THE LATE ROBERT F DORR DETAILS HOW THE MARTIN P4M MERCATOR TURNED FROM MARITIME PATROL TO THE RISKY BUSINESS OF SIGNALS INTELLIGENCE

“It was a brute. It was big, blue, heavy iron like the Glenn L Martin Company was famous for.” So says James Horsley, a retired US Navy commander, one of the select few who piloted the big, brawny P4M Mercator on perilous Cold War reconnaissance flights – missions that were dubbed blackcover operations, named for the protective binder that held the particulars of a day’s mission. These men knew their aircraft was superior by almost every measure of performance to its competitor, the Lockheed P2V Neptune. Yet only 21 Mercators rolled out of factory doors as compared to 1,181 Neptunes.