Although the sinking of DEEPWATER HORIZON was triggered by a loss of well control, the investigation revealed numerous system deficiencies and acts and omissions by Transocean and the DEEPWATER HORIZON crew that adversely impacted opportunities to limit the magnitude of the disaster. These included poor maintenance of electrical equipment that may have ignited the explosion, bypassed hydrocarbon gas alarms and automatic shutdown systems, and training shortfalls in critical areas such as engine shutdown and emergency well disconnect procedures. These and other deficiencies indicate that a flawed safety management system and safety culture aboard DEEPWATER HORIZON may have contributed to this disaster.