Washington-area residents let their ears do the talking last night when they testified on a proposed three-month trial of the so-called "scatter plan" for National Airport.

Several speakers who live along the current Potomac River flight path, and thus are subjected to noisy jet takeoffs and landings, said they thought the "scatter plan" test is safe and equitable. But speakers who live in adjoining areas where overflights are not permitted now but would be under the proposed plan, said they believe the plan is neither.

Eric Cronquist, a resident of the Potomac Palisades area--which bears the brunt of the jet noise now--spoke in favor of the trial run, but said his area's citizens group still wants the number of flights at National reduced. The scatter plan test would be helpful, he said, because it would "make thousands of additional citizens aware of the dismal situation at National Airport."

About 40 people attended the three-hour hearing before the D.C. City Council's Committee on Transportation and Environmental Affairs on council member Jerry A. Moore's proposed resolution that opposes a 90-day test, which is planned for September through November.

The full City Council is to vote on the resolution Tuesday and the Metropolitan Washington Council of Governments, which must approve any test, is expected to act the next day. Alexandria and Arlington oppose the trial, while Prince George's and Montgomery counties have endorsed it.

Joseph D. Rich, representative to the Coalition on Airport problems from Advisory Neighborhood Council 3-D, an area along the Potomac in Georgetown, told the hearing that the proposal does not "transfer the burden of airplane noise from one community to another; rather, it disperses this burden."

Noting that residents under the current flight path must contend with as many as 17 flights an hour, he said "the test projects that no one area in Northwest D.C. or elsewhere will be subjected to more than one or two overflights per hour, even at peak flight hours."

But Richard Brown of the Georgetown Citizens Association said his group opposes the plan "whether it is a test plan or in operation."