Outer Continental Shelf National Center of Expertise (OCSNCOE)

OCS-Related Accidents, Investigations and Safety Alerts

This page consolidates information pertaining to OCS-related accidents, investigations and safety alerts/lessons learned. Use the tabs above to view the following categories:

1) U.S. Coast Guard Investigations;

2) National Transportation Safety Board (NTSB) Marine Accident Reports and Marine Accident Briefings;

3) USCG Safety Alerts and Lessons Learned (with access to additional USCG and Bureau of Safety and Environmental Enforcement (BSEE) alerts);

4) DEEPWATER HORIZON/Macondo Well Blowout, April 20, 2010; and

5) FPS AUGER Lifeboat 6, June 30, 2019.


U.S. Coast Guard Investigation Reports for OCS-Related Casualties

The U.S. Coast Guard prepares and publishes reports of investigation that present the findings of fact, results of analysis, conclusions, and recommendations of the Coast Guard's investigation of marine casualties, outer continental shelf (OCS) casualties, and commercial diving casualties. This page lists USCG reports that are OCS-related, ordered from newest to oldest (by accident date). Additional investigation and casualty analysis reports are available on the Office of Investigations & Casualty Analysis (CG-INV) Marine Casualty Reports page.

Click on the accident date to open the document (opens in a new window).

Accident Date Vessel/Unit Type Subject and Summary
30Jun2019 Floating OCS Facility Shell AUGER TLP Lifeboat No. 6 Inadvertent Hook Opening with Loss of Life and Injury at Garden Banks 426 on the U.S. OCS in the Gulf of Mexico - Report is currently under review at USCG HQ with Commandant Actions to be determined. Release date is unknown.
View the AUGER LB 6 tab (above) for information related to this incident.
31Dec2012 MODU Multiple Related Marine Casualties and Grounding of the MODU KULLUK
MODU Explosion, Fire, Sinking and Loss of Eleven Crewmembers aboard the MODU DEEPWATER HORIZON at Mississippi Canyon Block 252 in the Gulf of Mexico
View the DWH - Macondo tab (above) for additional information.
07Apr2004 OSV Vessel Fire on the OSV SEABULK NEW JERSEY in the Gulf of Mexico
30Jun2003 OSV: Liftboat Sinking of L/B SUPERIOR CHALLENGE at Eugene Island Block 193-A in the Gulf of Mexico
04Mar1996 MODU Commercial Diving Accident aboard CLIFF'S DRILLING RIG NO. 12 with Loss of Life
15Dec1988 MODU Capsizing and Sinking of MODU ROWAN GORILLA I in the North Atlantic Ocean
15Feb1982 MODU Capsizing and Sinking of MODU OCEAN RANGER in the Atlantic Ocean with Loss of Life
10May1979 MODU Collapse and Sinking of MODU RANGER I at Block 189L offshore Galveston, TX with Loss of Life
15Apr1976 MODU Capsizing and Sinking of the OCEAN EXPRESS (Drilling Unit) in the Gulf of Mexico (under tow) with Loss of Life
28May1970 Platform Explosion and Fire on the CHAMBERS AND KENNEDY PLATFORM 189-L, southeast of Galveston, TX in the Gulf of Mexico, with damage to the M/V CARRYBACK and Loss of Life
13Mar1968 MODU Capsizing and Sinking of Drill Rig DIXILYN 8, JULIE ANN at Eugene Island Block 276 in the Gulf of Mexico
24Oct1967 Platform Explosion and Fire on CONTINENTAL Oil COMPANY PLATFORM 43-A, Grand Isle Block in the Gulf of Mexico
21Sep1960 MODU: Drill Tender Explosion and Fire onboard the M/V S-21 at Grand Isle Block 26 in the Gulf of Mexico with Loss of Life
26Jul1959 Platform Explosion and Fire onboard OFFSHORE PLATFORM SOUTH TIMBALIER BLOCK 134-D1, Gulf of Mexico, with Loss of Life
15Oct1958 Platform Fire on OFFSHORE DRILLING PLATFORM 45-E, West Delta Block in the Gulf of Mexico, with Loss of Life
17Apr1957 MODU Capsizing of DRILLING BARGE MR. K in the Gulf of Mexico with Loss of Life
10Aug1956 MODU Capsizing of SEDCO NO. 8 - RIG 22 at Avondale, LA with Loss of Life (under construction, afloat and nearing completion)


NTSB Marine Accident Reports (MARs) and Marine Accident Briefs (MABs)

National Transportation Safety Board Accident Reports "provide details about the accident, analysis of the factual data, conclusions and the probable cause of the accident, and the related safety recommendations". This page lists NTSB Marine Accident Reports that are OCS-related, ordered from newest to oldest (by accident report number). Additional accident reports and information are available on the NTSB's Accidents Reports page.

Click on the report number to open the document (opens in a new window).

Report Number Accident Date Vessel/Unit Type Subject and Summary
MAB-20/36 08Sep2019 OSV: Liftboat

Overturning of the Liftboat KRISTIN FAYE

Summary: On September 8, 2019, about 1015 local time, the liftboat Kristin Faye overturned while preparing to conduct work alongside a platform in the Gulf of Mexico, in Main Pass Block 64, located about 18 miles east of Venice, Louisiana. All three crewmembers abandoned the vessel and were rescued. One person suffered minor injuries during the evacuation. An estimated 120 gallons of diesel fuel were released. The vessel was declared a constructive total loss at an estimated $750,000.

MAB-19/36 08Oct2018 OSV: Crewboat

Fire aboard OSV GRAND SUN

Summary: On October 8, 2018, about 0215 local time, the offshore supply vessel Grand Sun was transiting the Chandeleur Sound in the Gulf of Mexico, about 15 miles from the Chandeleur Islands, Louisiana, when the vessel caught on fire. The four crewmembers aboard attempted to fight the fire but were unsuccessful. They remained on the stern of the vessel until they were rescued by the US Coast Guard. The fire burned itself out, and the vessel was later towed to port. No pollution or injuries were reported. The vessel, valued at $1.6 million, was deemed a constructive total loss.

MAB-19/27 18Nov2018 OSV: Liftboat

Overturning of the Liftboat RAM XVIII

Summary: On November 18, 2018, about 0200 local time, the liftboat Ram XVIII overturned in the Gulf of Mexico, in West Delta block 68, located about 15 miles south-southeast of Grand Isle, Louisiana. Five crewmembers and ten offshore workers abandoned the vessel and were rescued. Three personnel suffered minor injuries during the evacuation. An estimated 1,000 gallons of hydraulic oil were released. The vessel was declared a constructive total loss at an estimated $1,140,000.

MAB-15/16 24Aug2014 OSV

Collision of OSV GLORIA MAY and Fishing Vessel CAPT LE

Summary: The offshore supply vessel Gloria May collided with the uninspected fishing vessel Capt Le in the Gulf of Mexico about 2040 on the evening of August 24, 2014. As a result of the collision, the hull of the Capt Le was breached and the vessel flooded and sank; the bow of the Gloria May suffered minor damage. Three crewmembers from the Capt Le abandoned their sinking vessel into a liferaft and were recovered by the crew of the Gloria May. No injuries resulted from the accident. Total damage was estimated at $225,000.

MAB-16/06 02Mar2015 OSV: Crewboat, Liftboat

Collision between Passenger Vessel DIAMOND EDGE and Liftboat B.W. HALEY

Summary: On March 2, 2015, at 1027 local time, the passenger vessel Diamond Edge and the liftboat-configured offshore supply vessel B.W. Haley collided while under way in dense fog about 55 miles south-southwest of Lafayette, Louisiana. As a result of the collision, the hull of the Diamond Edge was breached and the vessel partially sank. There were no significant injuries or pollution reported. Estimated damage exceeded $1.75 million for both vessels combined.

MAB-16/03 23Jan2015 OSV

Allision of OSV CONNOR BORDELON with Unmanned Platform South Timbalier 271A

Summary: On January 23, 2015, at 0432 central standard time, the offshore supply vessel Connor Bordelon struck the unmanned natural gas platform South Timbalier 271A, which was located about 5.25 miles south of the jetty channel entrance at the vessel’s home port of Port Fourchon, Louisiana. The allision caused the pipelines attached to the platform to rupture and the natural gas and oil inside the pipelines to ignite. After the allision, the pipelines were shut down, and three good Samaritan vessels in the area applied water to put out the fire. The allision also caused a breach in the Connor Bordelon’s hull below the waterline, and the vessel began taking on water. The captain contacted the US Coast Guard to report the accident, and the Coast Guard released the Connor Bordelon from the accident area and allowed it to continue to Port Fourchon while the crew addressed the flooding. None of the 24 persons aboard the vessel were injured.

MAB-15/18 18Feb2014 OSV

Allision of OSV TRISTAN JANICE with Natural Gas Platform

Summary: About 0712 local time on February 18, 2014, the US-registered offshore supply vessel Tristan Janice allided with a natural gas production platform in the northern Gulf of Mexico, about 54 miles south-southwest of Houma, Louisiana. No one was injured and no water pollution resulted from the allision. However, the vessel and the platform sustained about $545,000 in total damage, and a substantial amount of natural gas escaped into the atmosphere from a ruptured supply pipe.

MAB-15/15 17Nov2014 Platform, Pipeline

Subsea Pipeline Damage by Tug and Barge VALIANT/EVERGLADES

Summary: The articulated tug and barge (ATB) unit Valiant/Everglades lost propulsion and drifted to within about 20 yards of the East Cameron (EC) 321A production platform in the Gulf of Mexico, forcing the shutdown of the platform and evacuation of its 35 crewmembers about 0600 on November 17, 2014. The captain of the Valiant ordered the anchor dropped to slow the vessel until propulsion was restored, and in the process of backing away, the anchor ruptured a subsea pipeline, causing an estimated $2 million in damage and the release of a total of about 249,800 mcf of natural gas. Neither the platform nor the vessel was damaged, and no one was injured.

MAB-15/02 28Nov2013 OSV: Dive Support

Fire on Board Saturation Diving Support Vessel OCEAN PATRIOT

Summary: A fire that broke out in the forward machinery space of the saturation diving support vessel Ocean Patriot while under way in the Gulf of Mexico on the evening of November 28, 2013, was brought under control by the vessel’s fixed fire suppression system without serious injury, and no pollution resulted from the accident. Damage to the Ocean Patriot was estimated to be $9.8 million.

MAB-15/01 14Jun2013 OSV: Crewboat

Allision and Sinking of Offshore Supply Vessel CELESTE ANN

Summary: The offshore supply vessel Celeste Ann was receiving passengers from West Delta oil platform 73 about 20 nautical miles southeast of Grand Isle, Louisiana, when the vessel allided with the platform about 0836 on June 14, 2013. The allision punctured the hull, and the Celeste Ann subsequently flooded and sank. All passengers and crew evacuated to another vessel, and no one was injured.

MAB-14/01 30May2013 OSV

Sinking of Offshore Supply Vessel RICKY B

Summary: On May 30, 2013, at 0702 central daylight time, the offshore supply vessel Ricky B sank in the Gulf of Mexico about 24 nm south of Marsh Island, Louisiana, while being towed. The three crewmembers had abandoned the Ricky B earlier and boarded a good samaritan vessel, from which they were subsequently transferred to a nearby manned oil platform. No one was injured. The Ricky B was later refloated. Its damage was estimated to be $520,000.

MAB-13/14 16Jan2012 OSV: Liftboat

Fire On Board and Sinking of Liftboat MAKO

Summary: About 0503 on January 16, 2012, the US liftboat Mako caught fire while supporting oil drilling operations about 6 miles off the coast of Nigeria, Africa. No one on board was injured, but the Mako was a total loss in the accident.

MAB-13/13 02May2012 MODU

Collision of Oil Tanker FR8 PRIDE with MODU ROWAN EXL I

Summary: On May 2, 2012, at 0718, the oil tanker FR8 Pride collided with the mobile offshore drilling unit (MODU) Rowan EXL I in Aransas Pass, Corpus Christi, Texas. No one was injured in the collision, but the two vessels sustained an estimated $16–17 million in damage.

MAR-13/01 08Sep2011 OSV: Liftboat

Liftboat TRINITY II, Personnel Abandonment and Loss of Life

Excerpt from abstract: This report discusses the September 8, 2011, accident involving the U.S. Liftboat Trinity II. Ten persons were on board. Because of severe weather and boarding seas associated with Hurricane Nate, the elevated liftboat’s stern jacking leg failed and the onboard personnel abandoned the vessel. Four of them died.

MAR-89/06 15Dec1988 MODU

ROWAN GORILLA I, Capsizing and Sinking

Excerpt from abstract: This report explains the sinking of the mobile offshore drilling unit ROWAN GORILLA I on December 15, 1988, in the North Atlantic Ocean. The safety issues discussed are the vessel's design and stability, vessel towing, weather, lifesaving equipment stowage, survival capsule design, survival training, and manning and licensing requirements.

MAR-86/03 15Jan1985 MODU

GLOMAR ARCTIC II, Explosion and Fire

Excerpt from abstract: On January 15, 1985, the U.S. semi-submersible mobile offshore drilling unit (MODU) GLOMAR ARCTIC II was conducting well testing operations 130 nautical miles east-southeast of Aberdeen, Scotland, in the North Sea. About 2030, the drilling unit experienced an explosion in the port pontoon pump room. The chief engineer and third assistant engineer were killed in the blast. Damage to the drilling vessel was estimated to be $2.3 million dollars.

MAR-85/11 14Sep1984 MODU

ZAPATA LEXINGTON, Explosion and Fire

Excerpt from abstract: About 1230 on September 14, 1984, the U.S.-flag mobile offshore drilling unit (MODU) ZAPATA LEXINGTON suffered an explosion and fire while moored and conducting drilling operations in 1,465 feet of water in the Gulf of Mexico. The accident occurred while procedures were being employed to evacuate a gas bubble from the subsea blowout preventer stack on the sea floor. Instead, gas trapped in the blowout preventer entered the base of the marine riser, rose to the surface, and escaped into the atmosphere, expelling a large volume of drilling mud out of the riser. The gas infiltrated the areas above and below the drill floor at the base of the derrick and was ignited. The explosion and fire that followed resulted in the deaths of four persons and severe injuries to three persons. Sixty-four persons abandoned the MODU using two survival capsules and three inflatable liferafts. The gas fire burned itself out about 30 minutes after the rig was evacuated. The cost of repairs was estimated at $12 million.

MAR-87/02 25Oct1983 MODU: Drillship

GLOMAR JAVA SEA, Capsizing and Sinking

Excerpt from abstract: About 2355 on October 25, 1983, the 400-foot-long United Stated drillship GLOMAR JAVA SEA capsized and sank during Typhoon LEX in the South China Sea about 65 nautical miles south-southwest of Hainan Island, People's Republic of China.  Of the 81 persons who were aboard, 35 bodies have been located, and the remaining 46 persons are missing and presumed dead.  The GLOMAR JAVA SEA currently is resting on the bottom of the sea in an inverted position in about 315 feet of water; its estimated value was $35 million.

MAR-83-2 15Feb1982 MODU

OCEAN RANGER, Capsizing and Sinking

Excerpt from abstract: About 0300 on February 15, 1982, the U.S. mobile offshore drilling unit OCEAN RANGER capsized and sank during a severe storm about 166 nautical miles east of St. John's, Newfoundland, Canada; 84 persons were aboard.  Twenty-two bodies have been recovered, and the remaining 62 persons are missing and presumed dead.  The OCEAN RANGER currently is resting in an inverted position in about 260 feet of water; its value was estimated at $125 million.

MAR-79-5 15Apr1976 MODU

OCEAN EXPRESS, Capsizing and Sinking

Excerpt from abstract: About 1100 c.s.t. on April 14, 1976, the self-elevating drilling unit OCEAN EXPRESS departed a drilling site in the Gulf of Mexico under tow for a new drilling site about 33 nm away.  The OCEAN EXPRESS arrived at the new drilling site about 2330, but was not set in place because of adverse seas.  Three tugs held the OCEAN EXPRESS in position awaiting better weather, but the seas continued to increase.  On April 15, 1976, one tug's starboard reduction gear failed, and another tug's towline broke.  With only one effective tug remaining, the OCEAN EXPRESS turned broadside to the wind and seas, drifted, grounded, capsized, and sank about 2115.  Thirteen persons drowned in a capsized survival capsule.


Safety Alerts and Lessons Learned

This page lists U.S. Coast Guard Safety Alerts and Lessons Learned that are OCS-related or pertain to systems that are onboard vessels and units that are conducting OCS activities, ordered from newest to oldest (by date). Additional safety alerts from the USCG and BSEE can be viewed at the following pages:

Office of Investigations and Casualty Analysis (CG-INV) Safety Alerts and Lessons Learned

Bureau of Safety and Environmental Enforcement Safety Alerts

Click on the safety alert number to open the document (opens in a new window).

Number Date Released Vessel/Unit Type Subject and Summary
05-20 06Jul2020 All Electrical Issues Spark Major Concern - Addressing Hazardous Area Electrical Installations Knowledge Gaps
03-20 05Feb2020 Floating OCS Facility; All Check Your Lifeboat Cables: Damaged Control Cables can Contribute to the Unintended Opening of a Hook
View the Auger LB6 tab (above) for additional/related information.
13-17 19Dec2017 All Fixed CO2 Fire Extinguishing Systems: When your hoses aren't right you might lose the fight.
10-16 16Aug2016 OSV: Crewboat; All Iron Mike will steer straight but you control your fate! Avoid Auto-Pilot Induced Casualties
02-16 04Apr2016 All Worn Thin: Vibration Abrasion, a "Short" Summation
11-15 09Nov2015 All Dried not Fried; Laundering Safety Issues
06-15 27May2015 All Fire Extinguishing Systems Ready: Are you sure?
01-15 24Feb2015 OSV; DP Vessels BSEE/USCG Joint Safety Alert: Dynamic Positioning System Failures on Offshore Supply Vessels Engaged in Oil and Gas Operations in the U.S. Outer Continental Shelf
15-14 12Nov2014 All Accidental Release of CO2 System! Importance of Design and Testing of Emergency System Controls
LL-02-14 09Jul2014 All Battery Weight Varies: Use proper replacement parts on all Emergency Equipment
LL 01-14 09Jul2014 OSV; All It's the Seemingly Minor Items... that sometimes can create a catastrophe
08-14 20May2014 OSV; DP Vessels BSEE/USCG Joint Safety Alert: Dynamic Positioning System Failures on Vessels other than Mobile Offshore Drilling Units (Vessels)
08-13 30Aug2013 All Confined Space Entry Dangers: Understanding Hazards
05-13 17Jun2013 MODU  Recent Failures of Dynamic Positioning (DP) Systems on Mobile Offshore Drilling Units
03-13b 30Apr2013 All Surge Protective Devices onboard Vessels
01-13 21Mar2013 All Counterfeit Portable Fire Extinguishers
02-11 14Feb2011 All Air Receivers and Relief Valves: A reminder that shouldn't be necessary!
01-11 31Jan2011 All Inspection of Quick-Closing Valves [Fuel Valves]
10(b)-10 21Dec2010 All Simple Failures Render CO2 System Inoperative [Fixed CO2 Fire Suppression System]
10(a)-10 21Dec2010 All Wrong Directions: A Recipe for Failure [Fixed CO2 Fire Suppression Systems]
02-03 23Mar2003 Fixed Platforms; FOFs Joint MMS/USCG Safety Alert: Deck Openings
02-98 16Jun1998 All Wire Rope Failures


DEEPWATER HORIZON - Macondo Well Blow-Out

The DEEPWATER HORIZON mobile offshore drilling unit (MODU) was performing drilling operations on the Macondo Well at Mississippi Canyon Block 252 on April 20, 2010 when a series of events led to an explosion and fire that tragically took 11 lives and injured 16 other personnel. Our condolences go out to the families and friends of the 11 men that lost their lives in this casualty.

Photo of DEEPWATER HORIZON on fire with Supply Boats responding

DEEPWATER HORIZON was severely damaged and sank on April 22. The casualty resulted in the continuous flow of hydrocarbons into the Gulf of Mexico for 87 days before the well was capped, causing the largest oil spill in U.S. history, significant environmental damage to the Gulf of Mexico and personal and economic impact to communities all along the Gulf Coast.

This page serves to consolidate information related to the incident with access to the numerous reports generated by various government agencies and involved companies. All reports are credited to the respective agency or company and are readily available through linked sites or separate internet searches.

Joint Investigation (U.S. Coast Guard & Bureau of Ocean Energy Management, Regulation and Enforcement)

The investigation into this incident was conducted by a joint investigation team consisting of members from the U.S. Coast Guard and the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE). The reports are accessible below, with excerpts from their respective executive summaries.

Excerpt from the Executive Summary: The Joint Investigation Team (JIT) comprised of members from the U.S. Coast Guard and Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) examined five aspects of this disaster relating to areas of responsibility of the U.S. Coast Guard: the explosions, the fire, the evacuation, the flooding and sinking of the MODU, and the safety systems of DEEPWATER HORIZON and its owner-operator, Transocean. Although the events leading to the sinking of DEEPWATER HORIZON were set into motion by the failure to prevent a well blowout, the investigation revealed numerous systems deficiencies, and acts and omissions by Transocean and its DEEPWATER HORIZON crew that had an adverse impact on the ability to prevent or limit the magnitude of the disaster...

JIT roadmap; Fig 1 from USCG ROI

Excerpt from the Executive Summary: This Report sets forth in detail the Panel’s investigative findings, conclusions, and recommendations. The Panel’s findings and conclusions are presented in the following subject areas: well design; cementing; possible flow paths; temporary abandonment of the Macondo well; kick detection and rig response; ignition source and explosion; the failure of the Deepwater Horizon blowout preventer; regulatory findings and conclusions; and company practices...

Chemical Safety Board Logo; Link to CSB websiteU.S. Chemical Safety Board

The U.S. Chemical Safety and Hazard Investigation Board report is available in multiple volumes that are available on their Macondo Blowout and Explosion page, as well as below for ready reference:

  • Executive Summary (opens in a new window)
  • Volume 1 (opens in a new window)
    • Macondo Incident Background and General Description
    • Deepwater Drilling and Temporary Abandonment of the Macondo Well
  • Volume 2 (opens in a new window)CSB Macondo Investigation Report, Volume 2, Figure 2-8
    • Blowout Preventer (BOP) Technical Failure Analysis
    • Barrier Management at Macondo
    • Safety Critical Elements
  • Volume 3 (opens in a new window)
    • Human Factors
    • Organizational Learning
    • Safety Performance Indicators
    • Risk Management Practices
    • Corporate Governance
    • Safety Culture
  • Volume 4 (opens in a new window)
    • U.S. Offshore Safety Regulation during and after Macondo
    • Attributes of an Effective Regulator and Regulatory System

National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling

Oil Spill Commission Logo

President Obama established the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling through Executive Order 13543 on May 21, 2010. The Commission was established to examine the relevant facts and circumstances concerning the root causes of the Deepwater Horizon oil disaster and develop options to guard against, and mitigate the impact of, oil spills associated with offshore drilling. This included recommending improvements to federal laws, regulations, and industry practices and organizational or other reforms of Federal agencies or processes necessary to ensure implementing and maintaining those improvements.

A final report on the Commission’s findings was presented to the President on January 12, 2011.

Oil Spill Commission Action Logo

The Oil Spill Commission Action project is an outgrowth of the National Oil Spill Commission, to continue efforts to make offshore oil drilling safer by promoting the implementation of the recommendations of the National Oil Spill Commission. Additional information and National Oil Spill Commission documentation is available through the OSCA website.

Commission resources are as follows (linked below for ready reference and available through the OSCA Resource Center):

  • The Commission's Final Report: DEEP WATER - The Gulf Oil Disaster and the Future of Offshore Drilling (opens in a new window)
    • Part I: The Path to Tragedy (page xiii)
      • Chapter 1: The Deepwater Horizon, the Macondo Well, and Sudden Death on the Gulf of Mexico (page 1)
      • Chapter 2: The History of Offshore Oil and Gas in the United States (page 21)
      • Chapter 3: Oversight—and Oversights—in Regulating Deepwater Energy Exploration and Production in the Gulf of Mexico (page 55)
    • Part II: Explosion and Aftermath: The Causes and Consequences of the Disaster (page 87)
      • Chapter 4: The Macondo Well and the Blowout(page 89)
      • Chapter 5: Response and Containment (page 129)
      • Chapter 6: Oiling a Rich Environment: Impacts and Assessment (page 173)
      • Chapter 7: Recovery and Restoration (page 197)
    • Part III: Lessons Learned: Industry, Government, Energy Policy (page 215)
      • Chapter 8: Changing Business as Usual (page 217)
      • Chapter 9: Investing in Safety, Investing in Response, Investing in the Gulf (page 249)
      • Chapter 10: American Energy Policy and the Future of Offshore Drilling (page 293)​
  • Commission's Recommendations (opens in a new window)
    • Recommendations (page 1)
    • Improving the Safety of Offshore Operations: Government’s Role (page 1)
    • Improving the Safety of Offshore Operations: Industry’s Role (page 12)
    • Safeguarding the Environment (page 18)
    • Strengthening Oil Spill Response, Planning, and Capacity (page 24)
    • Advancing Well-Containment Capabilities (page 31)
    • Overcoming the Impacts of the Deepwater Horizon Spill and Restoring the Gulf (page 35)
    • Ensuring Financial Responsibility (page 45)
    • Promoting Congressional Engagement to Ensure Responsible Offshore Drilling (page 50)
    • Moving to Frontier Regions (page 52)
    • Conclusion (page 57)
  • The Chief Counsel's Report: Macondo - The Gulf Oil Disaster (opens in a new window)
    • ​Executive Summary of Findings (page x)
      • Technical Findings (page x); Management Findings (page x); Regulatory Findings (page xi)
    • Chapter 1: Scope of Investigation and Methodology (page 1)
      • Nature of Report (page 1); Scope of Investigation and Report (page 1); Investigation Methodology (page 2); Structure of the Report (page 3)
    • Chapter 2: Drilling for Oil in Deepwater (page 5)
      • Oil and Gas in Deepwater (page 5); How to Drill a Deepwater Well (page 8)
    • Chapter 3: Background on the Macondo Well, the Deepwater Horizon, and the Companies Involved (page 25)
      • The Macondo Well (page 25); The Deepwater Horizon (page 26); Companies and Individuals Involved in the Macondo Blowout (page 30)
    • Chapter 4: Technical Findings (page 35)
      • Underlying Technical Causes (page 35); Underlying Management Causes (page 37)
    • Chapter 4.1: Flow Path (page 39)
      • Potential Flow Paths (page 40); Forensic Evidence Suggests That Hydrocarbons Did Not Flow up the Annulus
        and Through the Seal Assembly (page 42); Hydrocarbons Appear to Have Flowed Into and up the Production Casing (page 48); Technical Findings (page 52)
    • Chapter 4.2: Well Design (page 53)
      • Deepwater Well Design (page 53); The Macondo Well Design (page 55); Drilling the Macondo Well (page 58); Technical Findings (page 62); Management Findings (page 64)
    • Chapter 4.3: Cement (page 67)
      • Well Cementing (page 67); Preparing for the Macondo Cement Job (page 77); Designing the Macondo Cement Job (page 78); Planning for and Installing Centralizers at Macondo (page 81); Float Collar Installation and Conversion at Macondo (page 87); Pre-Cementing Wellbore Conditioning at Macondo (page 90); Cementing Process at Macondo (page 92); The Float Check at Macondo (page 93); Cement Evaluation at Macondo (page 94); Technical Findings (page 95); Management Findings (page 102)
    • Chapter 4.4: Foamed Cement Stability (page 111)
      • Foamed Cement  (page 111); Foamed Cement at Macondo (page 113); Technical Findings (page 120); Management Findings (page 123)
    • Chapter 4.5: Temporary Abandonment (page 127)
      • Temporary Abandonment (page 127); Temporary Abandonment at Macondo (page 128); Technical Findings (page 135); Management Findings (page 139)
    • Chapter 4.6: Negative Pressure Test (page 143)
      • Well Integrity Tests (page 143); Negative Pressure Test at Macondo (page 147); Technical Findings (page 160); Management Findings (page 161)
    • Chapter 4.7: Kick Detection (page 165)
      • Well Monitoring and Kick Detection (page 165); Well Monitoring at Macondo (page 174); Technical Findings (page 182); Management Findings (page 184)
    • Chapter 4.8: Kick Response (page 193)
      • Well Control Equipment (page 193); Kick Response at Macondo (page 195); Technical Findings (page 198); Management Findings (page 200)
    • Chapter 4.9: The Blowout Preventer (page 203)
      • Blind Shear Rams (page 204); Blind Shear Ram Activation at Macondo (page 206); ROV Hot Stab Activation at Macondo (page 208); Automatic Blind Shear Ram Activation at Macondo (page 208); Potential Reasons the Blind Shear Ram Failed to Seal (page 212); BOP Recertification (page 215); Technical Findings (page 216); Management Findings (page 217)
    • Chapter 4.10: Maintenance (page 221)
      • Transocean‘s Rig Management System (page 221); Competing Interests Between Drilling and Maintenance (page 222); Lack of Onshore Maintenance (page 222); Maintenance Audits and Inspections (page 223); Maintenance Findings (page 224)
    • Chapter 5: Overarching Failures of Management (page 225)
      • Leadership (page 225); Communication (page 227); Procedures (page 232); Employees (page 235); Contractors (page 237); Technology (page 240), Risk (page 242); Closing (page 249)

Figure 4.5.4 from the Chief Counsel's Report depicting Well Plan Deviations

BP Incident Investigation TeamBP Logo; Link to BP website

The BP Deepwater Horizon Accident Investigation Report (opens in a new window; contents summarized below) was published on September 8, 2010, using evidence that was available at the time and while many of the reports that were previously listed were in process.

  • Executive Summary (pdf page 9)
  • Section 1: Scope of the Investigation (pdf page 13)
  • Section 2: The Macondo Well (pdf page 15)
  • Section 3: Chronology of the Accident (pdf page 21)
  • Section 4: Overview of Deepwater Horizon Accident Analyses (pdf page 31)
  • Section 5: Deepwater Horizon Accident Analyses (pdf page 49)
    • Analysis 5A: Well Integrity Was Not Established or Failed (pdf page 51)
    • Analysis 5B: Hydrocarbons Entered the Well Undetected and Well Control Was Lost (pdf page 79)
    • Analysis 5C: Hydrocarbons Ignited on Deepwater Horizon (pdf page 109)
    • Analysis 5D: The Blowout Preventer Did Not Seal the Well (pdf page 141)
  • Section 6: Investigation Recommendations (pdf page 181)
  • Section 7: Work that the Investigation Team was Unable to Conduct (pdf page 189)
  • Appendices (pdf page 191; list only - appendices not included in the linked report)

In their report, the BP incident investigation team summarized breached barriers with the following graphic (image credit BP; Figure 1 on pages 32 and 181 of the linked BP report):

BP graphic depicting breached barriers for the Macondo Well blow-out

Transocean Investigation ReportTransocean Logo; Link to Transocean website

The Transocean Macondo Well Incident Investigation Report is available in two volumes, as linked and summarized below. Additional information is available on Transocean's website by searching "Deepwater Horizon", "Macondo", or similar terms in their site search box.

Macondo Well Incident: Transocean Investigation Report, Volume I (opens in a new window; contents summarized below)

  • Executive Summary (pdf page 9)Figure 1 from Transocean's Investigation Report, Volume I, Chapter 3.4: BOP Overview and Components
  • Chapter 1, The Macondo Prospect and the Deepwater Horizon (pdf page 13)
    • 1.1: The Macondo Well (pdf page 14)
    • 1.2: Companies Involved in Drilling the Macondo Well (pdf page 15)
    • 1.3: Deepwater Horizon History of Operations (pdf page 17)
    • 1.4: Inspections of the Deepwater Horizon (pdf page 17)
    • 1.5: Well Operations – February-April 2010 (pdf page 18)
  • Chapter 2, Incident Chronology and Overview (pdf page 21)
    • 2.1: Running Production Casing (pdf page 22)
    • 2.2: Converting the Float Collar (pdf page 22)
    • 2.3: Cementing (pdf page 23)
    • 2.4: Temporary Abandonment Plan (pdf page 24)
    • 2.5: Displacement (pdf page 25)
    • 2.6: Negative Pressure Test (pdf page 25)
    • 2.7: Sheen Test and Final Displacement (pdf page 26)
    • 2.8: Activation of the BOP (pdf page 27)
    • 2.9: Initial Emergency Response, Muster, and Evacuation (pdf page 28)
  • Chapter 3, Incident Analysis
    • 3.1: Well Design and Production Casing Cement (pdf page 35)
    • 3.2: Temporary Abandonment (pdf page 71)
    • 3.3: Drill Floor Activities (pdf page 111)
    • 3.4: Blowout Preventer (BOP) (pdf page 129)
    • 3.5: Gas Dispersion and Ignition (pdf page 167)
    • 3.6: Muster and Evacuation (pdf page 191)
  • Chapter 4, Key Findings (pdf page 203)

Macondo Well Incident: Transocean Investigation Report, Volume II (opens in a new window; Volume II contains appendices, as listed below)

  • Appendix A:  Abbreviations and Acronyms (pdf page 7)
  • Appendix B: Macondo Casing Calculations (pdf page 11)
  • Appendix C: Testing of Cementing Float (pdf page 29)
  • Appendix D: Centralization Plan at Macondo (pdf page 115)
  • Appendix E: Review of Macondo #1 7” x 9-7/8” Production Casing Cementation (pdf page 119)
  • Appendix F: Lock-Down Sleeve Decision (pdf page 121)
  • Appendix G: Hydraulic Analysis of Macondo #252 Well Prior to Incident of April 20, 2010 (pdf page 127)
  • Appendix H: BOP Modifications (pdf page 365)
  • Appendix I: BOP Maintenance History (pdf page 387)
  • Appendix J: BOP Testing (pdf page 395)
  • Appendix K: BOP Leaks (pdf page 401)
  • Appendix L: Drill Pipe in the BOP (pdf page 407)
  • Appendix M: Structural Analysis of the Macondo #252 Work String (pdf page 417)
  • Appendix N: AMF Testing (pdf page 465)
  • Appendix O: Analysis of Solenoid 103 (pdf page 475)
  • Appendix P: Deepwater Horizon Investigation: Gas Dispersion Studies (pdf page 481)
  • Appendix Q: Possible Ignition Sources (pdf page 627)

Republic of the Marshall IslandsSeal of the Republic of the Marshall Islands

The Republic of the Marshall Islands (RMI) was the Flag State Administration of the DEEPWATER HORIZON and published the RMI Investigation Report (opens in a new window) on August 17, 2011. The report contents are summarized as follows:

  • Executive Summary (pdf page 9)
    • Causal Factor Conclusions (pdf page 9); Non-Causal Factor Conclusions (pdf page 10)
  • Prologue (pdf page 13)
    • Regulatory Structure (pdf page 13); Surveys, Inspections and Certification (pdf page 17); Casualty Investigations (pdf page 19)
  • The Deepwater Horizon Marine Casualty Investigation (pdf page 21)
    • Flag State (pdf page 21); Coastal State | Joint Investigation (pdf page 22)
  • Part 1: Background of the Casualty (pdf page 25)
    • Vessel Particulars (pdf page 25); Vessel Systems (pdf page 27); Manning, Emergency Drills and Leadership (pdf page 41)
  • Part 2: Findings of Fact (pdf page 47)
    • Overview (pdf page 47); Inspections and Operations prior to 20 April 2010 (pdf page 48); Operations on 20April (pdf page 50); Well Control and Blowout (pdf page 55); Fire and Explosions (pdf page 61); Initial Emergency Response (pdf page 65); Evacuation (pdf page 67); Post Evacuation Response (pdf page 70); 21April (pdf page 70); 22 April | 23 April (pdf page 72)
  • Part 3: Conclusions (pdf page 73)
    • Causal Factors Conclusions (pdf page 73); Non-Causal Factors Conclusions (pdf page 77)
  • Part 4: Recommendations (pdf page 87)
    • Flag State/Coastal State Coordination (pdf page 87); Lifesaving Procedures (pdf page 87); Lifesaving Appliances | Power - Emergency and Standby | Safety Management | Command, Control and Organizational Structure | Vessel Alarm Systems (pdf page 88); Fire Protection - Prevention | Fire Protection Suppression Systems | Post-Evacuation Response | Response to Well Control Events (pdf page 89)
  • Annexes (pdf page 91)
    • Annex A: List of Acronyms and Abbreviations (pdf page 93)
    • Annex B: Hughes Associates, Inc. Casualty Investigation of MODU DEEPWATER HORIZON: Fire Origin Investigation, April 2011 (Fire Origin Report) (pdf page 97)
    • Annex C: GL Noble Denton and AGR FJ Brown Report of the Loss of Well Control and Assessment of Contributing Factors for the Macondo Well Mississippi Canyon Block 252 OCS-G 32306 #1 Well (Well Control Report) (pdf page 119)
    • Annex D: Overview of International Codes and Conventions (pdf page 159)
    • Annex E: MMS/USCG MOA OCS-04 dated 28 February 2008 (pdf page 165)
    • Annex F: Letter from USCG to Republic of the Marshall Islands Regarding MODU Code Equivalence (pdf page 179)
    • Annex G: List of Certificate Expiration Dates (pdf page 183)
    • Annex H: General Arrangement Diagrams (pdf page 185)
    • Annex I: Crew List (pdf page 207)
    • Annex J: Table of Testimony Regarding Change of Command (pdf page 213)


AUGER Lifeboat No. 6

This incident occurred on FPS AUGER, a Tension Leg Platform (TLP) at Garden Banks Block 426 in the Gulf of Mexico, on June 30, 2019 and resulted in the untimely deaths of two personnel and injury to a third person. The incident occurred when Lifeboat 6 released from the fall cables during recovery after a routine launch and perceived U.S. Coast Guard requirements. Our condolences go to the families of those crewmembers that lost their lives during this incident.

The USCG formal investigation has been completed and endorsed by the District Commander, Coast Guard District Eight, but is still under review for Commandant actions at USCG Headquarters. The information on this page is associated with USCG Safety Alert 03-20 that was issued as a result of findings/concerns during the investigation, until such time that the Report of Investigation for this incident is made available to the public.

Safety Alert Summary

Photo of damaged control cable with broken conduit and linerSafety Alert 03-20 was published on February 5, 2020, after observations and testing revealed that a damaged/compromised hook control cable could fail in a manner that would allow a hook to open, essentially defeating the safety features that are incorporated into the design of a lifeboat release gear system. Prior failures with these types of control cables were assumed to be 1) a seized cable or 2) a severed cable. Shell Offshore, Inc. and USCG investigation team members observed that another failure mode was possible, as summarized in the safety alert:

"During post-incident laboratory testing the Coast Guard observed that if a control cable, similar to that shown in the image above, is damaged all the way through the outer layers, leaving the traveling inner member exposed, forces applied directly on the separated outer layers can cause the traveling inner member to pull on each of its ends. As the separated outer layers pull apart, the cable’s end rod at the hook can move, which in turn can rotate the locking shaft inside the hook. If the locking shaft rotates enough, the hook can release, even without an operator touching the release handle or overriding the interlocks. The Coast Guard has no indication that a damaged control cable alone can cause a hook to release or open on-load. However, the Coast Guard believes that damaged control cables pose a significant safety risk and should be replaced before attempting to launch a boat that incorporates control cables into the on-load release capability of a hook release system."

Presentation and Videos

Safety Alert 03-20 and the observations from CG-testing were presented during the September 30, 2020 National Offshore Safety Advisory Committee (NOSAC) meeting (video teleconference). The presentation and individual videos (mp4 format) are available below. Note that the presentation is a large file size (30mb), as the videos are embedded within the presentation, but can also be downloaded separately. Microsoft PowerPoint or a compatible viewer will be needed to view the presentation.

  • Introductory Video: Separated Cable Conduit (2.5mb)
    • This video shows what happens if the conduit is extended between the fixed connections at the release unit and the hook. See the graphics below for details on the various control cable conditions and the related effects on the hook.
  • Video #1: Conduit/Liner Separation (4.2mb)
    • Testing video 1 documents U.S. Coast Guard testing and the observations upon conduit liner separation.
  • Video #2: Subsequent Cycling (after conduit/liner separation; 5.6mb)
    • Testing video 2 documents the observations of open and close cycling of the release unit after the control cable conduit (and liner) have separated.
  • Video #3: Effect of an Increasing Load (12.3mb)
    • Testing video 3 documents the effect of additional loading to a hook with the locking shaft in a partially-closed (i.e., almost-open) position due to a compromised control cable/separated conduit. As shown in the video, additional load can force the locking shaft to open and release the hook, but it has to be very close to the open position to be forced open. USCG testing showed that if the compromised control cable leaves the locking shaft in a position closer to the fully closed position, the locking shaft will not be forced open under increasing load.

Discussion of Observations and Findings

Please note that testing was conducted on Schat-Harding LHR-series release gear. As such, the descriptions of components and operation relate to that make and series of release gear. Other manufacturer's release gear designs, functions and component terminology could vary, but the ​control cable is the area of focus in these findings.

Generally, the system works in the following manner:
When closing or resetting a hook, an operator positioned at the release unit pulls up on the safety lock and pushes forward on the control handle, locking it into place. Consequently, the end rod on the hook extends. This extension causes the hook's locking shaft to rotate to the closed or locked position. When opening the hook, the opposite actions and forces apply.

A previously unknown vulnerability in the system was identified during the course of the investigation that was referenced in Safety Alert 03-20: if all three layers of the conduit of a hook cable separate or break during a reset, the locking shaft may not return to the fully-closed position. Rather, the locking shaft may come to rest at an "almost-open" position (see the various positions on the following graphics). In such a position, the hooks can support the weight of the boat and its occupants during retrieval. However, testing has revealed that an additional load can cause the locking shaft to rotate to the open position, releasing the hook.

Release Mechanism Arrangement

A typical dual-fall/hook release mechanism is comprised of two hooks, a hook release unit (located inside the lifeboat adjacent to the helm), a hydrostat unit, and three control (push-pull) cables. One control cable connects the hook release unit to the aft hook, the second control cable connects the release unit to the forward hook, and the third control cable connects the release unit to the hydrostat unit.

Graphic depicting a typical dual-fall lifeboat release gear arrangement

Closed/Reset Position

This graphic shows the positions of the control cable and the hook when the release unit handle is in the closed, or reset, position.

Open/Released Position

This graphic depicts the actions of the control cable and the hook when the release unit handle is moved into the open, or released, position.

Closed/Reset Position with compromised cover and steel layers

With the conduit cover and steel reinforcement compromised but the liner still intact, the system continues to function. In this condition, the liner is subjected to compression and tension forces that correspond to the open and close motions of the release handle that is transmitted through the control cable.

Closed/Reset Position with separated conduit (broken liner)

The conduit tends to separate after the liner breaks. This separation causes the conduit to lengthen and results in the inner member moving the locking shaft arm toward the open position. During testing, it was observed that the:

  • liner separated during the closing motion of the release handle (the liner is under tension during this motion);
  • locking shaft stopped rotating toward closed when the liner separated and remained in a partially-closed position; and
  • conduit separated during the remaining closing action of the release handle (less resistance require to separate the conduit than to rotate the locking shaft).

Effects of Increasing Load with a separated conduit

Testing confirmed that the locking shaft can be in a partially-closed position that will support the weight of the boat and occupants, but can rotate to the open position with an increasing load/additional weight (such as the additional load that can be imparted to the hooks as a boat is pulled against the davit bumpers).

Close/Reset Position with separated conduit after additional cycling

Additional cycling (opening and closing) of the release handle during testing showed that the cable conduit would separate before any rotation was transferred to the locking shaft. This condition leaves the hook in an open position that will not support any weight.

USCG Recommendations

Based on these observations, the USCG strongly recommends the following in Safety Alert 03-20:

  • Conduct thorough inspections of control cables between the release handle station and release hooks;
    • Inspect any other similar cables communicating between the release station and the hydrostatic interlock, if installed, and
    • Look for current damage and for potential hazards or other conditions that might compromise the cables in the future;
  • Photo showing an in-service (at the time it was taken) control cable with a compromised conduit (outer layers)Replace cables that show signs of wear or damage to any layers (photo to the right shows a release mechanism control cable that was in service (at the time the photo was taken) with a compromised conduit);
  • Implement an inspection regime that allows for cable damage to be identified and replace cables identified to need replacement in a timely manner.
  • Consult the lifeboat and release mechanism operations manual(s) prior to conducting launch and recovery drills.

The safety alert also noted that:

  • Photo of a Palfinger Marine Safety pins (photo to the right shows a Palfinger Marine "Training Lock" installed in a LHR-series hook) can be used during drills to prevent the hook-locking shaft from rotating, when they are approved as part of the release mechanism;
  • Although safety pins may provide an extra level of safety during drills and training, operators should ensure that lifeboats are stowed in the "ready to launch" condition without safety pins in place; and
  • Operators should ensure that lifeboat crews understand that safety pins will prevent a lifeboat from releasing from the fall wires during a real emergency if they are not removed after routine training evolutions or maintenance.