TSB: Box ship grounded after pilot used inexact AIS input in fogMar 5, 2015 10:50 AM
A containership ran aground in British Columbia’s Fraser River last year because the pilot, who lacked visual cues in fog, relied on electronics that he didn’t realize were inexact, investigators determined.
Canada’s Transportation Safety Board (TSB) said the 720-foot Cap Blanche grounded in a buoyed channel in the Fraser River on Jan. 25, 2014, in part because in reduced visibility the pilot relied primarily on the projected vessel positions displayed by the predictor to monitor rate of turn.
En route from Tacoma, Wash., to Fraser Surrey Docks, Cap Blanche arrived at the mouth of the Fraser River with a British Columbia coast pilot aboard at 2115 in fog. A Fraser River pilot boarded at 2118 and took over conduct of the vessel.
The pilot was positioned at the radar with a portable pilotage unit (PPU), the TSB report said. As the vessel proceeded upstream and reached buoy S8 at 2152:30, the pilot ordered the rudder 15 degrees to starboard to initiate the turn through the Steveston Bend. The pilot used the predictor to assess rate of turn. As the vessel was turning, the pilot ordered the rudder angle to be reduced to 10 degrees to starboard, 5 degrees to starboard, and then midships.
At 2153:20, when buoy S8 was about midships, the vessel’s heading was 065° gyro (G), and the rate of turn was 24.8° per minute to starboard at a speed of 14.3 knots. At 2154:30, the heading was 089° G, speed was 13 knots, and the vessel had started to turn toward the south side of the channel. The pilot ordered counter rudder to port and “full ahead” on the engine to stop the turn to starboard and correct the vessel’s position in the channel, but the vessel did not respond sufficiently. It grounded just north of buoy S10 at 2156 within the navigable channel.
The master and pilot agreed to attempt to refloat using the bow thruster. The pilot used a combination of thruster and engine movements to refloat the vessel on the rising tide. The vessel proceeded to Fraser Surrey Docks and docked at Berth 7 at 0042.
The vessel was refloated approximately 30 minutes after the grounding with only some bottom paint loss.
In its findings as to causes and contributing factors, the TSB found that the pilot didn’t realize that the predictor was inexact.
“In the absence of visual cues, the pilot relied primarily on the projected vessel positions displayed by the predictor to monitor the vessel’s rate of turn,” the report said. “The predictor function was using input from the automatic identification system (AIS) that was inexact due to the global positioning system smoothing interval, but the pilot was unaware of this.”
The TSB noted that the vessel’s rate of speed upon initiating the turn limited the time available to respond to the developing situation. The vessel’s rate of turn put the vessel on a course for the silting on the south side of the channel.
The TSB report stated that the pilot did not share information about the extent of silting in the Steveston Bend. The bridge team had not taken steps to obtain this information and was unable to assist the pilot in resolving the developing unsafe situation.
“Although the pilot applied counter rudder to arrest the turn, its effect was reduced because the vessel was decelerating,” the TSB wrote, “and the vessel ran aground just north of buoy S10.”
In its findings as to risk, TSB noted that if a navigator relies on a single piece of navigational equipment, there is a risk that potential errors or inaccuracies will go undetected. If “information that may affect the safe passage of the vessel is not communicated between bridge teams and pilots, there is a risk that unsafe situations and conditions may persist. … If pilots do not make use of the most accurate navigational equipment available to them, there is a risk they will make decisions based on imprecise information.”
The TSB also determined that the Pacific Pilotage Authority (PPA) does not have a method to track problems with equipment issued to pilots.
The TSB issued a Marine Safety Advisory letter in May 2014 to the pilotage authority providing information about the discrepancy between input from a vessel’s AIS and the pilots’ wide area augmentation system (WAAS)-based differential global positioning system (DGPS) antennas.
Later that month, the PPA distributed MSA 04/14 to all pilots and stated in the cover letter that the PPA encourages all users of portable pilotage units to also use the WAAS-based DGPS antenna and to not rely solely on vessels’ AIS inputs.
TSB documents state that the 28,372-gt Cap Blanche is owned by Blanche Schiffahrts GmbH & Co. of Germany. It was built in 2006 in Wismar, Germany.
The ship’s manager, Alnwick Harmstorf & Co. GmbH of Hamburg, did not respond to a request for comment. Blanche Schiffahrts could not be reached for comment.