Hardly a day goes by without a special U.S. Air Force electronics surveillance plane taxiing out onto the runway of the Athens International Airport here and, between the busy comings and goings of regular commercial airliners, lumbering off into the sky over the blue Aegean Sea.

The plane is one of two operating regularly from the U.S. Air Force base at Hellenikon, a facility so small and cramped by the mushrooming Athenian suburbs that its only available runway is that of the adjacent international airport.

So long have the special U.S. planes been flying out of here that their appearance on the runway amidst the commercial jetliners raises no more eyebrows than the latest charter flight from Stockholm full of pale tourists.

Neither is there any mystery that the jets' mission is one of electronic spying, listening to radio communications far beyond the frontiers of hostile territories they dare not fly over.

What is not generally known is that once the spy planes are in the air, they rarely turn north to listen in to radio conversations behind the borders of the Soviet Union and its Warsaw Pact allies as is generally believed. Instead, more often than not, they veer south toward North Africa to listen in on communications in Col. Muammar Qaddafi's Libya, the Reagan administration's public enemy number one in the Mediterranean.

The electronic eavesdropping on Libya conducted from U.S. bases in Greece is not something U.S. officials have ever liked to talk about. Since the landslide victory of Prime Minister Andreas Papandreou and his Pan-Hellenic Socialist Movement (Pasok) in national elections 10 days ago, it is a subject that actually makes U.S. officials squirm.

There is good reason for their discomfiture. Papandreou and Pasok ran for election on a platform that included as a major plank the closure of U.S. bases in Greece. Pasok's nationalistic and often neutralistic foreign policy also advocated Greece's withdrawal from the North Atlantic Treaty Organization and the European Common Market, in which Greece gained full membership in January.

Successive conservative Greek governments have defended the retention of the U.S. bases on the grounds that they are NATO-related facilities that enhance the defense of the Atlantic Alliance as well as Greece's own security from a common threat from the Warsaw Pact nations to the north.

Despite Washington's obsession with Libya, by no stretch of the imagination can it be said to fall under NATO's mandate. It also is not viewed as a threat to Greece by Papandreou who has made identification with the Third World, especially the Arab states such as Libya that ring the eastern and southern edges of the Mediterranean, an article of his foreign policy faith.

Having been sworn in a week ago as both prime minister and defense minister, Papandreou should have learned by now in briefings from his defense chiefs that at least two of the U.S. bases he has so long challenged -- the U.S. Air Force installation at Hellenikon and an Air Force-run fixed radio communications monitoring installation near Heraklion on the island of Crete -- are spending more time listening in on Libya than on NATO's communist adversaries in the north.

Such news is not believed to have been gratifying to the new Socialist prime minister. In his only comment on the U.S. bases since his election, Papandreou told a U.S. television network interviewer earlier this week that he would not act "unilaterally" to close down the bases and is ready to seek negotiations on the basis under which they could continue operations in the short term. He added, however, that he would insist on some form of Greek "control and information" on the bases to prevent "a military operation from Greek soil against any third country with which Greece has good relations."

By comparison with other U.S. bases abroad, the Greek installations that have fired so many political tempers are small. They contain about 3,500 U.S. military personnel and a like number of dependents. Most of the U.S. military presence is based in and around Athens where both the air base of Hellenikon and a U.S. Navy communications base at Nea Makri are situated. The other two bases are on opposite ends of the island of Crete: the U.S. Air Force radio monitoring installation outside Heraklion and a Navy landing strip and fleet supply depot outside the Greek Navy base of Souda Bay.

U.S. officials, who privately say there have been no changes in operations from U.S. bases here because of Papandreou's election, contend that communications monitoring operations are neither "provocation nor aggressive" since they do not involve crossing into any other nation's air space. It is unclear whether that is an argument that the prime minister will accept.

Significantly, the first foreign diplomatic envoys to be granted an audience with the prime minister after his election were representatives of four of the five members of the Arab "steadfastness and confrontation" front, Syria, Algeria, Iraq, the Palestine Liberation Organization and Libya. The Arab diplomats met with Papandreou jointly a day before he was sworn in, raising the eyebrows of Western ambassadors, many of whom have not yet met privately with the prime minister.

The irony of Papandreou's position against the U.S. bases in his native homeland is that he is the only foreign head of government in the world who both served in the U.S. Navy (during World War II) and was a U.S. citizen, during the 20-year span that he lived and taught economics in the United States before giving it all up to enter Greek politics in the early 1960s.

His disenchantment with the U.S. bases and Greece's membership in NATO, those close to the prime minister say, derives in no small part from U.S. support of the seven-year military dictatorship installed by a colonels' coup in 1967 to prevent his late father, George Papandreou, one of the grand old men of Greek politics, from forming a left-of-center government. It was compounded in 1974 by NATO inaction after the Turkish invasion of Cyprus, an independent island whose population is 80 percent Greek.

Since 1974, the U.S. bases have been blown into a symbolic issue of the Greek left that Papandreou mobilized to victory last week. The questions of Greek nationalism, historical resentments of the meddling of foreigners in their politics and wounded Hellenic pride that underlie the issue have dwarfed both the size and significance of the U.S. presence on Greek soil.

What makes continued U.S. use of these facilities problematical is that there is no official treaty governing their use.

U.S. hopes for the future of the bases have been bolstered by the fact that, at the end of the campaign, Papandreou started hedging on what he would do about the bases as well as moderating his position on withdrawal of Greece from NATO and the Common Market.