Aircraft Noise Information & FAQ

Glossary (.pdf)

Aircraft Noise Terminology (.pdf)

Aircraft Noise Fundamentals (35MB)  All you wish to know about aircraft noise. 

A comprehensive, but concise, report on the fundamentals of aircraft acoustics including the characteristics of sound, noise propagation, measurement terminology, effects of noise on humans, governing regulations, as well as noise program information at Oakland International Airport.  The document has been excerpted from the Airport Master Plan Update completed in 2006 and includes many excellent graphics to supplement the text and simplify comprehension.

Special Studies and Analytical Reports

Through the links below, you can open and review various aircraft noise technology reports that have been produced over the past several years.  The General National Reports are prepared by various governmental agencies and both national and international industry organizations and consultants and provide information to assist the reader in understanding the complex nature of aircraft noise management issues.  The Local Regional Reports and Studies are reports that were specifically produced by Port of Oakland staff or consultants or other local agencies.

General National Reports
Local Regional Reports and Studies

FAQ

What is a Noise Abatement Procedure?

I have a complaint/question about noise management, who should I contact?

Can the noise office change flight paths?

What happens when I submit a noise complaint?

What kind of information should a complaint convey and why?

Why do some aircraft seem louder than others?

What are Stage 1, Stage 2 and Stage 3 aircraft?

Who tells the pilots where and when to turn?

I was awakened last night by aircraft noise, what goes on at Oakland International Airport at night?

What is the difference between North Field and South Field?

Do I qualify for sound insulation?

Why do aircraft sound louder at night than they do during the day?

How big is Oakland International Airport?

Will noise increase as result of Oakland Airport expansion?

How does Oakland International Airport track and monitor flights?

When Do flight paths change?/How Do flight paths change?

What is the South East Plan?

When a plane dumps fuel, where does the fuel go? Does it land on my car or in somebody's swimming pool? Does it evaporate? Or does it mess up the ozone layer even more than it already is?

What is a Noise Abatement Procedure?
A noise abatement procedure is a recommended flight path aircraft follow to minimize noise over a populated area.  Because this is a recommended procedure, pilots may decline to follow it due to safety concerns or operating limitations. For some noise abatement procedures, a pilot must be able to see specific visual cues. If the visual cues are not visible, the pilot will not be able to safely follow the noise abatement procedure.  Other procedures rely on navigational equipment capabilities.

I have a complaint/question about noise management, who should I contact?
You can file a noise complaint at our Noise Complaints Page any time you want.  Our staff will investigate the possible cause of the complaint and notify you of what we find.  Alternatively, you can call our Noise Report hotline at (510) 563-6463 to voice your concerns.

Can the noise office change flight paths?
No. The FAA controls and regulates the airspace. Any change in departure or arrival flight paths must be approved and implemented by the FAA.  The noise office is here in large part to help communicate between the airport, FAA and local community.

What happens when I submit a noise complaint?
The noise office will log your complaint in the complaint database.  The Noise Management Office investigates all complaints by new callers and callers who desire specific information about noise events and aircraft activity.  When appropriate, staff follows up with aircraft operators and/or the FAA to investigate what action can be taken to minimize noise in the future.  Staff does not investigate every complaint made by frequent callers because they are often repetitive in nature and the staff may have previously spoken to the caller about their concerns.

What kind of information should a complaint convey and why?
The Noise Management Office documents noise complaints by obtaining information from the caller about the nature of the complaint, time of the occurrence and location of the caller’s residence.  Staff uses this information to determine the probable activity responsible for the complaint and, when requested, provides a report or a letter to the caller.  The letter or report may include the original complaint and flight track map(s), as well as a response that identifies the aircraft and activity responsible for the call (arrivals, departures, engine run-up, etc.), any available meteorological information (an important factor in aviation activities), and runways in use at the time of the call.  Staff may also be able to provide information on unusual noise events and, if appropriate, any action the Noise Office may take.

Why do some aircraft seem louder than others?
Aircraft operating at Oakland International Airport have a diverse range of noise levels. These noise levels primarily depend on the type of engine used by the aircraft, the size of the aircraft and whether the aircraft is taxiing on the airfield, landing or taking off. The newest so called "full Stage 3" aircraft tend to be the quietest aircraft in the fleet. Aircraft that were originally Stage 2 compliant but retrofitted to meet Stage 3 regulations tend to be the loudest.. Departures tend to be louder than arrivals since the pilot is forcing more power to the engine to achieve lift.

What are Stage 1, Stage 2 and Stage 3 aircraft?
This is a FAA-established classification system used to determine the noise level of an aircraft based on weight, number of engines and, occasionally, its passenger capacity. Aircraft may be certified as Stage 1, 2 or 3.

Stage 1 aircraft are the oldest and the noisiest and are not permitted to operate in the United States as commercial aircraft.

Stage 2 aircraft, over 75,000 pounds take-off weight, include the older Boeing 737-200, 727 and the DC-9. Stage 2 aircraft were required by law to be phased out of service by January 1, 2000.

Stage 3 aircraft meet current standards set by the FAA and generally are quieter. These aircraft include the Boeing 737-300, 757 and 767; the Airbus 320; and the MD 80/90. Some of the older Stage 2 aircraft were re-engined or "hushkitted" to meet the new Stage 3 standards.

Who tells the pilots where and when to turn?
Commercial pilots fly prescribed routes and general aviation pilots also fly prescribed routes as well as visual flight procedures (VFR) to and from Oakland International Airport as instructed by air traffic controllers. The FAA is responsible for managing Oakland’s airspace and for ensuring the safe and expeditious flow of traffic. The Port Of Oakland is responsible for operating and maintaining airport facilities and for ensuring that runways (and taxiways and other facilities) are in good working conditions, meet FAA regulations and are available for use.

I was awakened last night by aircraft noise, what goes on at Oakland International Airport at night?
Like most commercial airports in the US, Oakland International Airport operates 24 hours per day 365 days per year. There is no nighttime curfew at Oakland International Airport. However, the Port of Oakland, in coordination with the FAA, airport users and community representatives, has developed preferred nighttime aircraft procedures that help mitigate aircraft noise over residential areas.  Wind and weather permitting, these procedures try to keep aircrafts over the bay and away from residential areas as much as possible.

What is the difference between North Field and South Field?
South Field, which is defined as the Airport area south of Ron Cowan Parkway, is dominated by Passenger Facilities, including Terminals 1 and 2, and air cargo facilities, the largest of which is the FedEx Metroplex (their west coast hub operation).  North Field (the Airport area north of Ron Cowan Parkway) contains a variety of aviation land uses, the largest of which is general aviation, including aircraft hangars, ramps, and two fixed base operators, KaiserAir and Business Jet Center.  North Field also accommodates some air cargo facilities, including ABX Air / DHL and Ameriflight.

Do I qualify for sound insulation?
Oakland International Airport has finished its sound insulation program that it was overseeing in the city of Alameda.  Currently, Oakland International Airport is funding a sound insulation program in San Leandro, but the City of San Leandro is in charge of managing the program.  More information on the sound insulation program, including what noise levels qualify, can be found here.

Why do aircraft sound louder at night than they do during the day?
Nighttime noise events seem louder because the ambient noise is lower. More noise events may be noticed at night compared to daytime hours when there exists a higher ambient noise level.

How big is Oakland International Airport?
Oakland International Airport (OAK) is a primary commercial service airport with four runways: one primary air carrier runway at South Field (Runway 11-29) and three runways at North Field (Runway 9R-27L, Runway 9L-27R, and Runway 15-33).  The Airport is served by several passenger and cargo airlines.  In calendar year 2006, OAK accommodated approximately 14 million annual passengers (enplaning plus deplaning) and was the 34th busiest in the U.S. in terms of total passengers, according to Airports Council International-North America.

Will noise increase as result of Oakland Airport expansion?
The noise impact area for the Oakland Airport has decreased during the past decade and is expected to continue to decrease as a result of newer and quieter technology aircraft even with the planned expansion.  Development of the next generation of aircraft (Stage 4) is well underway and will bring quieter planes in the future.

How does Oakland International Airport track and monitor flights?
Our noise management office uses software called ANOMS, which stands for Airport Noise and Operations Monitoring System. This system collects noise data from 16 permanent and 4 portablecommunity monitoring sites in addition to flight track data from the FAA. It is the main tool used by the noise office to research complaints and to monitor noise abatement procedures and programs.

When Do flight paths change?/How Do flight paths change?/What is the South East Plan?
Winds in the Bay Area predominantly blow from the west to the east.  With winds from the west, the North Flow air traffic pattern (referred to as the “West Plan”) is in effect.  When wind direction in the Bay Area reverses and is from the southeast, the South Flow air traffic pattern (referred to as the “Southeast Plan”) is in effect.  The FAA alters the traffic pattern to the Southeast Plan when weather conditions such as winter storms shift the wind direction.  Historical data collected for the years 1999-2001 by the Airport Noise Management Office demonstrate that 91.5 percent of all arrivals and departures occur when the Airport is operating in the West Plan, which generally involves arrivals from the south and departures to the north.

Because arrival and departure patterns differ under the two plans, noise related to aircraft events is experienced differently depending on which plan is in effect.  Under West Plan conditions, areas to the north of the Airport experience noise related to departing aircraft, whereas areas to the south experience aircraft arrival noise.  Under the Southeast Plan, the opposite effects occur.

The Southeast Plan is perceived by the public as a dramatic change in the air traffic pattern and the change generates public reaction and aircraft noise complaints.  Below, are flight track maps displaying Bay Area air traffic patterns associated with Oakland International Airport (OAK), San Francisco International Airport (SFO), and San Jose International Airport (SJO) during the West Plan and the Southeast Plan. 

Southeast Plan air traffic routes are frequently implemented during winter months.  When these procedures are in place jets will fly over northern East Bay communities on arrival routes to both Oakland and San Francisco International Airport.  As displayed by the flight track map, SFO aircraft arrival tracks intersect with OAK aircraft arrival tracks in the north Bay Area.  In order to keep these aircraft safely separated, air traffic routes have been established to maintain the SFO arrivals above the OAK arrivals.  These routes have long been used and the Federal Aviation Administration is unable to make changes to these procedures. 

Southeast Plan Characterization Graphic

West Plan Characterization Graphic

When a plane dumps fuel, where does the fuel go? Does it land on my car or in somebody's swimming pool? Does it evaporate? Or does it mess up the ozone layer even more than it already is?

(From Wikipedia, the free encyclopedia. This article does not cite any references or sources. January 2008)

Fuel dumping from an aircraft is used to lighten the aircraft's weight in certain emergency situations. Fuel is typically jettisoned before a return to the airport shortly after takeoff, or before landing at an airport short of the intended destination.

Aircraft fuel dump

Aircraft have two major types of weight limits: the maximum structural takeoff weight and the maximum structural landing weight, with the maximum structural landing weight always being the lower of the two. This allows an aircraft on a normal, routine flight to take off at the higher weight, consume fuel en route, and arrive at a lower weight. (There are other variables involving takeoff and landing weights, but they are omitted from this discussion for the sake of simplicity.)

As jets began flying with U.S. airlines in the late 1950s and early 1960s, the FAA rule in effect at the time mandated that if the difference between an aircraft's maximum structural takeoff weight and its maximum structural landing weight was greater than 105%, the aircraft had to have a fuel dump system installed. Accordingly, aircraft such as the Boeing 707 and 727 and the Douglas DC-8 had fuel dump systems. Any of those aircraft needing to return to a takeoff airport above the maximum structural landing weight would simply jettison an amount of fuel sufficient to reduce the aircraft's total weight to below that maximum structural landing weight limit, and then land.

During the 1960s, Boeing introduced the 737, and Douglas the DC-9, the original models of each being for shorter routes; the 105% figure was not an issue, thus they had no fuel dump systems installed. During the 1960s and 1970s, both Boeing and Douglas "grew" their respective aircraft as far as operational capabilities were concerned via Pratt & Whitney's development of increasingly powerful variants of the JT8D engines that powered both aircraft series. Both aircraft were now capable of longer duration flights, with increased weight limits, and complying with the existing 105% rule became problematic due to the costs associated with adding a fuel dump system to aircraft in production. Considering the more powerful engines that had been developed, the FAA changed the rules to delete the 105% requirement, and FAR 25.1001 was enacted stating a jettison system was not required if the climb requirements of FAR 25.119 (Landing Climb) and FAR 25.121 (Approach Climb) could be met, assuming a 15-minute flight. In other words, for a go-around with full landing flaps and all engines operating, and at approach flap setting and one engine inoperative, respectively.

Since most twinjet airliners can meet these requirements, most aircraft of this type such as the Boeing 737 (all models), the DC-9/MD80 and Boeing 717, the A320 family and various regional jet ("RJ") aircraft do not have fuel dump systems installed. In the event of an emergency requiring a return to the departure airport, the aircraft circles nearby in order to consume fuel to get down to within the maximum structural landing weight limit, or if the situation demands it, simply lands overweight without delay. Modern aircraft are designed for possible overweight landings in mind, but this is not done except in cases of emergency, and various maintenance inspections are required afterwards. Many movies and TV news stories mistakenly assume that all aircraft can dump fuel, when in fact most cannot. In certain atmospheric conditions where the moisture content of the air is high, 737s (and other aircraft) flying at low altitudes sometimes leave a moisture trail that can come off the top of the wing, wingtips, or trailing edge flaps. Moisture trails coming off the trailing edge flaps can appear especially odd, since the moisture is being "spun" by aerodynamic forces. It's quite possible that some people observe these moisture trails and may think this is fuel being dumped, but it's just water vapor, and not fuel.

Longer-range twin jets such as the Boeing 767 and 777 and the Airbus A300, A310, and A330 may or may not have fuel dump systems, depending upon how the aircraft was ordered, since on some aircraft they are a customer option. Three- and four-engine jets like the Lockheed L-1011, McDonnell Douglas DC-10/MD-11, Boeing 747 and Airbus A340 usually have difficulty meeting the requirements of FAR 25.119 near maximum structural takeoff weight, so most of those have jettison systems. A Boeing 757 has no fuel dump capability as its maximum landing weight is similar to the maximum take-off weight.

Fuel dumping operations are coordinated with air traffic control, and precautions are taken to keep other aircraft clear of such areas. Fuel dumping is usually accomplished at a high enough altitude where the fuel will dissipate before reaching the ground. Fuel leaves the aircraft through a specific point on each wing, usually closer to the wingtips and further away from engines, and initially appears as more liquid than vapor.

The largest scale fuel dumping occurred on September 11, 2001, when many international flights were refused American airspace entry due to numerous hijacking incidents. Many of these international flights were fueled for travel well into the American interior. Many such flights were diverted into Canadian airspace, Newfoundland specifically, or instructed to return to their point of origin. For those mid-flight aircraft unable to land safely due to excessive fuel weight, dumping became necessary.

Below cited from: Aerospaceweb.org

Once released, the fuel trails behind the aircraft and creates a pattern that looks much like a contrail. Modern aviation fuel comes in many varieties but all are derivatives of kerosene. Kerosene evaporates rapidly in the atmosphere and very little typically survives in liquid form to reach the Earth's surface. The exact evaporative characteristics of dumped fuel depends on a number of factors like the altitude at which it was released, the atmospheric temperature, and the dumping pressure. Kerosene dumped at high altitude on a warm day tends to evaporate fastest.

The Federal Aviation Administration (FAA) sets requirements for when and how fuel dumping may occur in Order 7110.65P, Chapter 9, Section 5. This instruction stipulates that fuel can only be dumped above a minimum altitude of 2,000 ft (610 m), to improve its evaporation, and that a dumping aircraft must be separated from other air traffic by at least 5 miles (8 km). Air traffic controllers are also instructed to direct planes dumping fuel away from populated areas and over large bodies of water as much as possible. The same guidelines apply to military aircraft, and most air bases only permit fuel dumping in a specified area.

Despite these restrictions, environmental groups have expressed concern over the potential pollution implications of fuel dumping. It has been estimated that as much as 15 million pounds of fuel was released over the world's oceans by commercial and military aircraft during the 1990s. Although kerosene poses no danger to the ozone layer, it is a petroleum product that can impact water quality much like an oil or gasoline spill.
- answer by Jeff Scott, 2 October 2005