Why Did the El Faro Sink?

WHOI scientists used deep-sea vehicles, including Sentry to locate the voyage data recorder (above) from the El Faro on the seafloor 15,000 feet deep. The VDR offers clues to understand why the ship tragically sank in 2015, killing 33 crew members aboard. (Photo: NTSB)

By Stephanie Murphy

Deep-sea vehicles locate data recorder on the
seafloor

On October 1, 2015, the 790-foot cargo ship El Faro sank near the
Bahamas during Hurricane Joaquin. All 33 crew members died in the
tragedy. The ship was equipped with a voyage data recorder, or
VDR, that could reveal clues to understand what happened, but it
was lost in the depths.

The VDR was mounted on the mast on the ship's navigation bridge.
A search expedition mounted in October located the wreck and
discovered that the bridge had separated from the hull. Days
later, when the search team located the bridge, the mast and the
VDR were not on it. In April 2016, the National Transportation
and Safety Board (NTSB) asked for help from Woods Hole
Oceanographic Institution, calling in two deep-sea vehicles WHOI
operates for scientific research.

Aboard the WHOI-operated research vessel Atlantis, a coordinated
team of scientists and engineers from WHOI, NTSB, and the Coast
Guard deployed Sentry, a WHOI autonomous deep-sea vehicle
equipped with a variety of sensors, sonars, and cameras to survey
the search area-creating detailed maps of the seafloor and
capturing high-resolution imagery to identify potential targets
to home in on the VDR.

The team then deployed a device called the Observation Vehicle,
which is tethered to a fiber-optic cable that allowed pilots
aboard Atlantis to control the vehicle's position over targets of
interest selected from maps generated by Sentry. The cable
transmitted real-time imagery from two high-definition color
video cameras to the search team.

At about 2 a.m. on April 26, the team found the VDR at a depth of
15,000 feet, 36 nautical miles northeast of Acklins and Crooked
Islands, Bahamas. The investigative team determined that because
of the VDR's proximity to the mast and other obstructions, it
could not accomplish recovery of the VDR with the equipment
available on the ship.

"Finding an object about the size of a basketball almost three
miles under the surface of the sea is a remarkable achievement,"
said NTSB Chairman Christopher A. Hart.

The VDR was successfully recovered from the ocean floor on August
8, 2016. It contained about 26 hours of information, including
audio from the bridge, navigational data, onboard radar images,
and wind data. In mid-December, the transcript from the audio
from the VDR was added to the NTSB's El Faro investigation docket
as part of the agency's ongoing investigation into the tragedy.
The NTSB says it considers the information captured in the VDR's
bridge audio recording critical to determining the events leading
up to the loss of the El Faro.

"We are extremely pleased to have assisted the NTSB in locating
the VDR through the use of our advanced undersea robotic tools,"
said Andy Bowen, the WHOI expedition leader onboard Atlantis. "We
hope that what is learned from the VDR and the examination of the
wreckage will help NTSB learn more about how El Faro and her crew
were lost and perhaps provide some resolution for the crew's
families and friends."

"Sentry and the Observation Vehicle were designed for
oceanographic research with funds from the National Science
Foundation, but they're also well-suited for the task of ocean
search and recovery," said Adam Soule, chief scientist for the
National Deep Submergence Facility at WHOI. "These techniques
have been honed during scientific expeditions over many years
supported by federal agencies. This is a tremendous example of
the unanticipated use of basic research that can be applied to
help benefit society."

(Source: Woods Hole Oceanographic Institution's Oceanus
Magazine)

Mar 3, 2017

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