A federal judge in Manhattan has set next April 12 as the date for the first trial in the wrongful-death lawsuits stemming from the 9/11 terror attacks. The judge, Alvin K. Hellerstein of Federal District Court, who is also handling respiratory injury claims by ground zero workers, said on Tuesday he wanted to try a wrongful-death case first. “I think in many respects when we think of 9/11,” he said, “we think more of the people in the airplanes than anybody else.” Almost all of the more than 90 lawsuits filed by victims and their survivors have been settled; thousands of other claims were resolved through a special compensation fund. The judge said that he wanted the trial to be finished within a month and that it would involve either two still-pending lawsuits filed on behalf of victims who died on American Airlines Flight 11, the first plane to strike the World Trade Center; or a third unresolved suit, involving a passenger on United Airlines Flight 175, which hit the south tower of the trade center. A lawyer for the plaintiffs in the three cases, Donald A. Migliori, said he would choose by Friday which would go first.