Environmental Issues Aerospace Management

Module 1 - Module 4 Content

What is sound?

A physical phenomenon consisting of pressure fluctuations that travel through a medium and are sensed by the human ear.

What is noise?

Unwanted sound that can disturb routine activities.

Why is noise a major aviation concern?

It is often the predominant environmental concern of the public related to aviation.

What is the FAA’s primary noise metric?

Day Night Average Sound Level (DNL).

What noise metric can be used instead of DNL in California?

Community Noise Equivalent Level (CNEL).

What does the Airport and Airway Improvement Act of 1982 do?

Authorizes funding for noise mitigation and compatibility planning and establishes noise-related land use requirements for federally funded airports.

What did the Airport Noise and Capacity Act of 1990 mandate?

Phaseout of Stage 2 jets over 75,000 pounds and established noise/access requirements for Stage 2 and 3 aircraft.

What is the purpose of the Aviation Safety and Noise Abatement Act of 1979?

Directs the FAA to establish a single system for measuring noise, determining exposure, and identifying compatible land uses.

What does the 49 U.S.C. 47534 regulation prohibit after December 31, 2015?

Operating civil subsonic jet airplanes ≤75,000 pounds unless they meet Stage 3 noise levels.

What authority does the Control and Abatement of Aircraft Noise and Sonic Boom Act of 1968 give the FAA?

To prescribe standards for measuring aircraft noise and establish regulations to abate noise.

What is the Noise Control Act of 1972?

Amends the 1968 Act to consider public health and welfare and includes EPA in aircraft noise rulemaking.

Can state or local laws apply to noise from aviation projects?

Yes, state or local noise laws or ordinances may apply.

What are the general steps to describe the affected environment for noise?

Determine study area, identify noise-sensitive areas and land use, describe current noise conditions.

What is a noise sensitive area?

An area where noise interferes with normal activities associated with its use.

How is noise compatibility of land use determined?

By comparing aircraft DNL values at a site to land use compatibility guidelines.

What conclusion is drawn if noise and land use analysis shows no significant impact?

Usually, a similar conclusion can be drawn regarding land use in general.

What did the FICON report recommend regarding noise metrics?

DNL should continue as the primary metric for aircraft noise exposure.

When are supplemental noise analyses used?

To describe noise impacts for specific sensitive locations or situations and assist public understanding.

What should be included in NEPA documents regarding mitigation?

All existing or proposed measures to mitigate noise should be described.

What are common operational measures to mitigate aviation noise?

Preferential runway use and noise abatement flight procedures.

What are common mitigation measures related to land use?

Acquisition of land or interests, sound insulation of sensitive structures, and construction of noise barriers.

What are common construction mitigation measures for noise?

Proper mufflers for equipment and limiting machinery/truck noise in sensitive areas.

What is sound?

Pressure fluctuations that travel through a medium (such as air) and are sensed by the human ear.

What is noise?

Unwanted sound that can disturb routine activities.

What is a decibel (dB)?

A measure of sound pressure relative to a standard reference; uses a logarithmic scale.

How does the decibel scale work?

An increase of 10 dB represents a tenfold increase in sound level.

What is amplitude?

The intensity of sound waves, measured in decibels (dB).

What is frequency?

The pitch of sound; rate of sound pressure oscillations measured in Hertz (Hz).

What frequency range can humans hear?

20 Hz – 20,000 Hz.

Which frequencies are humans most sensitive to?

500 Hz – 8,000 Hz.

What is A-weighted sound level (dB(A))?

Noise measurement adjusted to human hearing sensitivity; filters out frequencies outside human hearing range.

What are psychological effects of noise?

Disruption of routine activities and communication, such as radio/TV listening, phone use, classrooms, and offices.

What is sentence intelligibility?

Percent of sentences transmitted and understood; non-native speakers are more sensitive.

What is the signal-to-noise ratio for steady noise?

15-18 dB above background; average adult voice is 50 dB; background should not exceed 35 dB.

According to WHO, what background noise level allows 100% speech intelligibility?

35 dB.

What is the speech interference level (SIL)?

Noise metric based on 500-2,000 Hz frequencies; goal

What is maximum noise level (Lmax)?

Maximum noise during an intermittent event; preferred alternative to SIL.

How much noise reduction occurs indoors on average?

26 dB.

What are physiological effects of noise?

Sleep interruption, stress, blood pressure changes, cardiovascular effects, birth weight, mortality rates.

What is Temporary Threshold Shift (TTS)?

Temporary hearing sensitivity reduction after loud noise exposure; usually recovers in quiet environment.

What is Permanent Threshold Shift (PTS)?

Permanent hearing loss from repeated high noise exposure without recovery time.

What factors influence individual annoyance?

Emotional (perceived preventability, activity, attitude, fear) and physical (neighborhood, time, season, predictability, control, exposure duration).

What is Day-Night Average Sound Level (DNL)?

Average noise level over 24 hours; night noise (10PM-7AM) weighted +10 dB for intrusiveness.

What are EPNL and its purpose?

Effective Perceived Noise Level; includes complex frequency weighting and penalties for pure tones causing increased annoyance.

What is FAA Stage 1 aircraft?

Loudest aircraft, takeoff/flyover/approach noise above Stage 2 limits; e.g., B-707, DC-8-20.

What is FAA Stage 2 aircraft?

Takeoff and approach noise limits for aircraft ≤75,000 lbs and >75,000 lbs; e.g., B-727, DC-9.

What is FAA Stage 3 aircraft?

Approximately 10 dB quieter than Stage 2; includes limits for takeoff, sideline, approach based on engines and weight; e.g., B737-8, B757, A320.

What is FAA Stage 4 aircraft?

Cumulative reduction of 10 dB from Stage 3; new measurement methods for approach, sideline, and takeoff noise.

What did the 1958 Federal Aviation Act establish?

FAA responsibility for aviation safety, navigation, and aircraft operations.

What authority did the 1968 Noise & Sonic Boom Act give FAA?

Broad noise abatement authority.

What does 14 CFR Part 36 cover?

Noise standards for aircraft type and airworthiness certification for aircraft built/operated after 1969.

What did the 1972 Federal Noise Control Act do?

Empowered EPA to impose noise restrictions on pre-1969 aircraft; responsibility for noise remained with FAA.

What is 14 CFR Part 91?

General Operating & Flight Rules; limited noise emissions on existing aircraft retroactively to Stage 1.

What problem arose with early noise regulations?

Air carriers used pre-1969 aircraft to avoid restrictions; forced into compliance by 1985.

What solutions existed for non-compliant aircraft?

Buy new compliant aircraft, re-engine older aircraft, or use hush kits.

What did the Aviation Safety & Noise Abatement Act of 1979 do?

Extended compliance waivers, provided financial incentives, encouraged noise exposure maps.

What was the goal of the Airport Noise & Capacity Act of 1990?

National phase-out of Stage 2 aircraft and creation of all Stage 3 fleet; reviewed airport noise and access restrictions.

What were Stage 2 phase-out deadlines?

2000: all Stage 2 aircraft forbidden; waivers allowed for 85% compliant fleet by 1999; full compliance by 2004.

What does the FAA Modernization & Reform Act of 2012 address?

Operating prohibition on certain aircraft ≤75,000 lbs not meeting Stage 3 noise requirements; temporary authorizations permitted.

What is acoustics?

Scientific study of sound and how the qualities of space affect sound transmission.

What is the yearly Day-Night Average Sound Level (DNL)?

Average aircraft sound levels at a location over a 24-hour period with +10 dB adjustment for noise occurring between 10PM–7AM.

What is the Community Noise Equivalent Level (CNEL)?

Alternative to DNL approved for FAA projects in California; adds +4.77 dB for noise between 7PM–10PM.

When is a noise analysis NOT required?

For projects involving Design Group I & II aircraft (

What is the Aera Equivalent Method (AEM)?

Mathematical procedure to estimate noise contour areas; suitable for overall increases in operations or larger aircraft without changes in flight tracks.

When is further noise analysis required after using AEM?

If DNL 65 dB contour area increases >17%, Aviation Environmental Design Tool (AEDT) must be used.

What is the Aviation Environmental Design Tool (AEDT)?

Computer modeling tool to assess aircraft performance including fuel, emissions, noise, and air quality; evaluates changes in DNL at various intervals.

What are alternative military noise screening tools?

NOISIEMAP (military bases), MR_NMAP (subsonic aircraft, MTR/MOA/SUA), PCBOOM (sonic boom modeling).

Why is managing airport noise challenging?

Airports are responsible for mitigation while aircraft operators generate noise; land use around airports controlled by state/local governments.

What strategies prevent new non-compatible developments?

Zoning, easements, and Transfer of Development Rights (TDR).

What is an easement?

A right to use property of another without owning it, generally obtained by purchase, condemnation, or dedication.

What is a Transfer of Development Rights (TDR)?

Landowners sell development rights from non-noise-compatible land in exchange for bonus rights on compatible land; voluntary and incentive-based.

When is acquisition of noise-impacted land used?

When few options exist for noise control; land can be repurposed for public use (maintenance, storage, floodways, reservoirs).

What are covenants in land acquisition?

Promises by a party to engage or refrain from conduct; function like contracts, not binding on future owners.

What options do airport operators have to control noise?

Denial of use, capacity limits, cumulative impact restrictions, certificated noise restrictions, single-event noise restrictions, noise abatement procedures, landing fees, noise barriers, and curfews.

What are noise abatement takeoff/approach procedures?

Runway selection, takeoff/landing profiles and power settings, approach/departure paths to reduce noise safely.

How can landing fees be used to control noise?

Base all or part of fees on aircraft noisiness or provide discounts/incentives for quieter aircraft.

What are common noise barriers?

Sound barriers, berms, “hush houses,” or building placement to block ground-based noise.

What are curfews in noise management?

Restrictions on flights during certain hours (often 10PM–7AM) based on noise thresholds; used as last resort due to economic impact.

What is soundproofing?

Modifying building structures to increase exterior-to-interior sound attenuation.

What are common soundproofing techniques for existing structures?

Sealing leaks, window replacement or adding second layer, acoustic vent baffling, adding insulation, two-panel walls, eliminating windows.

What are common soundproofing techniques for new structures?

Brick/concrete walls, staggered studs, insulation/fiberboard, attic insulation, baffling vents, separate roof construction, avoid exposed rafters, air conditioning, sealed mortar and joints.

Why is aviation significant in U.S. carbon pollution?

It is the largest unregulated source of carbon pollution in the U.S. and the most greenhouse gas-intensive mode of transportation.

How much of the average American household’s emissions come from air travel?

3.4%.

How much CO2 does one cross-country round-trip flight produce?

Equivalent to 10.5% of the average American’s annual carbon footprint.

What is air quality?

Measure of the condition of air expressed in ambient pollutant concentrations and their temporal and spatial distribution.

Why are air quality regulations important?

High pollutant concentrations can harm human health (especially children and elderly) and public welfare (crops, vegetation, buildings, property).

Which six pollutants are covered under NAAQS?

Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Ozone (O3), Particulate Matter (PM), Sulfur Dioxide (SO2), Lead (Pb).

What are common health effects of air pollution?

Respiratory disease, lung damage, impaired vision, reduced manual dexterity, learning impairment, brain/nerve damage, cancer, birth defects, premature death.

What are common symptoms of air pollution exposure?

Watery eyes, sore throat, wheezing, coughing, shortness of breath, asthma, chest pain, fatigue, impaired vision.

What flexibility do states have under the Clean Air Act?

They may set stricter standards than NAAQS and include additional pollutants.

How does EPA track NAAQS compliance?

Through air quality monitoring; areas designated as Attainment, Non-Attainment, or Maintenance.

What is a State Implementation Plan (SIP)?

Plan developed by states to inventory emissions, demonstrate attainment or maintenance of NAAQS, and establish emission budgets.

What happens if a state fails to submit an SIP?

EPA establishes a mandatory Federal Implementation Plan (FIP).

What is the purpose of the Conformity Rules?

Ensure federally funded projects do not adversely affect NAAQS progress or delay attainment.

What is the Transportation Conformity Rule?

Ensures highway, roadway, and transit projects comply with SIPs/NAAQS (40 CFR 93(A)).

What is the General Conformity Rule?

Ensures FAA and other federal projects do not cause new violations or worsen existing NAAQS violations (40 CFR 93(B)).

How is conformity evaluated?

Using an emissions analysis to determine project impacts.

What are “De Minimus” levels?

EPA thresholds for projects with negligible emissions, below which General Conformity Determination is not required.

Which projects are generally exempt from the General Conformity Rule?

Continuing/recurring activities, routine maintenance, routine operations, administrative actions, planning studies, normal material/personnel transport, civil/criminal enforcement.

What FAA actions are exempted under the General Conformity Rule?

Pavement marking, monitoring systems, non-runway pavement work, aircraft gate areas, lighting, terminal/concourse upgrades, HVAC systems, airport security, maintenance facilities, signage, commercial vehicle staging, low-emission tech, navigational aids.