for development of SAR technology,
and the Coast Guard is a promising research partner. As of the time of writing, its funding is modest, so synergies
and advocacy from well-funded com-puter-science projects would likely be
welcome.
In hindsight, the clearest lessons
for the volunteer search team were that
the ocean is enormous, and the Coast
Guard has a sophisticated and effective maritime SAR program. The meeting in Berkeley opened with a briefing
from Arthur Allen, an oceanographer
at the Coast Guard Headquarters Office of Search and Rescue, which oversees all Coast Guard searches, with an
area of responsibility covering most
of the Pacific, half of the Atlantic, and
half of the Arctic Oceans. Here, we review some of the main points Allen
raised at the meeting.
SAR technology is needed only
when people get into trouble. From a
public-policy perspective, it is cheaper
and more effective to invest in preventing people from getting into trouble
than in ways of saving them later; further discussion of boating safety can
be found at http://www.uscgboating.
org. We cannot overemphasize the importance of safety and prevention in
saving lives; the longer version of this
article3 includes more on voluntary
tracking technologies and possible extensions.
Even with excellent public safety,
SAR efforts are needed to handle the
steady stream of low-probability events
triggered by people getting into trouble. When notification of trouble is
quick, the planning and search phases
become trivial, and the SAR activity
can jump straight to rescue recovery.
SAR is more difficult when notification
is delayed, as it was with Gray. This
leads to an iterative process of planning and search. Initial planning is
intended to be quick, often consisting
simply of the decision to deploy planes
for a visual sweep of the area where a
boat is expected to be. When an initial
“alpha” search is not successful, the
planning phase becomes more deliberate. The second, or “bravo,” search
is planned via software using statistical methods to model probabilities
of a boat’s location. The Coast Guard
developed a software package for this
process called SAROPS, 5 which treats
Gray was famous
for many things,
including his
determination
to work with
practitioners
to transform
the practical
challenges they
faced into scientific
questions that
could be formalized
and addressed
by the research
community.
the boat-location task as a probabi-listic planning problem it addresses
with Bayesian machine-learning techniques. The software accounts for
prior information about weather and
ocean conditions and the properties
of the missing vessel, as well as the
negative information from the alpha
search. It uses a Monte Carlo particle-filtering approach to infer a distribution of boat locations, making suggestions for optimal search patterns.
SAROPS is an ongoing effort updated
with models of various vessels in different states, including broken mast,
rudder missing, and keel missing. The
statistical training experiments to parameterize these models are expensive
exercises that place vessels underway
to track their movement. The Coast
Guard continues to conduct these experiments on various parameters as
funds and time permit. No equivalent
software package or methodology is
currently available for land-based SAR.
Allen shared the Coast Guard’s
SAR statistics, 2003–2006, which are
included in the longer version of this
article. 3 They show that most cases occur close to shore, with many involving land-based vehicles going into the
ocean. The opportunities for technologists to assist with maritime SAR are
modest. In Allen’s U.S. statistics, fewer
than 1,000 lives were confirmed lost in
boating accidents each year, and only
200 to 300 deaths occur after the Coast
Guard had been notified and thus
might have been avoided through rescue. A further 600 people per year remain unaccounted for, and, while it is
unknown how many of them remained
alive post-notification, some fraction
of them are believe to have committed
suicide. Relative to other opportunities to save lives through technology,
the margin for improvement in maritime SAR is relatively small. This reality frames the rest of our discussion,
focusing on learning lessons from our
experience that apply to SAR and hopefully other important settings as well.
Communication and Coordination
As in many situations involving groups
of people sharing a common goal,
communication and coordination
were major aspects of the volunteer
search for Gray. Organizing these
“back-office” tasks were ad hoc and