S-VDR chain is shorter: MSC.163(78) before 1 June 2008; MSC.163(78) as amended by MSC.214(81) from 1 June 2008; and with MSC.493(104) added for installations on or after 1 July 2022. MSC.333(90) does not apply to S-VDRs, and no later S-VDR standard has replaced MSC.163(78).

A.861(20), the 1997 standard

A.861(20) set up the basic architecture that every later standard kept: an automatic recorder, one protective capsule, a dedicated reserve power source and a fixed list of data items. The capsule had to be accessible after an incident but secure against tampering, highly visible and retro-reflective, and fitted with an appropriate device to aid location (5.1.3). There was no float-free capsule. Retention was at least 12 hours (5.3.3), and the 15 data items included one radar but no chart display and no AIS.

Section 6 of A.861(20) required means to save recorded data “by an appropriate method following an incident, with minimal interruption to the recording process”. MSC.163(78) repeats the requirement in 6.1 for the S-VDR. MSC.333(90) dropped it, so a current-standard VDR has no IMO-mandated save function.

MSC.214(81), download and playback

MSC.214(81), adopted on 12 May 2006, amended both A.861(20) and MSC.163(78) rather than replacing them. Its preamble records the problem: after an accident investigators need to download stored data and play it back “without delay”, and proprietary formats prevented that. The resolution added a new section 8 to each standard:

• a data output interface in an internationally recognized format “such as Ethernet, USB, FireWire, or equivalent” (8.1);
• a copy of the download and playback software for each installation, compatible with a commercial off-the-shelf laptop operating system, on a medium such as CD-ROM, DVD or USB stick (8.2.1, 8.2.2);
• instructions for running the software (8.2.3);
• the storage device and any special connection parts stored within the main unit (8.2.4);
• conversion of proprietary formats into open industry standard formats (8.2.5).

It applies to units fitted on or after 1 June 2008. Units fitted earlier stay on the unamended text, and the 12-hour retention is unchanged.

MSC.333(90), the 2012 revision

MSC.333(90), adopted on 22 May 2012 on the recommendation of the NAV 57 sub-committee, rewrote the standard for VDRs installed on or after 1 July 2014. Its main changes against A.861(20) are:

• Three recording media in place of one capsule: fixed, float-free and long-term (4.3 and 5.2).
• Retention of 48 hours on the fixed and float-free media and 30 days on the long-term medium (5.4.3).
• Main and emergency power both feeding the recorder (5.4.1), not the emergency source alone.
• Five new data items: ECDIS, all AIS data, rolling motion, configuration data and the electronic logbook (5.5.8, 5.5.17 to 5.5.20).
• Both radars recorded instead of one (5.5.7).
• A performance test function that can be run “at any time, e.g. annually or following repair or maintenance work” (5.1.3).
• Data integrity: no manipulation of data possible, interference attempts recorded, and an integrity check with an alarm on a non-correctable error (5.3.2, 5.3.3).

Operative paragraph 2.2 keeps installations before 1 July 2014 on A.861(20) as amended by MSC.214(81). The revision is not retroactive.

MSC.494(104) and MSC.493(104), the 2021 amendments

Both resolutions were adopted on 7 October 2021, on the recommendation of the eighth session of the NCSR Sub-Committee , as consequential amendments to MSC.471(101), the revised performance standard for float-free 406 MHz EPIRBs. MSC.494(104) replaced paragraph 5.2.2 of MSC.333(90): the float-free capsule must now comply with MSC.471(101) instead of A.810(19), and must be capable of transmitting “an initial satellite distress alerting signal and further locating and homing signals over a period of not less than seven days/168 hours”. The earlier text’s requirement for a homing signal “for at least 48 hours” does not appear in the replacement paragraph.

MSC.493(104) made the same substitution in MSC.163(78) paragraph 5.1.3.3 for S-VDR float-free capsules, deleting the references to A.810(19) and A.812(19). Both apply to installations on or after 1 July 2022.

What installed on or after means: IACS UI SC261

The installation-date tiers raise a practical question: what counts as installed when a newbuilding’s equipment is ordered years before delivery? IACS Unified Interpretation SC261, first issued in May 2013 and revised as Rev.1 in April 2022, gives the answer applied by IACS members acting as recognized organizations :

• for a ship whose building contract is placed, or which is constructed, on or after 1 July 2022, any installation;
• for any other ship, a contractual delivery date of the equipment to the ship on or after 1 July 2022, or, without one, the actual delivery date.

The interpretation applies unless the flag advises otherwise, and the classification society acting for that flag will follow the flag’s instruction.

IEC 61996-1 and IEC 61996-2

The IMO standards say what the recorder must achieve; the IEC test standards say how type approval tests it. IEC 61996-1:2013 (Edition 2.0, published 23 May 2013, with corrigendum 1 of 2014 and amendment 1 of 20 May 2021) covers the full VDR and was aligned with the MSC.333(90) three-medium architecture. IEC 61996-2:2007 (Edition 2.0, published 21 November 2007) covers the S-VDR and has no later edition. Both are issued by IEC Technical Committee 80.

The capsule survival tests for fire, impact, penetration and deep-sea pressure are set in IEC 61996-1, not in any IMO resolution. MSC.333(90) 5.2.1.3 only requires the fixed capsule to “maximize the probability of survival against fire, shock, penetration and deep-sea-pressure”. Equipment is also tested to IEC 60945 for environmental and EMC performance, which A.694(17) and MSC.333(90) 5.1.4 call up as the general requirements for shipborne radio and navigational equipment.

Data items recorded

The data list changed twice, in 2004 for the S-VDR and in 2012 for the VDR. The table compares the three texts.

For the S-VDR, MSC.163(78) 5.4.9 adds any of the A.861(20) items “when the data is available in accordance with the international digital interface standards”, using approved sentence formatters. In practice the S-VDR records the extra items only where the ship’s existing equipment already outputs them.

Navigation data

Position on most ships comes from the GNSS receiver , the usual way of meeting the requirement in SOLAS V/19.2.1.6 for a global navigation satellite system or terrestrial radionavigation receiver. Heading under A.861(20) was “as indicated by the ship’s compass”, which on a ship of 500 GT and upwards is normally the gyrocompass required by V/19.2.5.1. Speed is the item that changed: A.861(20) accepted speed through the water or over the ground, while MSC.333(90) 5.5.3 requires both, so the speed log and the position sensor both feed a current-standard recorder.

Bridge audio and VHF

MSC.333(90) 5.5.5 requires one or more microphones positioned so that conversation at or near the conning positions, radar displays, chart tables and other workstations listed in MSC/Circ.982 is recorded. Recording must stay intelligible “while there is a single audio alarm anywhere on the bridge”. The bridge is recorded on at least two channels and the bridge wings on at least one further separate channel. VHF communications relating to ship operations go on another separate channel (5.5.6), which ties the VDR to the VHF installation required under SOLAS Chapter IV .

The audio record is what lets an investigation reconstruct bridge team communication, pilot exchanges and VTS traffic. Its quality is not guaranteed by type approval alone: in the El Faro investigation the NTSB rated two audio channels poor and the bridge-wing channel unusable.

Radar, ECDIS and AIS

The radar item records the main displays of both radar installations (5.5.7), where A.861(20) recorded one, as a post-display selection of what the officer of the watch actually saw. The ECDIS item records the display in use as the primary means of navigation, plus “the source of the chart data and the version used” (5.5.8), which lets an investigator see whether the electronic navigational chart in use was up to date. All AIS data is recorded under 5.5.17. The AIS and ECDIS article covers both systems’ own carriage rules.

Alarms, doors and hull openings

Main alarms under 5.5.10 are the status of all mandatory alarms on the bridge, or alerts received from bridge alert management , “recorded as individually identified alarms”, with a footnote to table 10.1.1 of the Code on Alerts and Indicators , A.1021(26). Hull openings under 5.5.13 cover the status of openings indicated on the bridge, which on a ro-ro ship include the bow doors and stern ramps . Watertight and fire door status under 5.5.14 picks up the indicators required by SOLAS Chapter II-1 and Chapter II-2.

Rudder, engine and thrusters

Rudder order and response are recorded under 5.5.11; A.861(20) 5.4.10 already included the autopilot in this item. This is the record that shows whether the steering gear followed the helm and whether the heading and track control system was engaged. Engine and thruster orders and responses, from the engine order telegraph or direct controls, are recorded under 5.5.12.

Rolling motion, configuration data and the electronic logbook

Rolling motion comes from an electronic inclinometer where one is installed (5.5.18). Configuration data under 5.5.19 is a block written at commissioning that identifies the VDR’s sensors and settings; it must be “protected from modification other than by a duly authorized person”, and it is what tells an investigator which channel carried which signal. The electronic logbook item (5.5.20) applies only where an electronic logbook is fitted to an IMO standard.

Sensor interfaces

MSC.333(90) section 8 requires interfacing to international interface standards where possible, with a footnote to IEC 61162, the marine data interface series . The S-VDR standard is narrower still: MSC.163(78) 5.4.9 picks up an extra item only where it is available in the IEC 61162 format through approved sentence formatters. On an integrated bridge system , the VDR is one more consumer of the bridge data, and MSC.333(90) 5.1.3 names repair or maintenance of “any signal source” as an occasion for running the performance test.

Recording duration and storage media

Retention changed in 2014, and two figures apply under the current standard, so the answer to how long a VDR keeps data depends on the installation date.

12 hours under A.861(20) and MSC.163(78)

A.861(20) 5.3.3 says “The time for which all stored data items are retained should be at least 12 h.” MSC.163(78) 5.3.3 sets the same figure for the S-VDR. Data older than 12 hours is overwritten. A.861(20) section 6 also required means to save data “by an appropriate method” after an incident; on a pre-2014 recorder the crew has half a day to preserve the record before the approach to the incident starts to disappear.

Three media under MSC.333(90)

MSC.333(90) divides the final recording medium into three parts, each with its own job:

The long-term medium must be accessible from an internal, easily accessible area, readable but secured against change or deletion (5.2.3). Section 7 requires instructions in at least English, placed close to the interface. Paragraph 4.6 describes it as the medium with the longest record duration and a readily accessible interface for downloading.

Power supply and the 2-hour reserve

Under MSC.333(90) 5.4.1 the VDR operates from both the main and the emergency source of electrical power. If the ship’s supply fails, the recorder continues to record bridge audio from a dedicated reserve power source “for a period of 2 hours”, after which “all recording should cease automatically” (5.4.2). Paragraph 4.9 defines the reserve source as a battery dedicated solely to the VDR. A.861(20) 5.3.1 and 5.3.2 set the same 2-hour rule but fed the recorder from the emergency source only.

The annual test checks the figure: MSC.1/Circ.1222/Rev.1 annex 2.2 requires the unit to run for at least 1 hour 55 minutes on removal of external power and to stop recording no later than 2 hours 5 minutes.

Fixed and float-free capsules

The two protected media serve different scenarios. A fixed capsule assumes the ship sank and the wreck can be reached; a float-free capsule assumes it cannot.

The fixed protective capsule

MSC.333(90) 5.2.1 requires the fixed capsule to be accessible after an incident but secure against physical or electronic manipulation, to keep its data for at least two years after recording stops, to maximize the probability of survival against fire, shock, penetration and deep-sea pressure, to be highly visible and retro-reflective, and to carry “an appropriate device to aid location under water”. No IMO text gives that device’s frequency or operating life; those are type-approval parameters under IEC 61996-1.

The underwater locating device is a maintenance item with a dated battery. MSC.1/Circ.1222/Rev.1 annex 2.3 and 2.4 require the acoustic beacon to be shown to work and its battery to be in date at each annual test. The El Faro case below shows what happens when that check is passed on paper.

The float-free capsule

The float-free capsule must have means for grappling and recovery, keep data for at least six months after recording stops, and be secure against tampering (5.2.2). Its locating function is borrowed from the EPIRB standards:

• Installed 1 July 2014 to 30 June 2022: compliance with A.810(19), the float-free 406 MHz EPIRB standard, with an initial locating signal and a homing signal for at least 48 hours over a period of not less than 7 days (168 hours).
• Installed on or after 1 July 2022: compliance with MSC.471(101), and an initial satellite distress alert plus further locating and homing signals over not less than 7 days (168 hours), under MSC.494(104).

A capsule meeting either text is a satellite distress beacon as well as a recorder, built to the same performance standard as a float-free EPIRB . The two remain separate carriage items: the EPIRB under SOLAS IV/7.1.6, part of the GMDSS , and the capsule under V/20, so fitting one does not discharge the other. MSC.1/Circ.1222/Rev.1 annex 2.7 requires float-free arrangements and datable items to be in date, and for MSC.333(90) float-free capsules, examination in line with the EPIRB annual testing guidelines, MSC.1/Circ.1040/Rev.1.

For the S-VDR, MSC.163(78) 5.1.3.1 allows a single capsule of either type. A fixed S-VDR capsule meets the A.861(20) capsule requirements except the requirement to withstand penetration (5.1.3.2).

Recovery in practice

A float-free capsule is recovered from the surface. A fixed capsule may lie at any depth the ship reached. The El Faro capsule was located by an underwater vehicle from R/V Atlantis in April 2016 and recovered by the CURV-21 remotely operated vehicle from USNS Apache in August 2016, from 15,250 feet (about 4,650 m). The cost and practicality of a deep recovery is a decision for the flag state with the other substantially interested states, under MSC/Circ.1024 paragraph 2.3.

Annual performance test under SOLAS V/18.8

SOLAS regulation V/18.8 requires the VDR system, including all sensors, to undergo an annual performance test :

“The test shall be conducted by an approved testing or servicing facility to verify the accuracy, duration and recoverability of the recorded data. In addition, tests and inspections shall be conducted to determine the serviceability of all protective enclosures and devices fitted to aid location.”

A copy of the certificate of compliance, stating the date of compliance and the applicable performance standards, must be kept on board. The requirement applies to S-VDRs in the same way.

Who performs it

V/18.8 requires an approved testing or servicing facility. MSC.1/Circ.1222/Rev.1, approved by MSC 101 and dated 14 June 2019, says the test should be carried out by the manufacturer or a person authorized by the manufacturer. It superseded MSC.1/Circ.1222 of December 2006. The regulation states the obligation; the circular is guidance on who meets it, and the flag decides which facilities it approves.

What is examined

Annex 2 of the circular lists the examination:

1. No alarms showing before the test.
2. On removal of external power, the power supply alarm activates, the equipment runs for at least 1 hour 55 minutes and stops recording no later than 2 hours 5 minutes.
3. The acoustic beacon is functional, shown with the manufacturer’s test equipment or by substituting a certified unit.
4. The acoustic beacon and power-supply batteries are within their expiry dates.
5. Maintenance records are reviewed.
6. The data items required at original commissioning are confirmed as stored.
7. Float-free arrangements and datable items are in date, with MSC.333(90) float-free capsules examined under MSC.1/Circ.1040/Rev.1.
8. The system is restored to normal operation.

The manufacturer analyses the recording and issues the test report within 45 days (annex 3). Where the report is not in English, French or Spanish, it includes a translation (annex 4).

Timing and the survey window

MSC.1/Circ.1222/Rev.1 annex 3 allows the test up to 3 months before the due date on a passenger ship and up to 3 months either side of it on a cargo ship, with a maximum interval of 15 months for passenger ships and 18 months for cargo ships, unless the certificate is extended under SOLAS Chapter I regulation 14.

IACS UI SC279 (June 2016, applied by IACS members acting as recognized organizations from 1 July 2017) ties the test to the Harmonized System of Survey and Certification : it must be done within the time window of the annual, periodical or renewal survey, and not later than the date the survey for endorsement or renewal of the relevant certificate is completed. The same interpretation covers the AIS annual test under V/18.9 and the EPIRB annual test under IV/15.9.

There is no IMO requirement for a periodic VDR overhaul. Five-yearly shore-based maintenance is an EPIRB rule under IV/15.9, which is the source of a common confusion.

Ownership, preservation and recovery: MSC/Circ.1024

MSC/Circ.1024, “Guidelines on voyage data recorder (VDR) ownership and recovery”, was approved at MSC 75 and issued on 29 May 2002. It is often miscited as MSC.1/Circ.1024, a numbering that did not exist in 2002. Its rules are short:

• The ship owner “will, in all circumstances and at all times, own the VDR and its information”, and maintains the decoding instructions (paragraph 1).
• Recovery should happen as soon as possible after an accident, and the owner is responsible “through its on-board standing orders, for ensuring the timely preservation of this evidence” (2.1).
• On abandonment, masters should take steps to preserve the VDR information “where time and other responsibilities permit” (2.2).
• If the VDR is inaccessible, the flag state together with the substantially interested states decides whether recovery is viable and worth the cost, and the investigator co-ordinates it (2.3).
• The investigator has custody of the original information and arranges download and read-out, keeping the owner informed (3, 4).
• “A copy of the VDR information must be provided to the ship owner at an early stage in all circumstances” (5).

Saving data after an incident

No IMO instrument sets a time limit for saving VDR data. The deadline that matters is physical: on an A.861(20) or MSC.163(78) recorder the protected record is overwritten after 12 hours, and on an MSC.333(90) recorder after 48 hours on the protected media. The long-term medium holds 30 days, which gives more margin but is not designed to survive the ship.

What the save procedure looks like is a matter for the company’s ISM Code safety management system and the flag’s notices. Liberia’s Marine Operations Note 03/2023 is one example of a flag overlay: it requires the owner to preserve the data and send a complete copy, including audio, to the Administration, requires a procedure in the SMS, and directs the master to retrieve the VDR or S-VDR module before abandoning the ship where time permits. Other flags use different wording, so a fleet trading under several registers needs a procedure that meets the strictest.

On a pre-2014 recorder the save function required by A.861(20) section 6 is the first step after any incident. On an MSC.333(90) unit there is no IMO save function to press; the tool the standard provides is the download interface in section 9, which allows “download of the recorded data for a user-defined period of time” with the playback kit kept in the main unit.

VDR data in casualty investigation

The investigation framework is the Casualty Investigation Code, adopted by MSC.255(84) on 16 May 2008 and made mandatory in its Parts I and II by SOLAS regulation XI-1/6 , inserted by MSC.257(84) and in force on 1 January 2010. Part III is recommended practice that “should be taken into account to the greatest possible extent”. The Code builds on the 1997 code in A.849(20), as amended by A.884(21) of 25 November 1999.

What the Code says about the VDR

The VDR provisions sit mostly in the recommended Part III, not in the mandatory Part II:

The practical effect of 22.3.1 is that a small flag state’s investigation may rely on a larger state’s laboratory to read the recorder. Where a national investigation body such as the UK Marine Accident Investigation Branch , the Japan Transport Safety Board , the Danish Maritime Accident Investigation Board or the Dutch Safety Board has its own read-out capability, it may download the unit itself. The wider process is covered under marine casualty investigation and flag state casualty investigation reports .

Use in civil and criminal proceedings

Chapter 23 of the Code protects marine safety records from disclosure, but as a recommended practice it yields to national law. Where a court or enforcement authority obtains the data, it is the obvious evidence for a collision dispute under the COLREGs steering and sailing rules , and for checking discharge positions entered in the oil record book . The owner’s position differs from the investigator’s: MSC/Circ.1024 makes the owner the owner of the data and entitles it to a copy at an early stage.

Investigations that turned on VDR evidence

El Faro, 1 October 2015. The US-flag cargo ship sank in Hurricane Joaquin with all 33 people on board. The US National Transportation Safety Board report NTSB/MAR-17/01 records that the VDR capsule was located on 26 April 2016 but could not then be recovered, and was retrieved on 8 August 2016 from a depth of 15,250 feet. It yielded more than 26 hours of parametric data and audio from six bridge microphones; earlier audio had been recorded over, and the bridge-wing channel was unusable. The annual performance test of 2 December 2014 had noted that the acoustic locator beacon battery would expire in May 2015 and “should have been replaced”, yet “a certificate of compliance was issued without the battery being replaced”, and no beacon signal was detected in the first underwater search.

Wakashio, 25 July 2020. The grounding off Mauritius produced two investigations with different evidence, Panama’s as flag state and Japan’s. Panama’s report R-029-2021-DIAM recorded that no VDR audio was available to it, while the Japan Transport Safety Board report MA2023-10 used the VDR records. The MV Wakashio article covers both.

Port state control

A VDR is a SOLAS carriage item, so a port state control officer inspects it against V/20 and V/18.8: whether the unit is fitted and working, and whether the certificate of compliance from the last annual performance test is on board and within its interval. Regional regimes such as the Paris MoU and the Tokyo MoU record a finding under their deficiency codes .

Section 3.8 of the Paris MoU text gives a specific route for the VDR: where a compulsory VDR is not functioning and cannot be readily rectified in the port of detention, the Authority may allow the detained ship to proceed to the nearest appropriate repair yard or port, or require the defect to be rectified within 30 days.

The certificate check covers the datable items too. Circ.1222/Rev.1 requires the beacon and reserve batteries and the float-free arrangements to be in date at the test, so an inspector can compare the expiry dates on the hardware with the date on the certificate, which is the gap the El Faro test of December 2014 left open.

Interaction with other bridge systems

The VDR listens to almost every other bridge system, which makes it the record against which the others are checked:

• BNWAS. The BNWAS alarm stages appear in the VDR only if they reach it as a mandatory bridge alarm under 5.5.10. The MAIB’s 2023 safety flyer on circumvented navigational safeguards noted that the VDRs on the ships it investigated did not log BNWAS status, and the Marshall Islands requires the connection for VDRs installed on or after 1 July 2014.
• Bridge alert management. On a ship fitted with BAM to MSC.302(87), the VDR records alerts as received from the BAM system.
• ECDIS and the integrated navigation system. The ECDIS item records the display in use as the primary means of navigation (5.5.8), which on an integrated navigation system is whichever display the bridge team has set up for that purpose.
• LRIT and AIS. LRIT reports leave the ship at intervals of hours; the VDR keeps the continuous track. AIS data on an MSC.333(90) unit gives the investigator other ships’ broadcast positions as the ship received them.
• Machinery alarms. The engine room monitoring system feeds the VDR only to the extent that its alarms are mandatory bridge alarms or are configured as such.

Cyber exposure follows from the same connectivity. A VDR on the bridge network is part of the ship’s operational technology, which MSC.428(98) of 16 June 2017 encourages Administrations to see addressed in safety management systems, and maritime cyber security practice applies to its download interface and any remote-access link fitted by the manufacturer. MSC.333(90) 5.3.2 requires that data cannot be manipulated and that attempts at interference are recorded.

Misreadings to avoid

None of the following statements is supported by the instruments:

• “IACS UR M51 governs VDR survey.” UR M51 is the IACS requirement for factory acceptance testing of internal combustion engines. The IACS VDR documents are UI SC261 and UI SC279.
• “The VDR must be overhauled every five years.” No IMO text says so. The five-year item is EPIRB shore-based maintenance under SOLAS IV/15.9.
• “The capsule has a six-month battery.” Six months in MSC.333(90) 5.2.2.2 is how long the float-free capsule keeps its data after recording stops, not a battery life.
• “MSC.333(90) requires an incident-save button.” It does not; the save requirement is in A.861(20) section 6 and MSC.163(78) 6.1.
• “Data must be saved within 24 hours.” No IMO instrument sets a time limit.
• “IEC 61996-2:2018.” The current S-VDR test standard is IEC 61996-2:2007.
• “MSC.214(81) replaced A.861(20).” It amended A.861(20) and MSC.163(78) by adding the download and playback section.

Limitations

This article states the IMO baseline from the resolution texts and the IACS interpretations cited above. It does not reproduce the IEC 61996-1 type-approval test levels for fire, impact, penetration, pressure or the underwater locating device, and figures quoted for those parameters elsewhere should be checked against the edition of IEC 61996-1 to which the particular unit was approved. Manufacturer service intervals, battery lives and prices vary by model and are not covered.

Flag-state rules on data preservation, retention and copies to the Administration differ, and the Liberian example is one register’s text, not a general rule. The European Union applies its own marine equipment approval regime, under the EU Marine Equipment Directive , on top of the IMO standards, and national law decides how far VDR data can be used in court, whatever chapter 23 of the Casualty Investigation Code recommends. MSC.1/Circ.1222/Rev.1 still frames its data-storage check around the 12-hour recording period of A.861(20), and does not set a separate test duration for MSC.333(90) units. Where the flag, the class society and the manufacturer’s instructions disagree, the flag’s instruction prevails for statutory purposes.

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