Key Questions Remain as Iran Air Probe Nears End

Although Vice President George Bush emphatically insisted Thursday that the United States was not at fault when the U.S. cruiser Vincennes shot down a commercial Iranian airliner over the Persian Gulf on July 3, the details of what happened on that fateful Sunday morning remain far from clear.

In Bahrain, a five-man Navy team headed by Rear Adm. William M. Fogarty is entering the final phase of its investigation of the downing of Iran Air Flight 655, an A-300 Airbus with 290 passengers aboard. The probe so far has failed to find evidence “that would lift the hat off your head,” said a Pentagon official.

Was Flight 655, as Defense Department officials have since said, flying at a speed virtually unheard of for airliners traveling at low altitude--but common for warplanes? Was it angling downward on a menacing path toward the Vincennes? Was it transmitting electronic signals identifying it as an Iranian F-14 fighter?

Could it be that the ultra-sophisticated electronic gear on the Vincennes supplied the ship’s crew with wrong information? Or might the crew have misinterpreted the data while they were engaged in a fire fight with Iranian gunboats?

Some of the answers may be under 180 feet of water inside the territorial waters of Iran, where much of the wreckage of Flight 655 still is out of the reach of U.S. investigators.

For now, the questions outnumber the answers. Here are some of the aspects of Flight 655 that remain shrouded in controversy:

--The plane’s speed. To the men in the Combat Information Center of the Vincennes, Iran Air Flight 655 seemed to be accelerating toward them at a speed of more than 500 m.p.h., according to Adm. William J. Crowe Jr., chairman of the Joint Chiefs of Staff. Commercial pilots say that such a speed at low altitude would cause considerable discomfort among airline passengers and is virtually unimaginable for a civilian jet.

--Its altitude. Crowe said that the unidentified plane that appeared as a single blip on the Vincennes’ digital radar screen was flying at about 9,000 feet and descending sharply when the Vincennes fired at it at a distance of about 9 miles. The U.S. frigate John H. Sides, which was positioned nearby, reported afterward that it placed the incoming aircraft at a constant altitude of 12,000 feet. Pentagon officials, however, point out that the Sides’ radar system is less sophisticated than that of the Vincennes.

--Its flight path. The day of the incident, Crowe said that the jetliner was out of the flight path from Bandar Abbas, on the southern coast of Iran, to Dubai in the United Arab Emirates. But several days later, Pentagon spokesman Dan Howard said that the plane was 4.5 to 5 miles from the center of the flight path, within normal bounds.

--Its failure to respond to seven requests by the Vincennes to identify itself. The Vincennes broadcast three warnings over the international emergency frequency that civilian Persian Gulf pilots have been urged to monitor and another four warnings over a frequency used only by military aircraft, according to the Pentagon.

--Its transponder signals. The Pentagon insists that the Vincennes picked up conflicting transponder messages from the jetliner, some identifying the plane as civilian and others as military. The Pentagon says that it knows of no case in which a civilian airliner emitted military transponder signals. However, Howard has conceded that the Sides detected the civilian transponder signals but not the military signals.

Whatever the Navy investigation ultimately determines, the Vincennes’ skipper, Capt. Will C. Rogers III, had only eight minutes from the time his ship’s electronic gear detected the approaching jetliner until his decision to shoot it down.

“The commander had a very few minutes in which to make a very crucial decision . . . and he had to make that decision based upon the information available to him at the time,” Howard said. “The investigators will take that into account as well.”