Three foreign policy experts last night accused the Reagan administration and Congress of mishandling the proposed $8.5-billion sale of an Airborne Warning and Control Systems (AWACS) surveillance package to Saudi Arabia.

"I'm appalled by the misinformation and sheer ignorance that has come of the issue of the sale of the AWACS, and the ignorance is by-partisan," Herman Eilts, Boston University law professor and former U.S. ambassador to Saudi Arabia and Egypt, said last night.

Flasco

"In well over 35 years of public life, I've seldom seen a piece of legislation as mismanaged as this one," he added.

Before a group of more that 50 at a forum sponsored by the Harvard-Radcliffe Democratic Club, David S. Landes, Goelet Professor of French History, and Scott Thompson, professor at the Fletcher School of Law and Diplomacy at Tufts, joined Eilts in criticizing the handling of the controversial sale of the high-technology radar planes by American policy makers.

Prestige

"The real issue is what this implies for the possibility of peace in the Middle East," Landes said, adding, "How stupid we are to risk presidential prestige on this."

Eilts said the highly visible and vocal public debate has endangered chances for an agreement satisfactory to both Saudi Arabia and Israel.

"This kind of litmus test diplomacy, which is what AWACS has tended to become, is the worst diplomacy of all," Eilts said, adding, "When it gets into the public domain, the Saudis become much more difficult."

"I've been with Saudi officials long enough to know what is possible in an informal sense," he added.

Tolerable Risk

Eilts said, "I'd like to see the Saudis agree to joint crewing" of the planes with U.S. pilots but added that the overall risk involved in the Saudi acquisition "is likely to be one which is tolerable."

While Landes agreed with Eilts that the issue was poorly handled, he said the military package would endanger Middle East peace.

The Middle East has "been very lucky" in the past that Saudi threats of war have not materialized, Landes said, adding that peace may not survive if Saudi Arabia is equipped with AWACS.

Thompson and Eilts, however, asserted that the sale would not endanger the fragile Middle East peace and that defeat of the package--which can be vetoed by majority vote in the Senate and House--would tarnish the image of Reagan and the United States. Thompson added the rejection would force the Saudis to buy British radar planes.

"The consequences of a failure of this sale are grisly, "Thompson said, adding, "I just hope to hell [defeat of the proposal] doesn't happen because I think it's going to be a big, big problem. It would be one of the biggest fiascos of the post-war era."

However, Landes said approval of the military sale would damage U.S. credibility with Israel, which received