The first of what will be a flood of lawsuits has been filed against both KLM Royal Dutch Airlines and Pan Am after the collision last Sunday of their jumbo jets on a runway in the Canary Islands killed 577 people.

Meanwhile, U.S. investigators are examining the possibility that a partially blocked radio transmission from the Pan Am plane itself may have led the KLM pilot to believe that the Pan Am plane was clear of the runway and that takeoff could safely begin, The Washington Post has learned.

Instead, the Pan Am jet, carrying 396 people, was still on the fog-shrouded runway. It swerved to the left as the KLM jet bore down on it, but it was too late to avert the collision. There were no survivors on the KLM jet, which carried 248 people. There are 67 survivors.

One of those survivors was John Amador, 35, of Los Angeles. He filed suit in a New York state court Friday against the two airlines, charging that he had suffered "severe and painful permanent injuries of a bodily and psychic nature," according to the complaint.

Amador is seeking $75,000 from Pan Am and $250,000 from KLM. Insurance experts have estimated that claims could total $100 million to $200 million.

Settlements from the world's worst previous air crash - the Turkish Airlines DC-10 that went down outside Paris in 1974 and killed all 346 aboard - have topped $80 million and are expected to surpass $100 million before all litigation is completed.

Amador is represented by Speiser, Krause and Madole, a law firm that specializes in aviation litigation. Donald Madole, a Washington partner and one of the leading attorneys in the Paris air-crash litigation, said yesterday that "We will be filing suits in the death cases after identifications are established."

The bodies of 326 people on the Pan Am plane are scheduled to be flown today from Los Rodeos Airport in Santa Cruz de Tenerife, where the crash occurred. The first of two jet freighters is scheduled to arrive in Dover, Del., Air Force Base, at 11 a.m. with the second to follow two hours later.

A special team of experts from the FBI and the Armed Forces Institute of Pathology has been assembled in Dover to expedite identification. Most of the bodies are badly burned.

The bodies from the Dutch plane were removed from Tenerife yesterday and taken to Amsterdam.

Spanish, U.S. and Dutch experts will begin Monday listening to the recordings made in the cockpits of each airplane. Those recordings, under the control of Spanish authorities, have been brought to Washington to take advantage of special equipment at the National Transportation Safety Board offices.

Investigators have already heard a recording of the radio transmissions as sent and received from the Spanish-operated control tower.

In the moments before the accident, according to sources who have heard the tape, the Spanish controller instructed the KLM pilot, in English, as follows:

"Hold in position (at the end of the runway) until Clipper is clear . . ." Clipper was the radio name for the Pan Am flight, a charter.

Shortly thereafter, the Pan Am crew radioed, "Will advise when Clipper is clear." According to the sources, however, there are indications that there was radio interference when the words "will advise when" were being transmitted.

Thus, they theorize, it is possible that the KLM pilot could have heard the Pan Am pilot say only, "Clipper is clear," indicating a wide-open runway. The tower and both airplances were using the same radio frequency, so each theoretically heard what the others were saying.

Dutch civil aviation investigators have admitted that the KLM craft took off without an appropriate clearance from air traffic control. Such a clearance would normally consist of the words, "cleared for takeoff." Since that disclosure Tuesday, the investigation has concentrated on why the Dutch captain presumably assumed he had a valid clearance.

Everyone who has heard the tower tape acrees that there was no language barrier - everyone spoke adequate, understandable English - despite the different nationalities involved.

Pan Am spokesman Paul Friend said yesterday that Amador's suit was the first "we have heard about."

Amador's father, Charles, told reporters in Los Angeles Monday that Amador had lost a close friend, Harry Harper, in the crash. Amador escaped by jumping through a ring of flames, but was prevented by the captain from returning to save Harper, the father said.

Pam Am's Friend said he met Amador in New York when the survivors returned from the Canary Islands. "He didn't have a Band-Aid." Friend said. "But he was a little uptight. He kept referring to his friend and saying, 'Harry didn't make it.'"