Continuous climb and descent operations

Towards a flexible, optimum flight path that delivers major environmental and economic benefits.

Status of Task Force work flows following TF#7 meeting (November 2019)

The 7th meeting of the European CCO / CDO TF took place at EUROCONTROL HQ on the 26-27th November 2019. A short summary of the status of ongoing work / outputs of the TF are detailed below.

European CCO / CDO Action Plan (AP) – Since TF#6, detailed CDO AP reviews were received from the SJU, EUROCONTROL, skeyes, ENAIRE, ENAV, IATA, DFS, LFV, Lufthansa, Novair, NATS, Skyguide, IAA, Finavia and Ryanair. Comments from the UK CAA (via RNDSG) were also received together with specific content for the 3 airline appendices from Luxair, Wizzair, Vueling, IAG, Lufthansa, TAP, Finnair, British Airways, Ryanair, Norwegian, KLM and Easyjet. A proposal from the SESAR JU to promote the terms Optimised Descent Operations (ODO) / Optimised Climb Operations (OCO) as opposed to CCO and CDO was discussed. The latest version of the AP was reviewed, focusing on all major comments received from stakeholders. A long list of actions was identified that need to be completed in the next AP iteration (see section 4 for more details). These included a proposal that for tactical separation, where possible, priority should be given to the descending profile and the arrival flight, which is contrary to current guidance.

The next steps will be:

  • A new AP version will be shared by the end of January addressing all comments previously received and all outstanding actions;
  • By the end of February, all TF members will review the main part of the AP with individual TF members tasked to review individual appendices; and,
  • The Chairs will then create a further draft based on all comments received which will form the basis for the discussions to be held at the next TF meeting on the 4/5th March at EUROCONTROL

ATCO refresher training – Following the filming of the ATCO / Pilot TF members at TF#6 to discuss the meaning of predictability, the pilots perspective of flying open / closed STARs and the impact upon pilot / ATCO workload of low / high aircraft energy scenarios etc., the development of the training storyboard is still in the design phase. There are some potential challenges with converting the text content into something visual and/or interactive for an ATCO. Some HTML content has been completed but incorporating the videos has not yet started. IANS has reported that they are aiming to complete the material in Q2 in 2020, subject to the availability of resources.

Pilot training material – Two webexes were held with EASA to discuss the potential review and updating of EASA training objectives for pilots related to CDO. As the TF considers that training for Pilots regarding CCO/CDO should be included in all training, including ab-initio, a proposal to EASA was made to cover CCO / CDO-related material in the FCL (Flight Crew Licensing) and Operationally Suitable data (OSD) EASA regulations. This included initial pilot training for all pilot licenses and type rating training for PPL (Private Pilot Licence), CPL (Commercial PL) ATPL (Air Transport PL) and MPL (Multi-Crew PL). This will be followed up with EASA.

Harmonised AIP material – The proposal for harmonised AIP content relating to CCO/CDO (a placeholder (AIP location) and structure) was agreed by both APDSG and NETOPS although clarification is still required on which Part of ERNIP should disseminate the information concerning the harmonised location and content. For the proposed content, each section will contain short concise text based on current existing good practice AIP texts, clearly labelled as example text.

Engagement with airlines – Following the conclusions of the airline questionnaire to which >120 responses were received from ~60 airlines, the TF was looking for more focused engagement with the airline organisations to ensure that the correct messages cascade down from the top and completely permeate the airline structures. IATA gave a presentation on how the TF can better collaborate with IATA and the other airline associations. IATA proposed six actions where IATA can collaborate with the TF, five of which are currently being worked upon within the TF. In addition, the TF core team met with the IATA Regional Director following the TF#7 meeting and discussed targeting the correct people for TF engagement and the role of communications in getting our messages across.

Informative Presentations – In addition to the ongoing work streams of the TF, the meeting welcomed informative discussions, headed by the APDSG Chair, on Amendment 7A phraseology. The meeting also welcomed presentations from the CFSP Group on the CFSP’s role in optimising CDO and ENAC on the DSNA study for measuring CDO.

CCO / CDO TF meeting #8 – Following several scheduling conflicts, the next meeting is proposed for the 04/05th March (Wednesday / Thursday) at EUROCONTROL, subject to final confirmation by the end of January. This meeting will likely focus entirely on the Action Plan review and for that reason we would like to make a specific request to stakeholder representatives to participate at that meeting. An agenda will be distributed as soon as the meeting is confirmed.

AOB – NETOPS has agreed an extension of the TF mandate until the end of 2020. Based upon this proposal, the next meeting following the March meeting is currently proposed for the 23-24th June 2020 (Tues / Wed).

Continuous Climb and Descent Operations (CCOs and CDOs) are aircraft operating techniques enabled by airspace design, instrument procedure design and facilitated by air traffic control (ATC). CCO and CDO allow aircraft to follow a flexible, optimum flight path that delivers major environmental and economic benefits - reduced fuel burn, gaseous emissions, noise and fuel costs - without any adverse effect on safety.

CCO and CDO operations allow arriving or departing aircraft to descend or climb continuously, to the greatest extent possible. Aircraft applying CCO employ optimum climb engine thrust and climb speeds until reaching their cruising levels. With CDO, aircraft employ minimum engine thrust, ideally from top of descent and in a low drag configuration, prior to the final approach fix. Employment of these techniques reduces intermediate level-offs and results in time being spent at more fuel-efficient higher cruising levels, hence significantly reducing fuel burn and lowering emissions and fuel costs (see ICAO Doc 9993 and ICAO Doc 9931).

340,000 tons

fuel savings (1 million+ tonnes CO2)

+ € 150 M.


1-5 dB

noise reduction

Implementation support

We, at EUROCONTROL, support CCO and CDO deployment. A dedicated team works with stakeholders (ANSPs, aircraft manufacturers and aviation industry associations such as IATA, A4E, AIRE, EBAA, ERA, ACI and CANSO) to measure and maximise the benefits achievable in the current ATM framework. The team also supports the facilitation of a more advanced CCO and CDO concept that will result from deploying future ATM tools and procedures. A guide to implementing continuous descent is available. 


Deployment of optimised CCO and CDO throughout Europe will be beneficial to all European ATM system stakeholders and will help the network to address the environmental challenges it faces.

In 2018, EUROCONTROL conducted an ECAC-wide CCO and CDO analysis using 2017 traffic data, in order to estimate the potential network benefits of optimising the CCO and CDO in terms of fuel savings, emissions reduction and fuel costs.

 For CCO, the study concluded that 94% of flights in ECAC currently fly CCO to FL (Flight Level) 100 while 74% fly a full CCO to Top of Climb (ToC).

 For those flights currently flying non-CCO profiles, the average time in level flight to the ToC was 168 seconds with per-flight savings estimated at 15kg fuel/48kg CO2/7EUR. Across the network, this would result in a potential average per-departure saving of 4.3kg fuel/13.7kg CO2/~2€

 For CDO, the study concluded that 41% of flights fly CDO from FL75 (the top of the noise CDO) while only 24% fly a CDO from Top of Descent (ToD – the top of the fuel CDO). 

For those flights currently flying non-CDO profiles, the average time in level flight from the ToD was 217 seconds, with per-flight savings estimated at 46kg fuel/145kg CO2/20EUR. Across the network, this would result in a potential average per-arrival saving of 35kg fuel/110kg CO2/15€.

 The ECAC-wide study identified two main conclusions:

  • The results indicate that in Europe the potential savings from optimising CCO and CDO are up to 340,000 tonnes fuel/year, (1.1M tonnes CO2/150M EUR) *; 
  • The potential fuel saving benefits from CDO are in the region of x10 those from CCO.

(*) It should be noted that the achievement of 100% CCO and CDO across the European network may not be possible for a number of reasons, such as safety (i.e. the need to keep aircraft separated by a certain distance or time), weather, capacity or ATCO workload, all of which may be considered as interdependencies, while small inefficiencies in the system are required to operate a flexible and operationally efficient network.

What are Continuous Climb and Descent Operations (CCO and CDO)?

What can air travel industry do to reduce noise pollution?

The European CCO and CDO Task Force

Historically in Europe, the implementation of CCO and CDO operations has been encouraged on an ‘as-much-as-you-can’ basis while, until recently, there has been no harmonised definition of what actually constitutes a CCO or CDO operation. 
In addition, there has been no assessment of the potential network-wide benefits that could be realised by optimal CCO and CDO operations.

In 2015, a task force of European ATM stakeholders was created with the objective of agreeing harmonised definitions, metrics and parameters to measure CCO and CDO operations in Europe. The resulting harmonised definitions, metrics and parameters agreed by the Task Force are recommended to be used by any European ATM stakeholder for the measurement of CCO, CDO or vertical flight efficiency performance in order to enable harmonisation at international level.

The work of the Task Force is ongoing and is expected to be completed by 2019 with the delivery of an updated CDO Action Plan document and a “State of Play’ document on CCO/CDO. 
More information will be detailed on the website once it becomes available.