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ICAO 9993

1st Edition, January 1, 2013

Complete Document

Continuous Climb Operations (CCO) Manual

Includes all amendments and changes through CRGD, November 28, 2013

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Description / Abstract:


Continuous climb operations (CCO) 

An aircraft's fuel efficiency in terms of fuel burned per kilometre flown in level flight increases with height. However, the fuel used in climbing to that altitude can be a significant part of the overall fuel used for the flight. Therefore, for any given route length, there is an optimum initial cruise flight level which will be dependent upon the aircraft type and mass, as well as on the meteorological conditions of the day. CCO is only one of the tools involved in a complete airspace design. Throughout the design process, CDO, CCO and other route modifications should all be considered.

CCO is an aircraft operating technique made possible by appropriate airspace and instrument procedure design and appropriate ATC clearances enabling the execution of a flight profile optimized to the performance of the aircraft, thereby reducing total fuel burn and emissions during the whole flight.

The optimum vertical profile takes the form of a continuously climbing path. Any non-optimal climb rate segments during the climb (other than during the noise abatement departure procedure (NADP)) to meet aircraft segregation requirements should be avoided. However, achieving optimal vertical profiles, while also enabling continuous descent operations (CDO) and maximizing the overall airport capacity, is critically dependent upon the airspace design and the level windows applied in the instrument flight procedure or ATC clearances. Such airspace designs need to take into account the optimum profiles for aircraft operating at the airport to ensure that the instrument procedure designs balance the need to avoid level and speed constraints that prevent efficient climb profiles with other aircraft operations in the airspace. Appropriate airspace design should be used to avoid, to the greatest extent possible, the need to resolve potential conflicts between the arriving and departing traffic flows through ATC level or speed constraints.

There is a difference in design philosophy between CCO and CDO. In surveillance environments, the CCO design should take into account that tactical changes to the flight path, initiated by ATC, may be desirable. In general, CDO aircraft should be left on the designed route and not given a vector "shortcut" because a CDO aircraft is already descending at flight idle power and thus descending at the steeper angle a shortcut requires may lead to an unstable approach. In contrast, ATC tactical shortcutting of a CCO departure to take advantage of observed aircraft climb performance is desirable because it saves both flight mileage and time. The potential for tactical shortcutting should be considered in any CCO design, as well as the fact that other flow restrictions potentially restrict the opportunity of ATC to provide tactical shortcuts. Section 1.3.2 provides several examples of designs that take advantage of tactical shortcutting by ATC.

It is of paramount importance that safety be maintained during all phases of flight — nothing in this guidance shall take precedence over the requirement for the safe operation and control of aircraft at all times. To avoid doubt, all recommendations are to be read as being "subject to the requirements of safety".