CHERBOURG, France: French authorities began an intensive air and sea search operation Tuesday to find an American man believed to have fallen from a Channel ferry, local maritime authorities said. One passenger was missing when the overnight ferry from Portsmouth in southern Britain arrived early Tuesday at Ouistreham in northwestern France. The 65-year-old American's personal effects were found in his cabin. France has deployed a infra-red equipped fixed-wing aircraft, a helicopter and a lifeboat to search for the missing man. Authorities will decide Tuesday afternoon whether to continue the search in the chilly waters where a man in good health can survive four hours.