MAYDAY: Eisenhower, Khrushchev And the U-2 Affair. By Michael R. Beschloss. Harper & Row. 494 pp. $19.95.

FRANCIS GARY POWERS was supposed to be dead. The problem was he didn't know it. A few minutes earlier he had bailed out of his crippled U-2 and was now parachuting into the heart of a May Day celebration in Central Russia. At the Central Intelligence Agency and the White House, the possibility that one of the spy planes might go down over hostile territory was always a remote possibility. What Powers was never told, however, was that no U-2 pilot was ever supposed to live to reach earth. "It would be impossible," President Eisenhower remembered the CIA and Joint Chiefs assuring him, "if things should go wrong, for the Soviets to come into possession of the equipment intact -- or, unfortunately, of a live pilot." Another White House aide, Eisenhower's son John, also recalled that it was "a complete given, a complete assumption as far as we were concerned," that no pilot would be taken alive by the Soviets.

It has now been more than a quarter of a century since Frank Powers slipped a poison suicide needle into his pocket, climbed into the cockpit of U-2 Number 360, and began the odyssey which would lead to the failure of the Paris summit conference and the most severe crisis of the Eisenhower administration. Mayday, by Michael R. Beschloss, an historian at the Smithsonian Institution and author of Kennedy and Roosevelt, is a fast-paced, highly readable history of that crisis.

Although many of the details have been written about before, Beschloss skillfully weaves together an assortment of memoirs, documents from presidential libraries, declassified reports and interviews into the most comprehensive analysis of the U-2 icident to date. At the same time, through use of backnotes instead of footnotes, frequent shifts of scenes, and an abundance of detail, he has accomplished the difficult task of making a work of scholarship read like a novel.

While much has been written about the tremendous accomplishments of the U-2 program, and there were many, little has been written about the dangerous arrogance of those who ran America's early airborne reconnaissance activities. For years, even before the U-2 incident, the United States had been secretly sending military aircraft into the Soviet Union for both photographic and signals-intelligence collection. "One day, I had forty-seven airplanes flying all over Russia," boasted one Air Force general.

Yet one wonders what the U.S. reaction might have been had it suddenly discovered four dozen Russian military aircraft heading into the United States from Canada and Mexico. President Eisenhower gave an indication during the height of the U-2 program: Nothing, the president indicated to his senior military men involved in the program, would make him ask Congress to declare war "more quickly than violation of our airspace by Soviet aircraft."

ONCE, WHEN a deeper penetration was called for, a Marine general working for the CIA persuaded the British to conduct the risky mission. The Royal Air Force took a bomber, loaded it with cameras and extra fuel tanks, and flew it from West Germany down over the Soviet missile testing area of Kapustin Yar, 75 miles east of Stalingrad. By the time the aircraft reached safety in Iran its fuselage was peppered with holes.

To avoid this problem, the CIA in 1953 asked Lockheed to develop an aircraft that could fly above the reach of Soviet aircraft and surface-to-air missiles. This would allow the United States to virtually own the sky over the Soviet Union -- for a time. The result was the U-2. It could cruise at altitudes of between 68,000 and 72,000 feet, giving the aircraft n 8,000- to 12,000-foot safety buffer above the Soviet SA-1 missiles.

From the very first overflight, in the summer of 1956, the Soviets knew what was happening -- and we knew they knew what was happening. The National Security Agency constantly monitored the Soviet air defense radar systems as they helplessly tracked the invisible bird. But by 1960 the situation began changing. According to Beschloss, the Soviets began installing their new SA-2 rockets which, the CIA believed, could strike a target as high as 70,000 feet and thus eliminated the U-2's safety buffer zone. Nevertheless, the rockets were still thought to be quite inaccurate above 60,000 feet.

President Eisenhower had always harbored serious reservations about the U-2 program. He had entered office with high aspirations of improving relations with the Soviets and, he knew, a U-2 accident over Russian territory could destroy that hope. Therefore he personally scrutinized each proposed flight and route and, to the chagrin of many at CIA and Air Force, kept the numbers to the minimum.

It appears a possibility that, in order to encourage a greater number of flights, the president may not have been provided with the full details of Soviet reaction to the flights. Beschloss quotes from a memo in which an Air Force official tells the president in early 1959 that the Soviets have never fired a missile at any of the U-2s. However, former CIA deputy director Richard Bissell, who ran the spy flights, has indicated to this reviewer that missiles were in fact fired at the aircraft. In addition, Red Air Force fighters were frequently scrambled in an attempt to shoot down the intruder. On one flight from Norway to Turkey, according to Bissell, the National Security Agency recorded 56 different aircraft being scrambled against the U-2.

According to Beschloss, there appears to have been a moratorium on Soviet overflights for much of the fall of 1959 and spring of 1960. Then, strangely, although worried about the dangers of creating an incident prior to the Paris summit conference with the Soviets in the middle of May, Eisenhower approved a flight which took place on April 9. The president appeared to have mistaken Khrushchev's lack of a formal protest against the flights for acquiescence. (In fact Khrushchev was boiling mad.) As a result, shortly before the summit, he approved another flight. This, to Khrushchev, was nothing less than a deliberate insult -- planned not only to precede the summit but scheduled on the most festive day in the Soviet Union, May Day.

Beschloss is unable to provide any new answers as to how and at what height Francis Gary Powers' U-2 was shot down, but he does indicate that the weight of the evidence tends to support the pilot's story that his aircraft was disabled by the near-miss of a Soviet rocket near his cruising altitude. Nevertheless, there is also some evidence of pilot error, brought on by fatigue.

On learning of the shoot-down, President Eisenhower first put out a weak cover story and then, on learning that Powers and much of the aircraft survived the crash, admitted the spying and his knowledge of the program but, untruthfully, denied specific foreknowledge of the May Day flight. To most Americans, it came as a shock to find out that their government would lie to them. In fact, it was worse. Beschloss points out that Secretary of State Christian Herter attempted to hide the president's role in the planning of the various overflights by untruthfully telling a Senate committee investigating the incident that the approval had never "come up to the president."

Following the U-2 incident and with the advent of reconnaissance satellites shortly thereafter, the United States has apparently refrained from actual overflights. But that situation may change. Currently on the drawing boards is a new type of military space plane designed to occupy that area above the high- flying reconnaissance aircraft, about 20 miles up, and the orbits of low-flying spy satellites, about 70-miles high.

Known as a Transatmospheric Vehicle, the craft may be capable of reaching Mach 16-20 speeds and able to traverse between orbital and suborbital regions. One Air Force program considered for the TAV is the Advanced Military Spaceflight Capability, which, according to an Aerospace Daily report, is apparently "aimed specifically at flight over the Soviet Union, possibly at less than orbital altitudes." Should such a program come to pass, it may be wise to remember the history Michael Beschloss brings to us in Mayday.