LA/Ontario International Airport (ONT) Part 150 NEM Update
Frequently Asked Questions
Below you will find answers to frequently asked questions about the Noise Exposure Map (NEM) update being conducted at LA/Ontario International Airport (ONT) in accordance with Title 14 of the Code of Federal Regulations Part 150. Title 14 noise and land use compatibility projects are often referred to as "14 CFR Part 150" or more simply "Part 150." The present update includes only the NEM portion of Part 150. As the NEM update project progresses and as other questions are received, we may add to this section to address questions of general interest.
The present project is an update to the NEM only whereas a full Part 150 project includes the Noise Compatibility Program (NCP). The Los Angeles World Airports (LAWA) is not updating the NCP at ONT at this time.
What is an NEM update?
When applying for a federal grant to implement noise compatibility measures at an airport, such as residential sound insulation programs, the Noise Exposure Map (NEM) is used to determine the area of eligibility. The NEM is most often thought of as a map that shows the noise exposure from aircraft operations using contours similar to topographical maps displaying ground elevations. An NEM update is a voluntary, in-depth re-evaluation of aircraft noise and land use compatibility as prescribed by the Federal Aviation Administration (FAA) in Part 150 regulations.
Over time, airport operations may change, technological advancements may reduce aircraft noise, and/or land uses may be altered to accommodate growth and development in the region. The current effort at ONT is an update to the NEM previously accepted by the FAA in 1991 and will be based on current (2015) and forecast (2020) aircraft operational activity at the airport. The FAA has provided funding assistance to complete this NEM update at ONT.
Why is the NEM being updated?
The FAA notified officials of the City of Ontario's Quiet Home Program (QHP), the aircraft noise mitigation program, that the QHP is no longer eligible for FAA noise mitigation grants until the NEM is updated and submitted by LAWA for FAA review and acceptance. The NEM is the primary vehicle used to determine eligibility for funding from both the FAA and LAWA to perform noise mitigation measures. Therefore, LAWA, as the airport operator, has initiated the process to update the NEM.
What will the ONT NEM update mean to residents near the airport?
What the NEM update means to residents can be determined only when all the data are analyzed. The current NEM used for noise mitigation eligibility near the airport is based on the 1995 forecast NEM, accepted by the FAA in 1991. The FAA currently requires NEMs to be updated at least every five years. Also, since 1995 there have been many changes to aircraft technology and aircraft operations. Therefore, it is necessary to determine what changes have occurred with respect to aircraft noise and incompatible land uses, based on current and updated forecast operations and aircraft types. It is too early to know how these changes will affect the resulting noise contours provided in the NEM, but the NEM update will likely result in a change to the eligibility area for noise mitigation programs where some residents, currently eligible in the 1995 NEM, may no longer be eligible for noise mitigation programs like the QHP.
How often must an NEM be updated?
The regulation requires that updates be conducted when there
is likely to have been a change in airport operations that would either: (1)
increase the yearly CNEL by 1.5 dB or greater in a land area which was formerly
compatible but is thereby made incompatible or in a land area which was
previously determined to be incompatible and whose incompatibility is
significantly increased, or (2) reduce noise by the same margin (CNEL reduction
of 1.5 dB or more) over existing incompatible uses. In both cases, the land areas to be
considered are those addressed by both the existing and forecast Noise Exposure
Maps on file with the FAA.
According to the recent update of the Airport Improvement
Program (AIP) Handbook, FAA Order 5100.38D, the FAA requires by policy that if
the FAA-accepted NEM used to document project eligibility (e.g., residential
sound insulation and land acquisition) is more than five years old, airport
sponsors are to confirm that the noise exposure map upon which noise
compatibility is based continues to be a reasonable representation of current
and/or forecast conditions at the airport.
How is noise exposure described in an NEM update?
Part 150 requires that airports describe noise exposure using
a measure of cumulative noise exposure over an entire calendar year, in terms
of a metric called the Day-Night Average Sound Level (DNL). In California, the
State Department of Transportation, Division of Aeronautics, uses a more
conservative substitute for the DNL metric known as the Community Noise
Equivalent Level (CNEL). While DNL is
the primary metric FAA uses to determine noise impacts, FAA accepts the CNEL metric
in California to assess noise effects.
DNL and CNEL are measures of cumulative noise
exposure over a 24-hour period, with adjustments to reflect the added
intrusiveness of noise during certain times of the day. DNL includes a single
adjustment period; each aircraft noise event at night (defined as 10 p.m. to 7
a.m.) is counted ten times as loud as a daytime event. CNEL adds a second
adjustment period; in addition to the nighttime adjustment, each aircraft noise
event in the evening (defined at 7 p.m. to 10 p.m.) is counted three times. The
nighttime adjustment is equivalent to increasing the noise levels during that
time interval by 10 dB. The evening adjustment is equivalent to increasing the
noise levels by 4.77 dB.
CNEL is the noise metric used in the ONT NEM update to
determine potential areas of noise annoyance and may be substituted for any DNL
How is noise exposure determined for the NEM update?
An NEM update requires computer-generated CNEL
estimates developed using the most current release of the FAA’s “Integrated
Noise Model” (INM). The CNEL must be
depicted in terms of equal-exposure noise contours (much as topographic maps
have contours of equal elevation). Part
150 requires that the 65, 70, and 75 dB CNEL contours be modeled and
depicted. Information on the noise model
can be found via the following link to the FAA’s website: INM.
CNEL values can also be measured. However, measurements are practical only for
obtaining CNEL values for relatively limited numbers of points. The FAA does not permit adjustments of the
noise modeling process using permanent or portable noise measurement monitors.
How are the forecasts
for aircraft operations developed?
The forecasts for
aircraft operations are prepared for separate market sectors: passenger
airline, cargo airline, and general aviation (GA). The 2015 base year forecasts reflect current
activity and recent trends, as well as views expressed by airport officials and
key operators at ONT regarding potential short-term changes in airport activity. In addition to these factors, the 2020
forecast takes into account longer-term trends including economic growth,
aviation industry strategic developments, and planned or likely changes in the
aircraft fleet mix. The research draws
heavily on aviation data compiled by the airport, the US Department of
Transportation, and the Federal Aviation Administration.
the NEM contours take into account changes to normal airport operations, such
as those that occur during Santa Ana weather conditions? Does the NEM include flights departing to the
east at night?
The development of the noise contours uses historical
aircraft flight track data over a recent 12-month period including aircraft
operations, runway use and identification of aircraft-specific flight
tracks. This approach captures and takes
into account all three of the normal aircraft operation flow conditions or
procedures, including Santa Ana weather conditions and easterly departures at
- Westerly flow – aircraft arrive from the east and
depart to the west on Runways 26L and 26R; predominant flow
- Easterly flow – aircraft arrive from the west and depart to
the east on Runways 8L and 8R; such as during Santa Ana conditions
- Contra flow – aircraft arrive from the east on Runways 26L
and 26R while departing to the east on Runways 8L and 8R; standard traffic
pattern between the hours of 10:00 pm and 7:00 am
Contra flow procedures are the standard operating conditions at ONT during the
nighttime hours stated above, there may be certain circumstances such as
adverse weather, aircraft safety, or airport maintenance that require a
deviation from this traffic flow, for example, departures to the west on
Runways 26L and 26R. These changes from
normal flow operations are also captured in the actual annual historical flight
track data, which are input into the FAA’s Integrated Noise Model to provide
the noise exposure results.
How is land use compatibility determined?
The FAA, other federal agencies, and several states have used
available data on community reaction to noise to create guidelines for
identifying the land uses that are compatible with specific noise exposure
levels – the more noise-sensitive the land use, the lower the noise exposure
should be in order to achieve compatibility.
The FAA guidelines, as defined in Part 150, state that all identified
land uses, even the more noise-sensitive ones (e.g., residential, schools,
places of worship, hospitals), normally are compatible with aircraft noise at
CNEL levels below 65 dB (Part
150, Appendix A, Table 1). These
noise/land use compatibility guidelines were adopted by LAWA and the local land
use control jurisdictions for the previous NEM and are again used for this
When was the existing NEM completed?
The NEM in existence today was completed along with the Noise
Compatibility Program (NCP). The NEM was
submitted to the FAA for acceptance in 1990.
Please use the following link to obtain more detailed information on the
previous Part 150: 1990 ONT Part 150 Study.
What is the NEM update schedule?
The NEM update began in the first quarter of 2014, and is
anticipated to be submitted to the FAA for acceptance in the third quarter of
2015. A more detailed schedule is posted
on the ONT Noise Exposure Map Update Home Page (ONT Part 150 NEM Update) which will be updated as appropriate. Dates, times, and locations of public involvement
opportunities will be announced on the Home Page of this website.
Who is involved in the NEM update and what are their roles
All interested parties are encouraged to participate in the
study. Please use the information provided
in the Public Comments section on the Home Page to submit any comments or
Several groups have pre-defined roles and responsibilities,
based on Part 150 regulatory requirements, as summarized below:
- Los Angeles World Airports (LAWA): As
the airport operator, LAWA has overall responsibility for all Part 150 related
actions at ONT.
- Federal Aviation Administration: FAA involvement includes participation by staff from several
- FAA Air Traffic Control Tower: The FAA tower staff
at ONT provides significant input in several areas, including: operational data
from their files. The tower staff also
may solicit input from other FAA air traffic control entities with which it
- FAA Los Angeles Airports District Office (ADO): The FAA’s Los Angeles ADO will review the Noise
Exposure Map submission for compliance with Part 150, notify LAWA of their
determinations, prepare a formal Letter of Acceptance of the NEMs, publish
related notices in the Federal Register, and provide opportunity for public
comment on the acceptance.
- Other FAA Offices and
Divisions: The ADO may solicit review and input on more
complex technical, regulatory, legal, or other matters from FAA’s Washington
headquarters or from other FAA divisions on a local or regional level.
LAWA has retained the services of Harris Miller
Miller & Hanson (HMMH), along with ICF International and CommuniQuest, to prepare
the NEM update.
Who is paying for the NEM update?
LAWA is paying for the NEM update with a combination of airport
revenue funds and a federal grant from the Airport Improvement Program (AIP). The FAA awarded LAWA an AIP grant that will
reimburse 80% of the NEM update cost. The
AIP is a federal program funded by fees collected from the users of the
National Airspace System. ONT and this project are not funded by
general taxpayer dollars.
Why hire outside consultants to conduct the NEM update?
The LA/Ontario International Airport is managed and operated
by a lean and efficient staff. Running
the Airport is a full-time job, with the highest priority placed on providing a
high level of customer service. An NEM update
requires significant time and special expertise in many technical and
regulatory areas. The NEM update is
being performed by a team of firms with nationally recognized capabilities and
experience in these areas, to ensure that the study is conducted in a
comprehensive, cost- and time-efficient manner, and with appropriate attention
to technical and regulatory requirements.
How can I participate in the NEM update?
interested parties are encouraged to participate in the process through the avenues
outlined on the Home Page of the project website (ONT NEM Part 150 Update). Dates, times, and
locations of public involvement opportunities will be announced on this
website. Please use the information in
the Public Comments section to submit comments or questions.