The Iranian government has maintained that "Vincennes" knowingly shot down the civilian aircraft. Iran Air Flight IR655 flew every day out of Bandar Abbas—a civil as well as military airport—on a scheduled passenger flight to Dubai using established air lanes. The Italian navy and another U.S. warship, the frigate , confirmed that the plane was climbing—not diving to attack—at the time of the missile strike. The U.S. radio warnings were only broadcast on 121.5 MHz, not air traffic control frequencies and mistakenly identified the altitude and position of the plane, so the Airbus crew, if they were monitoring "guard," could have misinterpreted the warnings as referring to another aircraft. Captain David Carlson of "Sides" later said that the destruction of the airliner "marked the horrifying climax to Rogers' aggressiveness".