Trans World Airlines' Boeing 727 jets made more noise in Georgetown, Rosslyn and Old Town Alexandria during takeoffs in October than any other airline's 727 fleet, according to a new Federal Aviation Administration report.
The report is the first monthly collection of data taken from an FAA computer connected to noise monitors at key locations near flight paths at both National and Dulles International airports.
Georgetown, Old Town and Rosslyn, the three monitoring points closest to National airport also contain some of the metropolitan area's most vocal complainers about airport noise.
At Rosslyn, for example, TWA's 727 flights averaged 91.6 A-weighted decibels on takeoff. (An A-weighted decibel is a sound measurement abjusted to be particularly sensitive to the frequencies of human hearing). Northwest Orient's 727s averaged 81.9 decibels and the other airlines fell somewhere in between.
That means that Northwest, at Rossly, is about half as loud as TWA Each increase of 10 on the decibel scale represents a doubling of noise.
TWA was also higher, but by much less dramatic factors, at Georgetown and Old Town. Northwest was lowest at Old Town and second-lowest at Georgetown. At most other measureing points -- all farther away -- there was little to choose among the various carriers' performance.
Northwest Orient has for years insisted that its noise-abating takeoff procedure is more effective than anybody else's, and other airlines have generally disagreed.
The Northwest procedure, developed to calm a howling noise protest at Northwest's home airport in Minneapolis, involves a higher angle of climb immediately afther takeoff and an earlier thrust reduction than most airlines use. In theory the procedure places more of the loud take-off noise in the immediate vicinity of the airport and reduces the impact farther out.
The FAA, which has been encouraged for years to regulate noise-abating takeoff procedures, has published a non-binding advisory circular instead.
The FAA began its monitoring program in response to pressure from noise-weary citizens. Results will be used to test various takeoff and landing procedures and to "identify the performance of some carriers," as the FAA said yesterday. TWA has been notified of the results.
"We're reviewing the procedures -- climb out, et cetera -- and we plan to correct the problem," said John Corris of TWA.
The data for Dulles show, among other things, that the Concorde is a loud airplane, especially on takeoff -- but that had been proven some time ago.The Boeing 707 -- the old four-engine jet transport that ushered in the jet passenger age -- is almost twice as loud on arrival as the Boeing 727 and eqally as loud as the Concorde on arrival.