If air transport is responsible today for 2 to 3 % of greenhouse gas emissions (20 % are commonly attributed to automotive), it is often in the crosshair because it is very visible. There isn’t a day without news about a new aircraft being tested, a terror attempt on a flight, a new order for Airbus or Boeing, etc.

Following the example of other industries, aircraft fuel consumption has been significantly reduced (in the past 40 years, average fuel consumption per passenger decreased by 70 %). Today, aircraft fuel consumption is approximately 3.5 L per passenger per 100 km. This goes to explain why Airlines buy one aircraft over another to renew their fleet but also and especially to reduce their costs. Indeed, the latest aircraft consume less than their predecessors. As well as progress on the engines, there has also been progress on profiles, including the arrival of the wing tip ailerons, “winglets”. And in the case of the Airbus A380, savings are also achieved by the replacement of two flights by one thanks to the increased passenger capacity.

Fuel costs represent up to 30 % of a company’s spending. It’s easy to understand the efforts we have to make to reduce these costs for both a company already in operation and a start-up.

We will describe along these “Carnets De Vol” different economy measures already put in place or still on the drawing board. All the measures do not depend solely on the airlines. The Continuous Descent Approach is a good example of this.

The Continuous Descent Approach (flight efficiency)

CDA is a more ecological approach technique, also known as “green” landing.


Today, aircraft land in a stepped approach: decreased thrust to descend and increased thrust to level, and this cycle is repeated until touchdown. This approach is completely managed by air traffic controllers from the top of the “staircase” right through to the final alignment and landing:

In opposition, CDA allows the aircraft to descend with some engines idling approximately 40 miles or 65 km before landing. An increase in thrust is only needed 5 minutes before landing.

From the cruise altitude right through to the final segment of the approach, the aircraft FMS (Flight Management System) enables all of the approach to be done automatically.

The benefits are immediate both for the company and airports’ neighborhood. Indeed, fuel consumption is reduced, but the noise is also diminished because the engines are idling. We should also note that fuel consumption reduction is also increased thanks to the resulting time savings.

Figures indicate savings of over 150 000 tons / year of kerosene, equivalent to around 100 million Euros, and, at the same time, a reduction of 500 000 tons of CO2 per year and around 1 to 5 dB per flight. The Continuous Descent Approach is a requirement of the SESAR program to be applied at the end of 2013.

Today, CDA has not been put in operation anywhere in Europe or the United States as a standard approach. Tests are currently in progress at London, Stockholm, Amsterdam, Paris Orly, Strasbourg and Marseille airports. Regarding this last airport, I recommend reading the presentation of the French Civil Aviation: http://www.stac.aviation-civile.gouv.fr/manifestation/jt2009/comm/JT2009-STAC-Desc-continue.pdf.

For now, these tests are only applied during traffic off-peak periods.

It is also worth mentioning the initiative of the European Union SES (Single European Sky), Clean Sky, and FABEC (Functional Airspace Block Europe Central), as well as NextGen of the United States FAA who are all moving towards a generalization of this approach technique.

We can expect links between the Galileo program and SESAR project, especially since one of Galileo’s first applications is to enable take-offs and landings in difficult climatic conditions or on airports without adequate ground equipment. Finally, Galileo will also allow optimization of the schedule and routes.

It is indeed the Air Traffic Management for approach which is disrupted: Air Traffic Controllers have to acknowledge new procedures, new habits, and probably relinquish to the aircraft the control of its approach, but this is the price to pay for effective cost reduction.

Sources :

• “Getting air Traffic under Control” by Bryan Walsh (Time)
• “Sesar – Approche continue” by Burgi Hermann (Federal Assembly – Parliament Switzerland)
• CDA action plan (European Joint Industry)
• “Bénéfices des approches en descente continue (CDA) en matière de pollution atmosphérique” by Hélène Manzoni (STAC)
• http://www.eforefficiency.com