In an effort to settle a lingering dispute about missile accuracy, senior military leaders are considering the possibility of a special test launch of a U.S. Land-based missile in a direction that more nearly approximates the path it would fly in wartime.
The problem of defining, with high confidence, the accuracy of current U.S. intercontinental-range Minutemen missiles stems from the fact that they are all test-fired east to west over water, from Vandenberg Air Force Base in California to Kwajalein Atoll in the Pacific.
But in wartime, these missiles would have to fly north, over the polar regions, from operational bases in the north-central United States to targets in the Soviet Union.
Some skeptics have warned for years that this different flight path could introduce errors into the missiles' guidance system because of differences in the polar wind and weather, the earth's gravitational pull and atmospheric disturbances.
The Soviets are believed to face similar uncertainties because their long-range missiles are tested west to east over land, from northern Russia to the Kamchatka Peninsula in the Pecific. The Soviets, however, have more of an angle on their tests, specialists say, and they also test-fire missiles occasionally from operational launch silos rather than only from special test facilities, such as the United States uses at Vandenberg.
The U.S. Air Force has never test-fired a Minuteman ICBM from an operational base.
High Pentagon civilian and military officials say the 1,000 Minuteman missiles are very accurate. The latest guidance system on the most advanced Minuteman III version reportedly is able to place an atomic warhead within 400 yards of its target after a flight of 6,000 miles.
This means that one or two Minuteman warheads aimed at an enemy underground missile silo or command post would have a high probability of distroying them.
But if north-south differences introduce errors into the course, the missiles could land off-target.
Senior officials contend that these bias effects, while introducing a degree of uncertainty, have been overstated by critics and are not serious problems in a technical sense.
These defense and military officials expressed confidence in the knowledge gained in regular east-west test firings in combination with extensive mapping of the earth's north-south gravitational fields by U.S. satellites and in simulated tests of the wartime route.
Nevertheless, the fact that initial discussions are going on with the Air Force's Strategic Air Command about an actual test indicates there is at least some concern either to put the issue to rest or to make adjustments to compensate for any significant findings.
An actual test would permit measurments of effects not only in mid-flight but also as the missile plunges earthward toward its target, something that cannot be done with satellites.
Sources stress that no decision has been made to carry out such a test and that the odds are probably against it.
However, high-ranking sources say the military now thinks it has found a way to test-launch closer to the north-south axis without being provocative toward the Soviet Union. The sources provided no details about where the missile would be fired or where it would land.