FAQs - Noise
Q.What is the purpose of JWA’s Access and Noise office?
A.The role of the JWA Access and Noise office is to monitor compliance with and enforce existing regulations regarding aircraft noise limits and operational restrictions. The Access and Noise office is charged with enforcement of two regulatory documents which govern noise and capacity issues at JWA: i) the Phase 2 Commercial Airline Access Plan and Regulation (Access Plan); and ii) the General Aviation Noise Ordinance (GANO). The Access Plan regulates commercial air carrier operations at JWA by placing limits on operational capacity, hours of operation, and noise levels at the County's ten (10) noise monitoring stations. The GANO details restrictions for general aviation (i.e. privately owned aircraft) operations. We also record, research and respond to over 2,000 noise complaints and requests for information from the community each year.
Q.How do you know if an aircraft exceeds the noise limits?
A.The Access and Noise staff utilizes a state-of-the-art noise monitoring system that enables them to track each of over 200,000 air carrier and general aviation operations that occur each year at JWA.
Ten (10) noise monitoring stations (NMS) transmit noise events to the Access and Noise Office, enabling the staff to analyze data on aircraft operations and identify if an aircraft has violated the noise limits.
Q.What happens if aircraft exceed the noise limits?
A.The regulations for enforcement of JWA’s noise limits are different for commercial and general aviation operators.
Commercial carriers must meet the noise limits at each of the Noise Monitoring Stations (NMS) on a quarterly-averaged basis. Exceeding the noise limits can result in penalties up to and including disqualifying the air carrier from operating that aircraft type for the specific class (i.e. Class A or Class E) at JWA.
General Aviation aircraft must meet the noise limits at each NMS on a single-event basis. However, if an aircraft exceeds the limits three (3) times within three (3) years, it can be denied use of JWA for three (3) years.
Q.What is the difference between “Class A” and “Class E” noise limits?
A.The “Class E” aircraft have more restrictive noise limits. Aircraft that operate in these two classes are not necessarily divided by aircraft type. Rather, aircraft weight is the primary factor, which is typically determined by the amount of fuel needed to reach a specific destination. For example, the Boeing 737 aircraft operates in both Class A and Class E categories. For short-haul destinations (e.g. S.F. Bay Area and Las Vegas) an aircraft can operate within the Class E noise limits; however, for long-haul destinations (e.g. Atlanta and Newark) the same aircraft might need to operate as a Class A. NOTE: The number of Class A average daily departures is limited by the Settlement Agreement to eighty-nine (89).
Q.How does the Airport ensure its noise measurements are accurate?
A.The accuracy of JWA’s noise measurements is accomplished through the use of precision noise measurement equipment, which meets the highest professional standard of accuracy in the acoustical engineering industry. Complementing this precision measurement equipment is the JWA practice of daily electronic calibration checks of all ten (10) noise monitoring stations, and annual laboratory certification of the field calibration equipment.
Q.What are the long-term measured noise values at each NMS?
A.Annual noise levels for the past 24 years are posted at here.
Q.What is Single Event Noise Exposure Level (SENEL) or Sound Exposure Level (SEL)?
A.The SENEL noise metric describes the total acoustical energy, in decibels, of an individual noise event compressed into a reference duration of one second. The SENEL noise level is typically five (5) to ten (10) dB higher than the maximum noise level (Lmax) for the same aircraft noise event. SENEL is the acoustical building block used to calculate cumulative noise exposure for an annual average day using the Community Noise Equivalent Level (CNEL). SENEL is the single-event metric used in the State of California, while SEL is the equivalent used by the federal government, the other forty-nine (49) states, and internationally.
Q.What is Community Noise Equivalent Level (CNEL)?
A.The CNEL is a twenty-four (24) hour, time-weighted energy average noise level based on the A-weighted decibel. It is a measure of the overall noise experienced during an entire day. The term “time-weighted” refers to the penalties attached to noise events occurring during certain sensitive time periods. In CNEL scale, noise occurring between the hours of 7:00 pm and 10:00 pm is penalized by approximately five (5) dB. This penalty accounts for the greater potential for noise to cause annoyance during these hours, as well as typically lower ambient noise levels during these hours. Noise that takes place during the night, from 10:00 pm to 7:00 am, is penalized by ten (10) dB. This penalty was selected to account for the higher sensitivity to noise in the night time and the expected further decrease in background noise levels that typically occurs in the night time. This means that an aircraft event occurring during the evening hours is treated as approximately three noise events for the purposes of calculating CNEL values. Each aircraft noise event occurring during the night time hours is treated as if ten (10) aircraft noise events had occurred.
The CNEL metric is used by the State of California to describe land use compatibility with respect to aircraft noise exposure. CNEL is also the noise metric standard defined in Title 21 of the California Code of Regulations, Airport Noise Standards.
The CNEL is calculated as:
CNEL = SENEL + 10 log (nDay + 5nEvening + 10nNight) - 49.4
|n = number of operations per time period
Day = 7:00 am to 7:00 pm
Evening = 7:00 pm to 10:00 pm
Night = 10:00 pm to 7:00 am
The CNEL metric is unique to California and is recognized by the federal government for noise measurement. Other states use the Day-Night Average Level (DNL). The key difference between these two metrics is that CNEL includes the additional penalty calculation for evening operations.
Q.Can people perceive a sound level difference of ≤ 3 dB?
A.A typical human listener would not perceive a difference between two sound levels occurring one after the other when the measured noise level difference was three (3) dB or less. Generally, in a community setting, it takes a noise level difference of more than 3 dB for nearly every listener to tell which noise event was louder, and this applies to two events that follow closely in time. A five (5) dB change is readily noticeable while a ten (10) dB change is judged by most people as a doubling (when the noise level is increased) or a halving (when the noise level is decreased) of the loudness of the sound.
Q. Do weather conditions affect aircraft noise and is it taken into consideration?
A.Weather variables can have an effect on the propagation of sound and the sound level recorded at the JWA noise monitoring stations. However, JWA staff have found from experience in the airport environs and from studies reported in professional literature that the effects of weather are difficult to predict and typically are very transient over time. From moment to moment, weather may influence sound levels at particular locations resulting in higher or lower intensities; however, these effects are small for short propagation distances and quite variable for large propagation distances. For this reason, the GANO makes no adjustment for the effects of weather. The maximum permitted noise limits specified in the GANO apply during all weather conditions and seasons; they represent the maximum noise level that is permitted to occur at each noise monitoring station at any time.
Q.Who controls aircraft flight paths?
A.The Federal Aviation Administration (FAA) and the pilot-in-command of each aircraft have sole jurisdiction and responsibility for flight paths. Accordingly, only the FAA has enforcement capability over these issues. The County of Orange, as the proprietor of JWA has no authority or control over aircraft in flight.
Q.Should departing aircraft fly down the middle of the Newport Bay?
A.The ideal flight path for commercial aircraft and private jets is to follow the Newport Bay out to the ocean. In actual practice, however, there is some dispersion or variation in the flight tracks of aircraft that can result in aircraft flying over the west or east side of the Newport Bay. There are several factors that contribute to this dispersion. One common reason relates to the fact that after aircraft depart the airport using a standard departure procedure, the aircraft execute a slight turn to align over the Newport Bay. The point where this turn is made is a key contributing factor to the aircraft’s path over the bay. If this turn is made a few seconds earlier or a few seconds later, the aircraft will be more to the east or west. Weather can also be a contributing factor, with winds aloft pushing the planes to one side or another.
Q.Where are departing aircraft supposed to fly once they’ve reached the coastline?
A.After aircraft depart JWA, they follow the Newport Bay to the coast. Those aircraft headed to destinations east of Las Vegas turn left over the ocean and then turn back inland at all points between Crystal Cove and Dana Point. If they make this turn at a more northerly point along the coast (e.g., Crystal Cove) they will cross closer to Aliso Viejo, while if they cross at more southerly points it will take them over South Laguna Beach or Laguna Niguel. Where this turn is made is purely a function of aircraft performance, other air traffic in the area and FAA’s direction with respect to aircraft spacing and separation for safety.
Q.Do commercial aircraft still execute a deep power cut-back on departures?
A.Some commercial aircraft operating at JWA do utilize special Noise Abatement Departure Procedures; a power cut-back, however, is not mandated by JWA. The commercial aircraft flown in the 1980s were generally noisier than today’s fleet. In the past, in order to meet JWA’s noise limits, those older aircraft had to depart at full power, climb as quickly as possible to gain altitude, and then reduce power until after reaching the coastline. The newer, quieter aircraft of today often do not need to execute as deep of a power cut-back (or at all) as was the case in the past.
In 1993, FAA issued Advisory Circular (AC) 91-53A in an effort to standardize Noise Abatement Departure Profiles (NADPs). This AC describes acceptable criteria for two safe departure profiles known as the “Close-in” and “Distant” NADPs. The procedures are based on the proximity of noise sensitive uses, like homes and schools, to the departure end of an airport runway. The AC provides general guidance for departure procedures at all commercial airports, not just JWA. Ultimately, airlines develop their own procedures according to their operational specifications for each aircraft type.
Q.Have recent departure procedures resulted in aircraft turning east before the coast?
A.No. JWA’s flight tracking system does not show commercial aircraft turning east before the coast. Residents can check flight tracks by using JWA’s flight tracking feature found at:
Those aircraft headed to destinations east of Las Vegas turn left over the ocean and then turn back inland at all points between Crystal Cove and Dana Point. Where this turn is made is purely a function of aircraft performance, other air traffic in the area and FAA direction with respect to aircraft spacing and separation for safety.
Q.Why do planes sometimes arrive from south of JWA?
A.Aircraft typically depart to the south and arrive from the north about 95% of the time due to the prevailing wind coming from the ocean. During certain weather conditions, such as the Santa Ana winds, the FAA will institute “reverse flow” operations in which aircraft arrive from the south and depart to the north. When aircraft arrive from the south, they do not follow the Newport Bay into the airport, but rather follow a path that is aligned with the runway.
When conditions are appropriate for changing the flow of the active runway, it is accomplished in a safe and efficient manner, and in close coordination with FAA Southern California TRACON. Numerous factors can impact the amount of time required to transition from one runway to another, including the number and location of inbound aircraft, system efficiency, and overall operational safety.
Q.Why are there “reverse flow” operations at times when there are no winds?
A.Runway usage is primarily dictated by the prevailing winds, although it’s important to note that winds aloft can vary in speed and direction from winds at ground level. With winds predominantly coming from the ocean, aircraft typically depart to the south and arrive from the north about 95% of the time with slight variations from year to year. However, during calm wind conditions and traffic permitting, it is not uncommon for FAA Air Traffic Control to approve a pilot's request to depart in the opposite direction. This is done in accordance with FAA Order JO 7110.65T.
Q.Should arriving aircraft follow the 55 Freeway?
A.Aircraft arriving into JWA follow the Instrument Landing System (ILS) navigation aid glide slope. The FAA explains that this glide slope is an imaginary line which projects straight out from Runway 20R at JWA, is elevated three (3) degrees above the runway, and extends to a distance approximately ten (10) miles north of the airport. The ILS glide slope crosses the intersection of the 5 Freeway and the 55 Freeway, and does not align with the 55 Freeway. The final approach segments are straight (except for some visual procedures) while the freeway is not. In fact, the ILS is well east of the 55 Freeway. The FAA further explains, and the airport’s independent observations confirm, that this alignment of the ILS has been unchanged for decades, and is the only precision approach into JWA. Visual approach paths are less precise, so aircraft navigating visually may over-fly a segment of the 55 Freeway, but there is no requirement for them to do so.
Q.What were the history and the circumstances at the Airport and in the community that led to the 1985 Settlement Agreement?
A.The introduction of the Boeing 737 and Douglas DC-9 jet aircraft into the commercial fleet in 1968 led to a strong adverse reaction to jet noise among nearby residents. Residents of the Upper Newport Bay area filed suit in 1968 against Orange County claiming damages caused by aircraft noise. Other citizens groups, as well as the City of Newport Beach (City), filed similar suits. In the early 1970’s, by means of lease restrictions with the air carriers, the County set a maximum number of average daily departures (ADD) for the Airport. During this same period the County developed a Master Plan for aircraft noise abatement designed to bring the airport into compliance with the California Noise Standards and prepared the Airport Noise Control and Land Use Compatibility Study and Environmental Impact Report (EIR) 232, which were approved and certified by the Board in February 1981. The Master Plan included installing the nation’s first aircraft noise monitoring system, limiting the average daily jet carrier departures, and setting a curfew for jet operations between 11:00 pm and 7:00 am. The City filed a lawsuit later joined by two community groups challenging the adequacy of the EIR. The judge’s order stopped all work on the Airport project in late 1981. In 1982, the County began a new Master Plan and a new EIR. The County and City continued to discuss administrative procedures and environmental protections until a compromise was reached in the form of the landmark Federal District Court-ordered Settlement Agreement in 1985.
In 2003, the original four signators approved a series of amendments to the Settlement Agreement that allowed for additional facilities and operational capacity and continued to provide environmental protections for the local community. Key provisions of the original agreement and the 2003 amendments are available at the following link:
Q.What is the Airport Noise and Capacity Act (ANCA) of 1990?
A.ANCA is a federal law enacted by Congress in 1990 to establish a national aviation noise policy. The purpose of this law is to constrain, at the federal level, the ability of local airport operators to restrict the use of their airports due to noise concerns. Operational restrictions like those established in the 1985 Settlement Agreement and enforced through the Access Plan and GANO are permitted only when an airport proprietor meets six specific and extremely difficult statutory criteria and receives approval from the Secretary of Transportation. Since the implementation of ANCA, no airport has successfully completed this review and approval process. However, the operational parameters in place at John Wayne Airport were “grandfathered” under ANCA and were permitted to remain in effect. If the County wanted to impose additional and/or more stringent restrictions than those currently in place at JWA, such amendments would be subject to ANCA.
The FAA reviewed the 2003 amendments to the 1985 Settlement Agreement, and concluded that the amendments are exempt from ANCA because they would not further reduce or limit aircraft operations.
Q.What is General Aviation and how is it regulated?
A. General aviation (GA) refers to all aircraft not operated by an airline or commercial carrier. General aviation aircraft can range in size from a single engine Cessna to a private business jet. These aircraft are allowed to operate at JWA 24 hours per day as long as they comply with the applicable noise limits and other regulations of the General Aviation Noise Ordinance (GANO).
Q.I hear aircraft noise after hours, why?
A.General aviation aircraft are permitted to operate at JWA 24 hours per day, as long as they meet the applicable noise limits and other regulations of the GANO which vary by day and night. Those aircraft which exceed the noise limits are issued notices of violations.
Commercial carriers occasionally operate beyond the permitted operating hours for a commercial carrier, on an approved “carrier curfew extension request”. Upon such a request a commercial carrier may be granted up to a total of 30 minutes beyond the permitted operating hours. This request is granted by the Operations division due to air traffic control issues, weather, mechanical problems, or an emergency substantially beyond the control of the operator.
Q.Are small aircraft allowed to perform stunts at low altitudes for long periods of time?
A.General aviation aircraft can operate 24 hours, as long as they are in compliance with the noise limits. Flight training is a legal practice. Training, which includes joy flying and aerobatic flying, is part of a normal procedure for small planes.
Q.What is the minimum altitude for helicopters?
A.According to FAA, helicopters have no minimum altitude requirements when weather, safety and other air traffic permit. See Federal Aviation Regulations (FAR) Part 91.119.
Q.Does JWA offer an acoustical insulation program?
A.The County’s Acoustical Insulation Program expired with the completion of the last insulated home on December 16, 2009. Participation was strictly voluntary and there was no cost to the property owners. Under federal and state law, eligibility for the program was limited to residences within the 65 dB CNEL contour.
Four hundred eighteen (418) residences in the Santa Ana Heights area have been sound attenuated and an avigation easement reserved through the County's Acoustical Insulation Program, which closed in December 2009. Nine (9) residences opted for acoustical insulation only. The County has also acquired 46 residences as part of the Purchase Assurance Program, many of which were acoustically insulated, an avigation easement reserved and then resold. Among these County acquired homes, those located within areas designated for Business Park uses were razed, avigation easements were reserved, and the land resold for compatible Business Park uses. A total of 473 residences in the Santa Ana Heights area have been purchased or otherwise made compatible through the County's Purchase Assurance and Acoustical Insulation Programs. Seventy-seven dwelling units in Santa Ana Heights remain in the "Noise Impacted Area" (within 65 dB CNEL contour).
A number of residents chose not to participate in either program. Specifically, 18 homeowners declined voluntary participation in the programs in writing. An additional 64 did not respond to invitations to participate.
Q.Are there any meetings we can attend to find out information about the airport noise program?
A.Quarterly meetings are hosted by the Access and Noise office which are held in the JWA administrative office at 3160 Airway Avenue in Costa Mesa. Meetings are open to the public, and attendees are welcome to participate. Meeting dates are posted on our website at: www.ocair.com/communityrelations/accessandnoise.aspx.