Attorneys representing families of those killed when a Soviet fighter shot down Korean Air Lines Flight 007 charged in court papers yesterday that someone in a U.S. air traffic control facility said "We should warn him" as the Boeing 747 jumbo jet began to stray off course.

The filing in U.S. District Court here came two days short of the second anniversary of the Sept. 1 disaster that claimed the lives of the 269 people aboard. The flight, bound from Anchorage to Seoul, was more than 340 miles off course and over Soviet waters when it was downed by Soviet fire.

Mark Dombroff, a private attorney working for the Justice Department, said that "no controller had any reason at any time to believe that anything was other than what it was supposed to be. That is true no matter what the plaintiffs may fancifully assert was on that tape."

Raymond H. Yeager, an air-traffic consultant hired by the plaintiffs, said in an affidavit that he had listened to tape recordings from the Federal Aviation Administration's Air Route Traffic Control Center in Anchorage, the last U.S. facility responsible for the flight.

"I heard a statement at 14:34:04 Greenwich Mean Time which included the words . . . 'We should warn him,' " the affidavit said.

Plaintiffs said that statement was recorded as background noise on a microphone near the controller's position, but is not part of the official communications transcript released shortly after the incident.

The transcript shows that a controller unsuccessfully tried to contact Flight 007 five times between 14:32:21 and 14:34:37 to obtain a routine position report. Flight 007 responded at 14:35:11 in a relay through a KAL flight nearby.

The Justice Department, in a motion filed Tuesday, had asked the court to forbid presentation "of disputed conversations or comments said to be present on air traffic control tapes concerning this case" until the court heard the tape "prior to entertaining plaintiffs' (or anyone else's) interpretations."

There had been no action on that when Donald W. Madole, chairman of the plaintiffs' steering committee, filed a motion containing the allegation.

When the transcript was released, FAA officials said that radio communications over the North Pacific frequently are difficult and that other aircraft often relayed position reports. Tracks of Flight 007's probable path have shown that it probably was out of radio range of the Anchorage station at the time of the transmissions.

Much of the North Pacific flight track is beyond the range of civilian radar, and air traffic controllers monitor aircraft through reported positions based on the plane's internal navigation systems rather than on radar.

U.S. Air Force radar covers part of the flight track, although the State Department has insisted since the incident that no U.S. radar facility was in position to track or warn Flight 007 after it left civilian radar coverage. Several Air Force radar stations along the Aleutian Island chain have signals "remoted" to the Anchorage Center.

The plaintiffs ask, "Why did [the controller] try repeatedly to reach Flight 7 at just that time?" They offer two possibilities:

*The controller himself was observing a nearby radar screen displaying an Air Force radar return that showed the flight's position.

*The controller had been advised by Air Force trackers that Flight 007 was straying toward Soviet air space.

Most aviation experts think Flight 007's crew erred in programming the onboard navigational computer, then flew unaware as the computer guided the plane over Soviet territory. Flight simulations by the International Civil Aviation Organization support this scenario.

Recordings of air traffic control communications are not continuous because the microphones record only when controllers or pilots are broadcasting. Background discussions on the tapes are difficult to place in context because important parts of them may be missing.

Nonetheless, the plaintiffs' assertion that there was discussion about a possible warning seems certain to encourage theorists who contend that Flight 007 was a U.S.-sponsored spy plane or one dispatched to see what the Soviet response to an intruding aircraft might be, militarily and electronically.

The most benign version is that U.S. officials were aware of the deviation but did not warn the plane, and took advantage of an intelligence "target of opportunity." U.S. officials deny all such assertions.

But the United States knows more about Flight 007 and its flight track than has been released officially, and this has been obvious from the day of the incident.

U.S. officials say, however, that their knowledge was gained after the fact, from recording radar and other intelligence sources, and was not the result of monitoring during the incident.

The plaintiff's filing was in response to a Justice Department motion to release the U.S. government as a defendant in the case. Other defendants include Korean Air Lines and the Soviet Union.