A software flaw combined with the captain’s failure to use back-up controls led to the grounding of a passenger ferry last year in New York City in the United States.
The high-speed passenger ferry Commodore, owned and operated by Seastreak, was transiting northbound on the East River on 5 June 2021, when the catamaran lost primary steering and speed control to both of its port hull water jets and then grounded.
One minor injury was reported among the seven crewmembers and 107 passengers on board. The grounding resulted in USD2.5 million in damages to the vessel.
The National Transportation Safety Board (NTSB) has released its investigation report into the incident noting that after passing under the Brooklyn Bridge, an alarm alerted indicating a control failure for the port water jets. The captain unsuccessfully attempted to reconnect the port jets several times via the primary control system.
The captain first attempted to slow the vessel, then he attempted to go full astern, but only the engines and water jets in the starboard hull responded. This resulted in the ferry turning to starboard and slowing. It crossed to the east side of the river and entered the relatively narrow opening to Bushwick Inlet.
Less than two minutes after the alarm, the vessel grounded. The port hull was breached after contact with submerged pilings on the north shoreline of the Bushwick Inlet and seawater quickly entered the port engine room.
NTSB investigators found that the captain never tried to engage the back-up control, which could have been used to operate the vessel following the loss of primary control. They determined that more effective company training procedures for loss of propulsion or steering control would have included recognising a control failure and then responding by using the back-up control or other alternatives.
Following the grounding, a service engineer for the manufacturer of the primary control system determined the software system was generating an unprecedented number of error messages, which caused the SD card for the display screen controlling the port water jets and engines to fail. This failure resulted in the loss of the display monitor and the loss of primary propulsion and steering control for the water jets and main engines in the port hull.
A month after the grounding, the manufacturer issued a service letter to its customers mandating a software update that would correct the issue that caused the problem on the Commodore.
The NTSB determined the probable cause of the grounding was the loss of the primary control system for the catamaran’s port water jets and propulsion engines due to a flaw in the system manufacturer’s software causing a memory card failure.
Contributing to the casualty was the company’s lack of clear safety management system procedures for primary control system failure and ineffective oversight of crew training on failure modes for loss of propulsion and steering control, resulting in the captain not identifying the nature of the loss of control and either engaging back-up control or using emergency engine shutdowns to stop the vessel.
