Aboard a UH-60A Black Hawk 100 feet over an ice-capped Potomac River, U.S. Customs Service pilot Bob Wimpy watched over one of the country’s most sensitive wedges of airspace. His jet-black, 11-ton helicopter beat a path in the frigid gray sky between the White House and Pentagon, then hovered beside the Jefferson Memorial. This week, Customs pilots began a new mission, patrolling Washington’s crowded urban skies to defend the many landmarks and vital installations in the nation’s capital from aerial threats. Full Story