Fewer Washington area citizens would hear a lot of noise but many more than do so today would hear some noise under a share-the-airlane proposed the Federal Avision Administration in suggesting for friends and neighbors of national Airport's flight paths.
The proposal was made by the FAA last month. Yesterday, a consultant came forth with a detailed technical explanation of what it all means. The Metropolitan Washington Council of Governments is setting up a series of meetings in may so area citizens can give their views and ask questions.
The bottom line, according to the Mitre Corporation's consultant's study, is that the alternative flight paths proposed by the FAA would reduce by 6,000 the number of people most heavily hit by airplane noise. That would be achieved by adding 35,000 people to the list of those who get low levels of aircraft noise today.
However, the study notes, "noise impact along the Potomac corridor would be generally unchanged within a distance of about five miles from the airport." That means that those people most heavily affected today - residents of Old Town Alexandria, Georgetown, [WORD ILLEGIBLE] and Crystal City, would find little relief from the alternative.
Under the present National flight patterns, planes take off and generally follow the [WORD ILLEGIBLE] northward for 10 miles or southward for five miles until they turn off forward their distinations. Under the FAA proposal, planes would be turned toward their destination in a much more random pattern. The FAA offered the alternative without recommending whether it should be adopted.
The greatest reductions in noise would occur in Montgomery County north of the Cabin John Bridge, according to the study. That area is where outbound jets turn toward their destinations and put on the the ground has spawned frequent vocal citizen protests from the Cabin John area. There would also be some reductions in the Prince George's County areas south of the Woodrew Wilson Bridge.
Increases in the noise would be noticed most prominenitly in the Springfield-Franconia area of Fairfax County.
Under current procedures, the study said, the average day-night aircraft noise burden exceeds 70 decibles for 16,144 people. Day-night noise average at that level is regarded as "highly annoying" to 40 per cent of those who hear it, according to one Environmental Protection Agency study.
The new proposals would reduce the number of people who get that much noise to 9,820.
Under present procedures, according to the study, 160,184 area residents - get a day-night average of 60 decibels or more. That number would increase to 195,588 under the alternative.
A day-night average of 60 decibels is regarded as "highly annoying" by only 20 per cent of the people who hear it, according to the FFA study.
THe day-night average, called [WORD ILLEGIBLE] is the unit FFA [WORD ILLEGIBLE] to measure the impact of aircraft noise. The [WORD ILLEGIBLE] [WORD ILLEGIBLE] impuses a penalty on fights at night and [WORD ILLEGIBLE] the administive impact on an individual of a number of flights.
Noise experts have learned that one loud jet [WORD ILLEGIBLE] is not terribly disturbing to most people, but that the level of [TEXT ILLEGIBLE]
The results of the study, detailed maps of where the plannes fly, and other data will be presented at the public meetings in May. COG will announce the dates and places for these meetings later.