Navy pilots who shot down two Libyan MiG23 fighters last week used tactics that exploited weaknesses of the Soviet-made aircraft learned in mock combat between U.S. planes and clandestinely obtained Soviet warplanes at secrecy-shrouded Air Force bases in the Southwest. The single-seat MiG23 proved suprisingly fast and surprisingly "blind" when U.S. pilots put the fighter through its paces years ago at one of the secret bases where American military fliers learn what Soviet aircraft can and cannot do, Pentagon sources said. Both superpowers have clandestinely obtained each other's arms for years, so their vulnerabilities and strengths can be found and exploited or avoided. The MiG23, U.S. pilots have learned, has a small, weak radar, giving its pilot difficulty in detecting and directing long-range missiles to low-flying targets out of sight, according to military experts. The Navy F14 crews during the encounter over the Mediterranean last week remembered this and positioned themselves at low altitude to exploit the MiG23's lookdown blind spot, according to Pentagon accounts. By going low early in the engagement, they also sought to silently signal the oncoming Libyan pilots that a dogfight would end badly for them and they should go home. In previous aerial encounters, the Libyans have turned back when they detected the powerful radars of F14s sweeping their MiGs. U.S. experts may have obtained clues from classified radio intercepts that could explain why they did not retreat last week. The Libyan MiG23s, codenamed Flogger by NATO, were being directed toward the F14s by controllers at their airbase's radar station at Al Bumbah. U.S. Navy communications-gathering aircraft, the EA6B and E2C, were aloft nearby, and the National Security Agency has an elaborate eavesdropping net spread over the area. Pentagon spokesman Dan Howard said the United States had obtained "some intercept" of radio talk between Libyan pilots and controllers. He said the ground controllers told the MiGs where the F14s were. But what the United States intercepted, whether the intercepts revealed the MiG23s' intentions, or how much guidance the MiGs received are among the air battle's many unknowns. Chairman Les Aspin (D-Wis.) of the House Armed Services Committee said his panel will conduct an inquiry into the incident. The intercepts, if the committee receives them, may explain what the Libyans had in mind during this latest encounter in the twilight zone between war and peace. But what is clear now is that the two-man crews of the F14s from the aircraft carrier USS John F. Kennedy used tactics honed from the mock battles with MiG23 Floggers over the Southwest desert. The heavily censored videotape of the Navy crews' cockpit chatter released by the Pentagon indicates the F14s stayed in the blindspot under the MiG23s when the first shots were fired: As the radar intercept officer in the rear seat of one F14 armed the plane's Sparrow and Sidewinder missiles and set up for a shot, another aviator demanded to know the altitude of the MiG Floggers. "Say your angels," the aviator demanded. "I'm at angels 5," replied the radar intercept officer, meaning his F14 was at 5,000 feet, low for flying over water. "His angels," snapped an impatient voice. "Angels are at nine," answered the radar intercept officer, meaning the MiG23s were at 9,000 feet, 4,000 feet above the Navy jet. Compounding the MiGs' lookdown problem, aviators said, was the "clutter" of atmospheric interference that hung over the Mediterranean Jan. 4, and further clouded the radar scopes of the MiG23s when two Sparrow missiles came up from the lead F14 below. The first missile was fired from 12 miles and the second at 10 miles. For unknown reasons, both missed. The Floggers apparently turned toward the second F14, which shot down one of the Soviet-built planes with a Sparrow. Twenty seconds later, the command F14 downed the remaining MiG with a Sidewinder heat-seeking missile. Aviators who have engaged in numerous intercepts listed these as possible explanations for why the Libyans broke with past practice and continued toward the F14s after they had been painted with aircraft radar: The MiGs were sent out to see if the U.S. aircraft spotted off the Libyan coast by Libyan radar were bombers bound for the Libyan chemical plant President Reagan had hinted that he might attack; Libyan leader Moammar Gadhafi intended to taunt the United States by sending his fast MiGs past the Kennedy in a thumb-nosing "hi-bye;" the Libyan pilots were not called back to shore by their controllers when they got close to the F14s, either deliberately or because of a radio breakdown, and found themselves in a dogfight with no authority to fire any shots. The Pentagon has said the MiGs were equipped with Soviet-made Apex and Aphid missiles for aerial combat but did not list any air-to-surface missiles on board which could have been shot at the Kennedy. The MiG23 has been operational for about two decades. They equip numerous Third World countries' air forces, as front-line fighters. The 52-foot-long plane can speed at 900 mph at low altitude, far faster than U.S. experts anticipated before they began the mock battles with a "U.S." Flogger. "I have to assume," said a Pentagon official who has viewed a sample MiG23 at one of the bases, "they {the Soviets} know that we have it and flown it." The flight testing has been too extensive to hide, according to defense officials familiar with this part of the "black" world where Soviet weapons are obtained through a tangled and secret process so their vulnerabilities can be discovered and taught. The Soviet Union does the same thing with American weapons. U.S. aircraft and other weapons downed, captured or left behind during the Vietnam war provided the Soviets with a technology trove to copy and combat by changing tactics and hardware, according to military officials. Libya to Hand Over Body Of American Aviator Associated Press ROME, Jan. 12 -- The Libyan government said it will hand over on Friday the body of a U.S. aviator killed in the 1986 air raid on Tripoli, the North African country's official news agency reported. The body, believed to be that of Capt. Paul Lorence, was to be given to a Vatican representative, who will turn it over to the U.S. Embassy in Rome, Vatican officials said. In Washington, a State Department official said U.S. officials will make every effort to confirm the identity of the remains if they are turned over. Type: Single-seat air combat fighter Crew: Pilot only Maximum level speed: Mach 2.35 Wingspan, unswept: 45 feet, 9 inches Length overall: About 52 feet (excluding nose probe)