International Civil Aviation Organization

World-wide CNS/ATM Systems

Implementation Conference

Rio de Janeiro, 11 – 15 May 1998

WW/IMP-WP/71

4/5/98

Item 1

Agenda Item 1:	Overview of CNS/ATM systems implementation

IMPACT OF CNS/ATM IMPROVEMENTS ON AVIATION EMISSIONS

(Presented by the United States)

Information Paper

Summary

The United States Federal Aviation Administration (FAA) has completed a preliminary assessment of potential fuel savings, and resulting benefits to the environment from reduced exhaust emissions, based on "free flight" capabilities to be provided by planned CNS/ATM improvements. New technologies and systems include datalink, digital communications, automatic dependent surveillance, satellite-based navigation and landing, and decision support tools. New capabilities to be provided by these technologies include reduced vertical separation, optimal climb and descent, wind-optimized direct routes, improved arrival and departure procedures, and more efficient traffic management practices. Estimates were developed for a projected fleet mix and projected traffic increases by phase of flight in the continental US, to the year 2015. Results for scheduled commercial operations indicate potential annual savings of nearly 10 billion pounds of fuel, over 200 million pounds of NOx, 186 million pounds of CO, and 58 million pounds of HC compared to what would have resulted without the improvements.

REFERENCES

FAA-APO-96-1

ICAO DOC 9687 (APA TFG)

RTCA DOC TFR-500

ICAO DOC 9646-AN/943

1.	Background

1.1	The ICAO Committee on Aviation Environmental Protection (CAEP) is charged with the development of international standards and recommended practices for measuring and controlling aircraft noise and engine emissions. Historically CAEP activities have been directed at improvements in methods for measuring gaseous emissions and at considering increases in stringency of the standards. More recently, the CAEP has expanded their consideration to include operational measures that have the potential to reduce aviation emissions, including CNS/ATM implementation.

1.2	Worldwide there is a considerable amount of unnecessary fuel burn and emissions released into the atmosphere due to air traffic control delays. Significant inefficiencies in the present air traffic system can impede the ongoing efforts to meet internationally agreed environmental objectives. Rapidly accelerating air traffic inefficiencies can result from projected growth. Increased emissions levels could compromise the ability of aviation interests to meet environmental obligations.

1.3	There is a general consensus between government and industry that there is an enormous potential for time and resource savings for future flights that are subject to less air traffic control (ATC) restrictions. Much of this consensus has been well documented in several RTCA task force reports and recommendations, and more recently, in the National Civil Aviation Review Commission Report. In support of this objective, the FAA is investing in improvements and new technologies for communications, navigation, surveillance, and air traffic management (CNS/ATM) for the national airspace system (NAS). These new capabilities and services are embodied in the government/industry concept of operations, which forms the basis for the introduction and integration of these technologies in the NAS architecture. This study was undertaken to determine what potential environmental improvements could be realized when the new concept of operations is put into practice.

2.	Discussion

2.1	It is expected that with new capabilities provided by new technologies, users of the NAS will enjoy better services, such as more wind-optimized trajectories, optimal climb and descent profiles, optimum cruise altitude and routing, and more efficient traffic operations. If the free flight paradigm results in lower fuel burn by users, a corollary benefit is less pollution--a clear environmental benefit that is often overlooked.

2.2	Planned CNS/ATM enhancements were assessed in the following categories:

Year	Technology	Capability
2005	Controller-pilot data link;

Automatic dependent surveillance;

Passive Final Approach Spacing Tool;

Traffic Management Advisor, single center;

Initial Conflict Probe;

Integrated Terminal Weather System

Reduced Vertical Separation (RVSM);

Optimal climb;

Wind-optimized above FL240;

Improved arrival/departure procedures;

Expedited taxi clearance

2010	Limited Digital Air/Ground Comm.;

GPS Wide area/Local area augmentation;

Active Final Approach Spacing Tool;

Terminal Automation Enhancements;

ADS-B ground stations

RVSM;

Optimal climb/descent;

Wind-optimized above 15,000 feet;

Improved arrival/departure procedures;

Enhanced surface management
2015	Digital Air/Ground communications;

Full Conflict Probe;

Traffic management decision support system	Cruise climb/descent;

Wind-optimized above 15,000 feet;

Acceptance rates for instrument conditions equal to visual;

Enhanced surface management

2.3	It was assumed that traffic would grow over the period in accordance with FAA forecasts, that the fleet would grow in accordance with ICAO projections, that all CNS/ATM enhancements outlined in the draft NAS Architecture Version 3.0 would be fully implemented, and that users would equip and take full advantage of new capabilities. Additionally, it was assumed that all planned airport improvements and near-term procedural improvements will be implemented as scheduled, and that adjustments will be made to the airspace as needed to accommodate optimal flight trajectories without overloading individual sectors.

2.4	Using 1996 as the base year, a baseline scenario (essentially a NAS with no modernization) consists of meeting future projected traffic growth and fleet mix with today's NAS capacity, adjusted for committed near-term airport and procedural enhancements. This baseline scenario was compared to an enhanced scenario that reflects implementation of CNS/ATM technologies as outlined in NAS Architecture Version 3.0. These two scenarios were compared for 2005, 2010, and 2015, representing time frames when key technologies and operational capabilities are introduced into the NAS to deliver new services to users. Simulated fuel/emission estimates of users operating in a NAS with no modernization versus what could be achieved with new capabilities were developed for each of the three time frames.

2.5	Comparison of the two scenarios indicates the CNS/ATM enhancements to the NAS have a potential annual fuel savings of nearly 10 billion pounds by the year 2015, which represents a savings of 6% from what would have been used without NAS modernization. The phase of flight above 3,000 feet accounts for 93% of the savings, with remaining savings occurring on the surface, and in transition. These fuel savings translate to an annual reduction in emissions of over 200 million pounds of oxides of nitrogen (NOx), 186 million pounds of carbon monoxide (CO), and 58 million pounds of unburned hydrocarbon (HC), representing savings of approximately 10%, 16%, and 19%, respectively.

Annual Savings in Millions of Pounds

Fuel	NOx	CO	HC
Above 3,000	9,332	200.6	173.2	55.7
Below 3,000	219	4.0	1.2	0.1
Surface	347	1.2	12.3	2.9
Total	9,897	205.8	186.7	58.7
% Savings	6.5%	10.7%	16.4%	19.6%

3.	Conclusions

3.1	The environmental consequence of air traffic system inefficiencies is increased fuel consumption and engine exhaust emissions. Without modernization of the air traffic system, these inefficiencies will grow as demand increases. Accelerated air traffic system modernization is necessary to maximize system operational efficiencies and thereby minimize environmental impacts.

3.2	A preliminary assessment has been conducted to estimate the potential fuel savings, and resulting benefits to the environment from reduced exhaust emissions, based on key technologies and operational capabilities to be provided by planned CNS/ATM improvements. Results of the preliminary assessment indicate that a significant reduction in fuel burn and aviation emissions can be achieved from the implementation of CNS/ATM. These results highlight the need to further consider operational measures in meeting internationally agreed environmental objectives.

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