Crew Visas (C1/D)
An alien employed on board a non-military ship or aircraft coming to the United States must obtain a D visa. A crewperson traveling to the United States as a passenger to join a vessel or aircraft has to apply for a C1/D visa.
A "Letter of Employment" confirming the employment and requesting a crew visa is required with the application. Merchant sailors should present their seaman's book.
A dependent accompanying a crewperson entering the United States as a nonimmigrant, and not performing services required for normal operation of the ship or plane, must obtain a visitor visa (tourist), unless such dependent is entering the U.S. for another purpose (e.g. as a student) and needs a different visa.
Approved visas require one day for processing. Visa recipients can pick up their passport with visa at 16:00 the next business day after the day of their interview, unless otherwise notified.
U.S. PORT OF ENTRY
Applicants should be aware that a visa does not guarantee entry into the United States. The U.S. Department of Homeland Security (DHS) has authority to deny admission. Serbian citizens having trouble while entering the USA have the right to request contact with the Embassy of Serbia in Washington or the Consulate General of Serbia in Chicago. The Embassy can be reached by telephone at (202) 332-0333 or fax (202) 332-3933. The Consulate can be reached by telephone at (312) 670-6707 or fax (312) 670-6787. Citizens of Montenegro may wish to contact the Montenegro mission in Washington by telephone at (202) 234-6110, or (202) 234-6108, or fax (202) 234-6109.
Also, the period for which the bearer of a visitor visa is authorized to remain in the United States is determined by the DHS, not the consular officer. At the port of entry, a DHS official validates Form I-94, Record of Arrival-Departure, which notes the length of stay permitted. Those visitors who wish to stay beyond the time indicated on their Form I-94 must contact the DHS to request Form I-539, Application to Extend Status. The decision to grant or deny a request for extension of stay is made solely by the DHS.
http://belgrade.usembassy.gov/consular/nv/cv.html