Airplane fueling

Expert view

Is this the new way for aviation to track carbon emissions?

May 7, 2021

Cirium is looking at practical and effective approaches to generating realistic emissions estimates.

Andrew Doyle, Cirium

By Andrew Doyle, Senior Director Market Development, Cirium

Hardly a day passes without fresh announcements surrounding aviation-related sustainability goals and initiatives designed to achieve them. But what the industry lacks is a reliable method for estimating the carbon emissions of ‘real world’ flights, which can also serve as the basis of a ‘single version of truth’ for consistent benchmarking.

Three principal challenges arise as a result:

  1. It is very difficult to make meaningful comparisons between aviation companies (compare ‘apples with apples’) because of the different methods of estimation being used across the industry
  2. Most carbon calculators have a high margin of error by design because – for example – they consider only simple great circle distances between airports or scheduled block times rather than actual duration, and they model aircraft types generically (ignoring latest engine variants or winglet equipage). This makes it very difficult to estimate the impact of investments in incremental weight reductions or technology improvements under real-world conditions
  3. Calculators designed to estimate the carbon footprint of an available seat that will fly on a future scheduled flight do not use reliable methods to project the actual aircraft configuration that will be used. This results in wide margins of error when serving individual travelers with predicted emissions data to help them make informed decisions at the booking stage

So how can the industry address these problems?

It could be argued that there are only two sources of ‘accurate’ emissions data: the airframe manufacturers because they design the aircraft, and the airlines because they put the fuel in them. However, the OEMs cannot be considered ‘neutral’ because fuel efficiency is a critical component of the competitiveness of their products in the marketplace, and they also do not necessarily have full visibility of how airlines configure, operate and maintain their aircraft post-delivery. Airlines, meanwhile, do not openly share their fuel consumption data on a flight-by-flight basis, but rather provide highly aggregated figures on a quarterly or more typically annual basis.

This is why Cirium is looking at practical and effective approaches to generating realistic emissions estimates. These include using publicly available data to model and calibrate aircraft performance characteristics and calculate fuel flow rate gate-to-gate, taking into account specific configurations by tail number.

With extensive fleet, schedule and flight status tracking sources like Cirium’s – integrated into a single data platform – it is possible to match aircraft attributes including age, operating empty weight, seat configuration, engine variant and winglet equipage against the taxi and flight times logged for each historical flight, meaning this method can be highly optimized.

To demonstrate the validity of this method, and benchmark our outputs against many different reported figures at both the detailed and aggregated levels, Cirium is developing a proof-of-concept (POC). A range of industry stakeholders will review the outputs of the POC and provide feedback on the methodology.

Key industry partners will ensure the estimates are as close to reality as possible through reviews and refinements to key operational variables. Examples include:

  • Aircraft operating empty weights, which tend to deviate from nominal manufacturer specifications due to airline customization
  • Typical load factors, and weights for passengers and baggage
  • Cargo payload on long-haul passenger flights
  • Engine efficiency deterioration

In parallel with optimizing this methodology to estimate emissions for historical flights using all available data points, Cirium is focusing on decorating future scheduled flights with CO2 figures, including down to the per-seat level. This involves analyzing how ‘cohorts’ of aircraft with common specifications have been deployed within an airline’s network historically, and marrying this with the data in the schedule to make the best possible prediction for the carbon footprint of a future flight.


Want to find out more? Contact us to explore how Cirium is supporting a more sustainable future in aviation.

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