NATO officials have launched a massive search-and-rescue mission to locate the pilot of an American F-16 fighter shot down this morning over northern Bosnia near the Bosnian Serb town of Banja Luka. The plane was flying at approximately 20,000 feet on an air patrol mission enforcing the no-fly zone over Bosnian Serb territory when it was hit by a Russian SA-6 surface-to-air missile. Only the pilot was aboard. It is not yet known whether he survived the crash. The Pentagon has not yet released his identity. This is the second time a NATO plane has been shot down by Serb missiles. The first came in April of 1994, when a British fighter plane was hit.