Aircraft environmental standards

The aircraft types in 

 are certified against noise standards that are referred to as Chapters 3, 4 and 14,1 which became applicable from 1977, 2006 and 2018, respectively. The International Civil Aviation Organisation (ICAO) is currently reviewing the noise limits for these aircraft categories with the aim to create a new chapter that would become applicable in the next five years.

The ICAO also sets noise standards for light propeller- driven aircraft (Chapter 10) and helicopters (Chapters 8 and 11), whose noise limits were last updated in 1999 and 2002 respectively. Discussions have been initiated within the ICAO Committee on Aviation Environmental Protection (CAEP) noise technical working group to consider an update of these standards.

 illustrates the differences on an operational basis between the successive noise certification standards for each aircraft category in  . The circles represent the landing and take-off 80 dB noise footprint area for virtual aircraft that would just meet the limits of the Annex 16 Volume I Chapters and for an aircraft that represents the current state-of-the-art in its category.

Historic developments in certified aircraft noise levels are illustrated in 

 The figure represents the cumulative margin2 to the Chapter 3 limits for the heaviest weight variants and maximum thrust rating of aircraft types certified since 1990 
[5]
. The new data since the last report (e.g. Falcon 6X, Gulfstream GVIII-2, ATR 42/72 modified engine, A321 XLR) highlights the continued marginal improvements in noise levels since the 2010s. Jet aircraft continue to show cumulative margins of 8 to 15 EPNdB compared to the Chapter 14 limit. Margins for turboprops are lower, illustrating the slower development of noise reduction technology in this category. Overall,   confirms that technology is available across all categories to support an increase in noise stringency in the short term.

In 2019, an Independent Experts Panel established by the ICAO CAEP agreed on medium-term (2027) and long-term (2037) noise goals for leading edge technology 

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 These goals were set for each aircraft category (except turboprops) and are also represented in  . As the medium-term goal of 2027 approaches, there is an opportunity to review whether this has been met and to update the goals with later target years for them to remain relevant.

copter

While 

 contains certified noise levels of specific aircraft type designs  provides insight on the noise performance of the in-service European fleet registered in EU+EFTA at the start of 2024. The figure shows the trend over time of the average noise margin to the Chapter 3 limit for all aircraft built in a given year by aircraft category.

The average aircraft noise margins of regional, single- aisle and twin-aisle jets have flattened out over recent years. This suggests that new deliveries in these categories now consist entirely of aircraft types certified in the 2010s (e.g. Embraer ERJ E2, Airbus A320neo, A330neo, A350, Boeing 737Max, 787), which have a better noise performance than their predecessors. The average noise performance of the in-service fleet will continue to improve in the near to medium term as the older and noisier types still operating in Europe are gradually replaced. The rate of improvement will depend on the rate of new deliveries, which has been negatively affected by the COVID crisis and recent challenges in the supply chain to meet demand.

Since 1 January 2020, new aircraft types have to comply with a new type CO2 standard,3 although no aircraft has been certified against this standard as of the start of 2025. The focus thus far has been on certifying in-production aircraft types against a less stringent in-production CO2 standard as all aircraft have to be certified against this new requirement if they wish to continue to be produced beyond 1 January 2028.

 

As of the end of 2024, Airbus continues to be the only manufacturer to have certified in-production aircraft types, such as the A330-800neo and -900neo variants (

), and so the availability of certified CO2 data remains limited 
[7]
. In light of the approaching production cut-off deadline in 2028, certification of other aircraft types is ongoing by EASA and other regions of the world have also implemented the CO2 standard into their legislation with it becoming effective in the US on 16 April 2024. As per noise, the 2019 ICAO Independent Experts Panel goals for leading edge CO2 emissions performance in 2027 and 2037 would need to be reviewed soon for them to remain relevant.

icao

A revision of the ICAO Annex 16 standards for aircraft noise and CO2 emissions is currently being considered by the ICAO Committee on Aviation Environmental Protection (CAEP). This is the first time that CAEP standard setting has reviewed two standards at the same time in the form of an integrated dual stringency process taking into account design trade-offs at the aircraft level. The environmental benefits and associated costs of a broad range of options for more stringent new type standards have been assessed for an applicability date in the next 5 years. A recommendation by CAEP on new noise and CO2 limits is due at the CAEP/13 meeting in February 2025.

Considering the long-term development and in-service timescales of new aircraft types, it will be important to set an updated new type CO2 standard that will influence the fuel efficiency of future designs and effectively contribute to the ICAO Long-Term Aspirational Goal of net zero carbon emissions from international aviation by 2050 

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1 These are chapters of ICAO Annex 16 Volume I, which contain international aircraft noise standards.
2 ‘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). 3 ICAO Annex 16 Volume III contains international aircraft CO2 standards. The CO2 metric is a specific air range based metric (kg fuel per km flown in cruise) adjusted to take into account fuselage size.