The letter from Sens. John Danforth (R-Mo.) and Robert Kasten Jr. (R-Wis.) {"Airlines Could Do Without Slots," Oct. 20} misses the point. The issue in contest is limitation of noise emanating from commercial airliners operating to and from National Airport.

The slot arrangement has enabled the Federal Aviation Administration and, more recently, the Metropolitan Washington Airports Authority to respond to widespread public demands for some measure of control over this source of aviation-related noise. The slot arrangement is identified as a noise-abatement procedure in the FAA's High Density Rule. The High Density Rule governs the MWAA administration of National and specifies 37 air carrier operations -- i.e., airlines -- plus commuter and general aviation operations for a total of 60 each hour.

The slot system has served effectively as a cap on airline operations at National and has been a key feature of efforts to curb noise caused by airliners approaching and departing National. Abandonment or weakening of the slot system would almost certainly lead to expansion of airliner traffic at National and an unacceptable increase in volume of aircraft-generated noise.

Forfeiture of a reasonably helpful means of curbing aircraft noise in the Washington area in anticipation of hypothetical increased competition and lower fares is no bargain for Washington-area residents. At least for the near future, and until the next session of Congress, good sense has prevailed on Capitol Hill, and legislation has precluded changes in the High Density Rule's slot system.

RICHARD G. BROWN Chairman, Committee on Airports and Public Utilities Citizens Association of Georgetown Washington