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The Subcommittee on Aviation Hearing on Government and Industry Plans with respect to Stage 4 Commercial Aircraft

October, 2000


The number of people living in areas exposed to unacceptably high aircraft noise has dropped significantly since Deregulation. In 1978, 6 to 7 million people lived within areas exposed to average cumulative noise levels of 65 decibels (dB) or higher. Today, that number has fallen to approximately 500,000.1

Despite the impressive achievements of the aviation industry, aircraft noise remains one of the most difficult environmental challenges to commercial airport capacity expansion and airspace redesign in the United States. Often, community groups will block the construction of a new runway or the extension of an existing runway over the concern that any change in flight operations will negatively impact the quality of life in the surrounding areas.

Aircraft noise can be addressed in several ways, including modifying air traffic control procedures, land-use planning, noise mitigation (sound proofing), and reducing source noise produced by aircraft engines and airframes. This hearing will focus on government and industry efforts to reduce the aircraft source noise through new "Stage 4" noise standards.


Prior to 1968, the U.S. Federal government did not regulate aircraft noise. However, as concerns over the increasing impact of noise on communities near commercial airports grew, Congress authorized the Federal Aviation Administration (FAA) to regulate aircraft design and equipment to develop quieter airplanes. In 1969, FAA adopted its first standards for new designs of civil subsonic turbojet aircraft. These standards were intended to ensure that manufacturers would use the best available noise reduction technology when designing new aircraft engines and airframes.

In 1977, FAA adopted more stringent noise standards and applied them to all newly manufactured aircraft. Aircraft meeting the new standards were categorized as "Stage 3" aircraft; aircraft meeting the original 1969 standards were categorized as "Stage 2;" aircraft not meeting either set of standards were categorized as "Stage 1" aircraft. Stage 3 Noise Standards Stage 3 noise standards only apply to commercial subsonic jet aircraft over 75,000 pounds. These standards are generally based on aircraft weight and the number of engines. Under Stage 3, heavier aircraft that require more thrust are allowed to generate more noise than lighter aircraft. Different emission levels are also set for takeoff, landing, and sideline noise. Stage 3 standards do not apply to recreational aircraft, business jets, helicopters, turbo-props or supersonic aircraft (Concorde). Stage 3 standards may be met by various means. The most common means are: (1) manufacturing new aircraft to meet the restrictions; (2) modifying an existing Stage 2 engine by essentially placing a device on it that makes the engine quieter and brings it up to Stage 3 levels, a process known as "hushkitting;" (3) putting new, quieter Stage 3 engines on an existing Stage 2 aircraft, known as "re-engining;" or (4) imposing aircraft weight and flap restrictions that ensure that noise levels are at Stage 3 levels. In 1990, Congress passed the Aviation Noise Capacity Act of 1990 that required all commercial jets operating in the United States to be Stage 3 compliant by December 31, 1999, two years ahead of the international standard. Domestic airlines estimate that they spent roughly $100 billion to equip their fleets with Stage 3 compliant aircraft. Marginally Compliant Stage 3 Aircraft Despite the tremendous reductions in noise emissions brought about by the transition to Stage 3, communities near commercial airports continue to be concerned about aircraft noise. Much of the concern revolves around a small number of older Stage 3 compliant aircraft that create relatively high noise levels. These aircraft are often referred to as Marginally Compliant Aircraft. While no official definition of Marginally Compliant Aircraft exists, generally, the term refers to aircraft that fail to meet one or more of the Stage 3 requirements for takeoff, landings or sideline noise emissions, but are Stage 3 compliant because they meet the cumulative Stage 3 noise requirement. There are approximately 1100 aircraft (mainly modified DC-9s, 727s and older 737s) operating in the U.S. that can be characterized as Marginally Compliant. According to industry analysts, these aircraft account for 26 percent of domestic operations and produce 59 percent of all aircraft noise energy. ICAO and Stage 4 Noise Standards The International Civil Aviation Organization (ICAO) sets and administers international certification standards for aircraft. Once an aircraft is certified as having met ICAO standards, it may be used in any ICAO member country. ICAO certification gives operators and investors assurances of worldwide marketability for the normal life cycle of an aircraft. ICAO has promulgated international noise restrictions, similar to U.S. Stage 3 restrictions that are known as Chapter 3 noise restrictions; these restrictions become fully effective in 2002. The ICAO Committee on Aviation Environmental Protection2 (CAEP) has been working since 1998 to develop recommendations for new "Stage 4" noise stringency standards. In October 1999, CAEP narrowed down the list of possible stringency options to three possible options: (1) a cumulative reduction in aircraft noise emissions -8dB below Stage 3; (2) a cumulative reduction in aircraft noise emissions -11dB below Stage 3; and (3) a cumulative reduction in aircraft noise emissions -14dB below Stage 3. CAEP will analyze 26 different scenarios based on these three options. Later this month, the CAEP steering group will meet in Seattle, Washington to narrow down the possible scenarios to allow them to concentrate on 3 to 8 of the most promising scenarios. In January the CAEP will decide which of the remaining scenarios it will recommend to the ICAO Council. 3 Proponents of the –8dB option contend that it would provide aircraft manufactures the design flexibility necessary to address other important operational issues. The –8dB option would also provide aircraft owners and operators the greatest assurance that existing Stage 3 aircraft could be used to the full extent of their useful life. Detractors note that this option may be too lenient to appease noise sensitive communities and could result in regional noise stringency standards. Proponents of the –14dB option assert that the higher standard would encourage manufactures to develop innovative technologies to address noise emissions. Critics contend that such a standard is too far beyond current industry best practices to be practical and would force manufacturers to abandon current successful designs. CAEP is expected to reach consensus and will recommend a set of noise stringency standards to the ICAO Council. If the Council adopts the recommendations, then those standards will become the Stage 4 Standards for all ICAO member nations. The Council must then decide whether to recommend to the Assembly a phase-out of Stage 3 aircraft. The phase out of Stage 3 aircraft is the most controversial aspect of the Stage 4 process. Critics argue that such action would impose significant costs for aircraft owners, while producing limited benefits. Recent analysis shows that a phase-out would only remove 150,000 people worldwide from exposure to 65 dB noise levels at a cost of roughly $100 billion. They also assert a phase-out will exacerbate the current aircraft shortage and result in a reduction of service to smaller communities. Advocates of phasing out Marginally Compliant Stage 3 Aircraft claim that eliminating a small portion of existing fleets can eliminate the majority of aircraft noise. They also believe that it will reduce community opposition to airport capacity expansion. Article 84 Procedures Related to the adoption of the new Stage 4 standards is an Article 84 memorial pending before ICAO submitted by the U.S. against the European Union. In 1999, the European Union (EU) proposed adopting a regulation that would severely restrict the use of hushkitted and re-engined aircraft in Europe despite the fact that these aircraft meet all Stage 3 and Chapter 3 requirements. The proposed regulation violates universally recognized international obligations. Article 33 of the Chicago Convention mandates universal recognition of an airline's airworthiness certificate, where aircraft of the airlines’ flag meet all current ICAO standards. The proposed regulation also treats domestic and foreign operators differently in violation of the Convention’s nondiscrimination principle and potentially violates EU Member States’ bilateral air service agreements with the U.S. It unlawfully discriminates against U.S. operators by denying U.S. designated airlines the right to choose Chapter 3 compliant equipment best suited for its fleet. On March 14, 2000, the U.S. filed an Article 84 memorial with ICAO under the Chicago Convention asserting that the EU hushkit ban is not compliant with international standards. The memorial seeks relief from the proposed ban. After requesting two extensions, the EU filed a preliminary objection to the U.S. Article 84 memorial, claiming three points: · U.S. did not adequately engage in pre-filing negotiations; · U.S. companies failed to exhaust local remedies; and · Council lacks the authority to grant the requested relief. The U.S. will submit a rebuttal to each of these three points. On the first objection, the U.S. notes that it did in fact attempt to negotiate with the EU but failed to reach a resolution on this issue. On the second point, the U.S. contends that the EU Hushkit ban is a direct violation of the Chicago Convention and, thus, a direct injury to the United States. Lastly, the U.S. asserts that the final objection is inconsistent with Convention rules governing dispute resolution. The ICAO Council will hold a hearing on the EU preliminary objections in mid-October and is expected to issue an immediate ruling. If the Council finds in favor of the U.S., it will ask both parties to agree to negotiate a resolution. All previous disputes have been solved in this manner.

1 Unacceptably high aircraft noise is defined as average cumulative noise levels of 65 decibels or higher. The figures contained above are based on the population exposed to the average cumulative exposure of 65 decibels or higher based on the Day-Night Sound Level (dnl) method. 

2 CAEP consists of 18 member nations and 7 observer organizations. All CAEP proposals are based on consensus. 

3 The ICAO Council is the governing body of ICAO. It consists of 33 member nations.


The Honorable Edward W. Stimpson United States Ambassador Representative to the International Civil Aviation Organization

Ms. Louise Maillett Deputy Assistant Administrator for Policy, Planning, & International Affairs Federal Aviation Administration

The Honorable Gerald L. Baliles Chairman Coalition for a Global Standard on Aviation Noise


Mr. John Meenan Senior Vice President - Industry Policy Air Transport Association

Mr. Steven A. Alterman President Cargo Airline Association

Mr. David Z. Plavin President Airports Council International - North America

Mr. John Douglas President & CEO Aerospace Industry Association of America

Mr. Edward M. Bolen President & CEO General Aviation Manufactures Association

Mr. Ed Wytkind Executive Director Transportation Trades Department


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