As part of the CAEP/11 (2019) update to the ICAO Global Environmental Trends, a range of scenarios was developed for the assessment of future noise trends. The noise indicators used are the total contour area and population inside the yearly average day-night level (DNL) 55 dB contours of 315 airports worldwide, representing approximately 80% of the global traffic.
Scenario 1 (CAEP/11 Baseline) assumes no further aircraft technology or operational improvements after 2015. Scenarios 2, 3, and 4 (low, moderate, advanced technology) assume that the noise levels of all new aircraft delivered after 2015 will reduce at a rate of 0.1, 0.2, and 0.3 EPNdB per annum, respectively. For all scenarios, an additional 2% reduction is applied to the population counts inside the noise contours, to reﬂect a possible improvement of aircraft routing around airports.
Population counts for airports in the US, Europe, and Brazil rely on local census data. For all other airports, the NASA Gridded Population of the World, version 4 (GPW v4) was used.
Figure 1 shows the total 55 dB DNL noise contour area from 2010 to 2050. In 2015, this area was 14,400 square-kilometres, and the population inside that area was approximately 30 million people. By 2045, the area is expected to grow from 1.0 to 2.2 times, compared with 2015, depending on the technology scenario. Of note is that under the advanced aircraft technology scenario (Scenario 4), from about 2030 onwards, the total yearly average DNL contour area may no longer increase with an increase in traffic.
The long-term total DNL 55 dB contour area is lower by about 10%, compared with the prior trends projections. This decrease can be attributed to a combination of quieter aircraft entering the ﬂeet, as well as a reduction in the long-term traffic demand.
Figure 1 – Total Aircraft Noise Contour Area above 55 dB DNL for 315 airports, 2010 to 2050 .