The “distortion of the pilot’s spatial awareness due to relative motion illusion” was the cause of a collision between the Panama-flagged car carrier City of Rotterdam, 21,143gt, and the DFDS-owned ferry Primula Seaways, 32,523gt in the Humber Estuary early in December, 2015, said the Marine Accident Investigation Branch (MAIB).
In its report into the incident, the MAIB said the collision stemmed from the City of Rotterdam being set to the northern side of the Bull Channel by the wind and the tidal stream, followed by the distortion of her pilot’s spatial awareness.
The MAIB investigation had identified that the outbound City of Rotterdam had moved into the path of the inbound ferry, but this had not been corrected because the pilot on board had become disoriented after looking through an off-axis window on the semi-circular shaped bridge.
“The pilot was under the impression that the vessel was heading to the south, whereas her heading was not altered significantly beyond the axis of the channel until a collision was imminent,” the report stated.
The report also showed that the interventions made by the port’s VTS were not “sufficiently robust” to make the pilot appreciate that more aggressive action was required to avoid the developing collision situation. “The absence of any challenge or intervention by the City of Rotterdam’s bridge team until the collision was imminent indicates an over-reliance on the pilot and a breakdown in the bridge resource management on that vessel,” the report stated.
“In addition, although the Primula Seaways’ bridge team had identified the risk of collision and had taken action to clarify the pilot’s intentions, substantial action to avoid the collision was taken too late to be effective.”
Both ships suffered damage in the collision, but they made their way to Immingham without assistance.