Aircraft noise

The noise certification standards for the aircraft types in Table 3.1 are referred to as Chapters 3, 4 and 1424, and they became applicable from 1977, 2006 and 2018 respectively.

The noise contours in Figure 3.1. illustrate the differences on an operational basis between these noise certification standards. They represent three single aisle aircraft, with a maximum take-off mass (MTOM) of 75 tonnes, that just meet the limits of the Annex 16 Volume I Chapters and an aircraft that represents the state-of-the-art in-production single aisle aircraft technology. The footprints are areas that are exposed to noise levels greater than 80 dB during one landing and take-off, and indicate the reduction in aircraft noise from a technology/design perspective over time based on Annex 16 Volume I standards.

Figure 3.2. illustrates the historic trend in certified aircraft noise levels in terms of the cumulative25 margin to the Chapter 3 limits for the heaviest weight variants and maximum thrust rating for an aircraft type [5]  . Aircraft designs certified during the last 10 years (e.g. Boeing 737MAX, 787; Airbus A320neo, A350, A330neo) have a cumulative margin of 5 to 15 EPNdB below the latest Chapter 14 standard. The general trend over the last three years has seen marginal noise improvements to these aircraft designs.

Future developments in technology were considered by an Independent Experts Panel on behalf of the ICAO Committee on Aviation Environmental Protection (CAEP) in 2019 [6] . In terms of what leading edge technology could achieve in 2027 and 2037, they agreed on noise goals across four aircraft categories that included business jets (BJ), regional jets (RJ), single aisle (SA) and twin aisle (TA). Figure 3.2. also captures these data points which provide an indication as to how aircraft noise performance may evolve in the future.

24These are chapters of ICAO Annex 16 Volume I, a document that contains international aircraft noise standards.
25‘Cumulative margin’ is the sum of the individual margins (difference between certified noise level and noise limit) at each of the three Chapter 3 noise measurement points, expressed in Effective Perceived Noise deciBels (EPNdB).

In comparison to the section on certified data for specific products, this section provides insight into the noise performance of the in-service fleet registered in EU27+EFTA at the start of 2022. Figure 3.3. represents the average noise margin to the Chapter 3 limit for all aircraft built in a given year, and plotted according to the same categories as the certified data section.

As predicted in the last report, the average margin to the Chapter 3 limit for the single-aisle market has improved by about 10 EPNdB through the recent introduction of the Airbus A320neo and Boeing 737MAX aircraft. There has also been an equivalent reduction in the certified noise levels of regional jets due to the introduction of the Airbus A220 and the Embraer E2-series. Other categories show level or slightly rising noise levels in recent years.