Aircraft certification for pollutant emissions

Since the 1980s, large aircraft engines have had to meet increasingly rigorous limits on the emission of pollutants. Accordingly, the part played by aviation in the overall pollution levels is relatively modest in Switzerland.

New environmental standards for aircraft

Like cars and oil-fired residential furnaces, aircraft emit pollutants that include not only gases but also carbon dioxide, which is harmless to humans but an agent in climate change, and also tiny particles of dust. Now ICAO has filled a gap in regulation, with the introduction of two new environmental standards for emissions by aircraft: one for carbon dioxide and one for fine particulate matter (FPM). Six years of technical and policy work went into the development of the new standards. Both new standards will come into force worldwide on 1 january 2020.

The CO2 standard

Carbon dioxide emissions are directly related to the amount of fuel consumed. As aircraft fuel is a major cost factor for airline operators, market forces alone have done much to make aircraft very economical in their fuel consumption (significantly less than 100 g CO2 per passenger kilometre). The new CO2 standard does two other important things. For new aircraft types, it sets the bar at the highest level currently achievable, with the requirement that all new large aircraft after 2020 must do better. Even more importantly, it addresses aircraft that are already in production today. Many current designs will be in operation for decades to come, and a large proportion does not currently meet the limits agreed in ICAO's environmental protection body. These aircraft will have until 2028 to achieve compliance or face a production stop. To achieve consensus on this relatively ambitious rule within ICAO's environmental protection body, it was necessary to grant a set of exceptions for a small number of aircraft types of non-Western origin, whose overall significance for carbon dioxide emissions is small in any event. For new small aircraft types with a maximum of 19 seats, whose emissions and potential for improvement are also modest, the standard is to be applicable from 2023.


The particulate matter standard

Modern large aircraft engine are required to comply with pollution limits, and their exhaust must be visually clean before they can be certified for operation. A new standard mandates additional certified testing for soot and other solid particles that are respirable or are suspected of being factors in climate change. Now, the dust particles that are generated by aircraft engines are unimaginably small and light. To assess them, therefore, it is necessary not just to weigh them but also to count them. Thus, obtaining a count of particles down to a diameter of less than one hundred-thousandth of a millimetre will be a powerful tool allowing aviation authorities to monitor these emissions. Switzerland played an important role in developing the demanding measurement procedures and associated standard (see also "Swiss innovation leads to a particulate matter standard for aircraft engines").

The particulate matter standard approved in ICAO's Committee on Aviation Environmental Protection governs all engines that are in production as of 1 January 2020. Since most of the engines currently being manufactured will still be in production beyond that time, engine manufacturers need to start testing these designs for compliance with the new standard and obtain the certifications on these basis, otherwise they will not be allowed to put them into service. In the last three years the first fine dust limits for mass and also the number of ultrafine particles emitteed have been developed based on standardized emission data collected from current enginges. ICAO's Committee on Aviation Environmental Protection approved these limits in february 2019. For new engines, a first stage in the reduction of particulate emissions will be enforced from 1.1.2023. The aviation sector is so far the only sector to introduce global limit values for ultrafine particulate emissions (in particular by limiting their number).


Further information