Discussion: This Joint Safety Alert addresses a dynamic positioning (DP) incident on a vessel resulting in a loss of position while conducting a critical Outer Continental Shelf (OCS) activity. An equipment failure, an operational error and multiple failure modes not identified in the vessel’s Failure Modes and Effects Analysis (FMEA) combined to produce the loss of position. The OCS activity – well operations that introduced hydrocarbon flow from a well to the vessel – was critical because of the potential for loss of position to result in personal injury, environmental pollution, or catastrophic damage. These consequences were averted because of the successful actions taken by the crew, who performed an emergency disconnect from the well in accordance with established procedures.