Aircraft noise

Jet and heavy4 propeller‑driven aircraft

These types of aircraft must comply with noise certification requirements and the associated noise limits referred to as Chapters 2, 3, 4, 5 and 145. These Chapters represent the increasingly stringent standards that have been agreed over time.

Figure 2.1 illustrates the differences between the noise certification standards with noise contours for four hypothetical 75-tonne jet aircraft that just meet the various Chapter limits. The contours represent areas that are exposed to noise levels greater than 80 dB during one landing and take-off, and can be seen to reduce over time from the first Chapter 2 standard applicable before 1977 to the latest Chapter 14 standard applicable in 2018.

Figure 2.2 presents an overview of the improvement in aircraft noise technology-design performance over time in terms of the cumulative6 margin to the Chapter 3 limits [23]. While recognising that aircraft are often sold in various configurations, Figure 2.2 only contains data for the heaviest weights and maximum engine thrust ratings. As the associated noise limits are higher for larger, heavier aircraft, this figure permits a comparison between the relative performance across a range of different aircraft types. The data has been reviewed, and new aircraft noise levels that have been certified by EASA during the 2016 to 2018 period have been added. Although these latest additions have a similar margin to aircraft from the period 2010 to 2015, they are still well below the applicable limit.

A view on future development goals that illustrate what the best technology could potentially achieve in 2020 and 2030, along with uncertainty bands, has been maintained in Figure 2.2. These are based on a review of noise technology by independent experts (IE) for the ICAO Committee on Aviation Environmental Protection that was performed between 2010 and 2013 [24]. The four categories cover most current jet aircraft families, except for the A380, which is added for information. An estimate is also provided for a small/medium range aircraft powered by two Counter-Rotating Open Rotor (CROR) engines which is expected to be able to just meet Chapter 14.


4 Maximum take-off mass is equal to or greater than 8,618 kg.
5 These are chapters of ICAO Annex 16 Volume I, a document that contains international aircraft noise standards.

Helicopters

Heavy and light helicopters have to meet the noise standards of Chapters 8 and 11 respectively. Figure 2.3 illustrates the noise levels over time with respect to the cumulative margin relative to the original Chapter 8 limit [23]. The data has been categorized according to the number of main rotor blades and type of tail rotor configuration (e.g. no tail rotor - NOTAR, Fenestron), as these represent important design characteristics that influence noise levels. Note that no new technology has been certified since the previous report.

Noise performance of the fleet registered in Europe

While previous sections look at certified data for specific products, this section presents information on the certified noise levels of aircraft that have actually been bought by airlines for use in operation. Figure 2.4 represents the average noise margin to the Chapter 3 limit for all aircraft built in a given year that have been registered in the EU or EFTA after 2000. In order to illustrate the trend of technology purchased over time, the data is plotted by build year and displayed in five categories as defined in Table 2.1.

Figure 2.4 shows that the margin to the Chapter 3 limit actually decreases for regional jets, despite the general trend of improved aircraft type certification noise levels in Figure 2.2. This decrease in margin is primarily due to the market purchasing larger models and heavier weight variants (e.g. shifting from ERJ-145 to EMB-175 regional jets). The introduction of the Bombardier CS100 and CS300 aircraft in 2016, subsequently renamed the Airbus A220-100 and -300, appears to be responsible for the improved margin in that year. While the single aisle trend has been relatively flat, the recent introduction of the re-engined Airbus A320neo and Boeing 737 MAX aircraft is expected to lead to future improvements in the margin. With respect to the twin-aisle category, the improvement in noise margin from 2008 is primarily associated with the introduction of the Boeing 787 and Airbus A350 aircraft types.