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 the TF#6 meeting (September 2019)

The 6th meeting of the European CCO / CDO TF took place at EUROCONTROL HQ on the 16-17th September 2019. A short summary of the status of ongoing work / outputs of the TF are detailed below.

European CCO / CDO Action Plan – The two key deliverables of the TF (namely the CCO / CDO Action Plan update and the CCO / CDO State of Play (SoP) report will now be combined into one key deliverable – the European CCO / CDO Action Plan. This new document will follow a structure, similar to other EUROCONTROL publications, that consists of a high level summary to pass the key messages, a main body of text (reflecting  the Action Plan update) and a set of appendices that focus on individual subject matter related to CCO / CDO (reflecting the old SoP document). This new structure will make the Plan easier to comprehend, more readable with less risk of duplicates and less risk of inconsistencies between the Action Plan and the SoP document. In addition, the appendices will allow a reader to go straight to the section of interest and will make it easier to maintain or/and to update content. The requirement for further specific content has been identified for the different appendices. Review leads have been identified for EACH separate appendix whilst ALL TF members are requested to review the main body of the report.

ATCO refresher training – The filming of 15 ATCO / Pilot TF members took place during the meeting to provide input material for the ATCO refresher training on aircraft energy management. In these videos, TF members discussed 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. The opportunity was also taken to fly and film a couple of scenarios in the Easyjet flight simulator depicting typical scenarios of how to optimise a CDO approach. The storyboard for the training has been developed by IANS who will be responsible for integrating the videos and interviews into the training material. It is expected that the refresher training will be available by the beginning of 2020.

Harmonised AIP material – Following the last TF meeting, an updated proposal for the harmonised location (ENR1.5 and AD2.21 / 2.22) and structure of AIP content on CCO / CDO was proposed to APDSG, shared with the EUROCONTROL SWIM team and discussed with several CFSP representatives. In addition, a proposal was made to APDSG to disseminate the information relating to harmonised AIP content via ERNIP Part 3. APDSG agreed with the benefits that can come from harmonised AIP material and approved the TF proposal. The next steps will be for the TF to propose harmonised textual content for the agreed structure - a generic text proposal under each heading of the proposed structure which can be adapted to local rules and regulations.

CCO / CDO Performance tables – A couple of glitches have been identified in the data stream, to be used to populate the performance which need to be investigated. The proposed reference trajectory will be validated by QAR data to be provided by Wizzair under an NDA. The TF agreed that the best way to present the performance table data(the basic functionality) is a simple bar chart which should a) be basic and free from clutter for easy understanding, b) allow comparison between airports / airlines, b) display an average value to identify performance above / below average. Once the performance tables are established then we can request feedback on any potential ways to optimise the visualisations. This will then help us to best visualise the enhanced functionalities of the performance tables e.g. breaking the data down to different periods of the day / time slices / level bands etc.

Engagement with airlines – Following the conclusions of the airline questionnaire to which >120 responses were received from ~60 airlines, the TF has identified that there is a need to more deeply with the airlines. The TF is looking for engagement from the top of the airline organisations to ensure that the messages cascade down from the top to ensure the correct messages permeate the airline structures. To that end, the TF is looking to populate 3 appendices in the Action Plan relating to best practices of airlines namely: flight crew training, airline SOPs and good practice CCO / CDO material, and airline CDO performance monitoring and pilot feedback. Engagement has commenced with IATA Geneva and we expect an IATA Observer to participate at the TF November meeting. In addition, engagement has taken place with EASA to discuss updates to Pilot training objectives on CCO / CDO, similar to those undertaken for ATCO training objectives.

ERNIP Plan update – The TF provided proposed updates to the ERNIP Part 1 review. The objective of the TF proposals was to ensure that optimisation of CCO / CDO together with assessing the environmental impacts of any future scenarios are an integral part of any airspace change proposal. The textual updates include specific text on the CCO / CDO sections with text aligning ERNIP with the text in the European CCO / CDO Action Plan. The proposals also include the addition of a set of good practice principles of airspace / procedure design to optimise CCO / CDO (developed from the conclusions of Europe-wide CDO studies and reviewed by TF members, APDSG and currently being reviewed by RNDSG). In addition, the proposals also include additional references for support of the airspace change process and other text proposals.

Informative Presentations – In addition to the ongoing work streams of the TF, the meeting welcomed informative presentations from the SESAR JU, Airbus, Jeppesen, LFV and Finavia. Jeppesen proposed to measure CCO and CDO for a small data set, based on FDR / QAR data, using the harmonised definitions, metrics and parameters for measurement defined by the Task Force.

CCO / CDO TF meeting #7 - The next meeting will take place on the 26-27th November 2019 at EUROCONTROL. At the next meeting, the TF expects to spend a considerable amount of time reviewing the European CCO / CDO Action Plan section by section with detailed inputs spent identifying any missing content. In addition, presentations are also expected from IATA, the ICAO ATMOPS Panel co-chair (discussion on phraseology) and the CFSP role in optimising CDO.

AOB – The TF will propose to NETOPS an extension of the TF mandate until the end of 2020. Based upon this proposal, two meeting are provisionally proposed for the first half of 2020. The dates for these meetings are: 17-18 March 2020 (Tues / Wed) and the 23-24 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.