Sort of reminds me of a Harbor Pilot[0]. A person who holds unique knowledge of how to operate a large vehicle in a particular piece of confined geography.<p>0: <a href="http:&#x2F;&#x2F;www.insidejobs.com&#x2F;careers&#x2F;harbor-pilot" rel="nofollow">http:&#x2F;&#x2F;www.insidejobs.com&#x2F;careers&#x2F;harbor-pilot</a>