Effects of Variable Vehicular Age and Classification Distributions in Mobile Source Modeling

Jackson Hole Airport is the only air carrier airport located entirely in a National Park, that being Grand Teton. Concerns over noise impacts led to an Airport/Park agreement setting allowable levels, restricting flights and flight paths, and calling for compliance monitoring in the noise sensitive areas. This study documented seven days of continuous noise level measurements made at four sites in the Park during four consecutive seasons in 1985-86. Individual sound exposure level measurements at B-737/200 jets, Swearingen Metro turboprops, and general aviation aircraft permitted computation of “aircraft-only” day/night levels (DNL) at each site for each day. Measurement of half-hourly average sound levels permitted computation of “total” DNL for comparisons. Results showed general compliance with the DNL limits, except when winds necessitated northerly departures, in which case a single B- 737 could cause an exceedance. There were no statistically significant differences in mean aircraft DNL for each site over the seasons, largely because of high variances. At the more remote sites, the total DNL was generally not established by airport activity, but by the 10-dB nighttime DNL penalty added to background levels generated by wind or water. The newer B- 737/300 aircraft, introduced to Jackson in the winter of 1986, were observed to be noticeably quieter on departure.