Noise Contours

The size of the noise contours is a reflection of the noise generated on the ground by each aircraft passing overhead and the number of aircraft that pass over in an average day. As a penalty, aircraft operations between the hours of 10:00 p.m. – 7:00 a.m. are weighted heavier with the automatic assignment of an hourly 10-decibel penalty in the computer model due to the intrusiveness of noise during late night hours and early mornings. These contours create lines labeled as DNL and are joined together at similar values in the noise modeling software that is approved by the FAA. The acronym DNL stands for Day-Night average sound Level and represents annualized values that are weighted and averaged over a 24-hour time period.

 

Modeled Year 2003

The shape of the noise contours represent the primary flight corridors that aircraft fly at RSW. Since, the northeast corridor is utilized approximately 80% of the time and aircraft are the noisiest on takeoffs rather than on landings, the contours are much wider and cover more ground to the northeast. At the southwest end, the contours are more elongated as this represents the operation of airplanes intercepting and lining-up with the extended runway centerline for landing. The contours are also narrower when compared to the northeast end as aircraft are some what quieter on landings.

 

While the FAA threshold limit of compatibility is 65 DNL, noise contours were developed to the limits of the 55 DNL to show areas that are considered to have moderate noise exposure. As shown in the exhibit below, the 70 to 65 DNL noise contours are located within airport property as outlined in yellow. Considering this, all recommended noise abatement operational procedures for RSW were approved as voluntary by the FAA. There are no noise sensitive uses located within the 65 DNL or above noise contours. Examples of noise sensitive uses are schools, residences, places of worship, hospitals, etc.

 

Composite 2020 Noise Contours

The composite noise contours shown in the attached exhibit include operations on both future parallel runways and represent the long-term noise exposure based on forecast aircraft operations expected at the airport. Similar to the Year 2003 noise exposure map, noise contours were also developed to the limits of the 55 DNL to show areas that will be considered to have moderate noise exposure