Sound Barriers

State transportation officials have agreed to look into noise issues at Van Nuys Airport by reviewing a crucial permit allowing the airport to continue operations even though it exceeds state noise-control limits.

Hearings on the airport’s permit, last held a decade ago, are expected to begin within six months. Results of the hearings, ordered by the state Department of Transportation, could impose new restrictions on airport operations.

The hearings on the variance--as the permit is called--were requested by two Valley legislators after repeated complaints from nearby residents about noisy jets and helicopters operating out of the airport, which is owned by the city of Los Angeles.

Van Nuys is one of eight airports in the state required to maintain a noise variance in order to operate, including LAX, Burbank Airport and San Francisco Airport. The busiest general aviation field in the world, Van Nuys is the only one of the eight that does not serve scheduled passenger flights.

Protesters have little chance of shutting down an airport because variances have always been granted, but they sometimes obtain compromises that can curtail certain activities.

Residents and businesses seeking to speak at the Van Nuys variance proceedings have until Friday to file a request with Caltrans. An appointed state administrative law judge will determine who may take part, said Dick Dyer, airport environmental specialist for Caltrans.

Participants, called intervenors, have the right to be represented by an attorney who can cross-examine witnesses during a variance hearing, which generally lasts two weeks. Findings by the judge are submitted to the chief of the division of aeronautics at Caltrans, officials said.

Van Nuys Airport was last granted a variance in February 1989 and issued an automatic extension in 1992, said airport spokeswoman Stacy Geere.

Anti-noise activists have repeatedly requested a new hearing, but their requests were ignored by airport officials, said a spokeswoman for Sen. Tom Hayden (D-Los Angeles). As a result, Hayden in March sent a request directly to Caltrans seeking a hearing. State Sen. Herschel Rosenthal (D-Los Angeles), whose district includes the airport, endorsed the request.

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A key issue among airport opponents will be an attempt to force out the noisiest aircraft at Van Nuys, the so-called Stage 2 jets, which are older and louder than newer, but far more expensive, Stage 3 aircraft.

Airport businesses argue that Stage 2 aircraft are economically important to the airport. They say Stage 2 aircraft, over time, will gradually wear out and be replaced by Stage 3 planes, so there is no need to adopt rules now.

Opponents point to airport statistics, which show that the number of noisier jets based at Van Nuys increased from 32 in 1992 to 51 last year, while newer, quieter jets have increased at only half that pace, from 50 five years ago to 58.

In the same period, the number of aircraft based at Van Nuys declined from 887 in 1992 to 758 last year. Much of the steady decline over the last two decades is attributed to a decreasing number of small single-engine piston aircraft.

“Airport issues across the country are getting a lot more attention than they ever have before,” said Sandy Brown, Hayden’s deputy chief of staff. “People who never spoke out before are really feeling the intrusion of aircraft noise on their daily lives. Pilots can fight it for only so long. It would be to everyone’s advantage to address the issues now.”

A variance can be granted if the greater public interest is served, even though noise exceeds state-mandated limits in a residential area. Factors to be weighed include the economic and technological feasibility of complying with the standards, the noise impact on the community, the value of services provided by the airport and whether the airport operator is making a good-faith attempt to meet the noise standards.

The key issue to be dealt with by the variance hearing involves the Community Noise Equivalent Level, a complicated, abstract method by which airport noise is measured under California law.

That level is the daily average of decibel readings recorded by monitoring stations near airports, weighted by a mathematical formula to reflect the fact that noise is more annoying at night. The results are used to draw imaginary lines around airports, a “noise footprint” marking boundaries of the areas where the average community noise reading reaches 65 decibels or more.

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The footprint is a statistical tool used to come to grips with aircraft noise, which fluctuates from moment to moment.

The real footprint shrinks to nothing when no aircraft are landing or taking off, and swells far beyond the average line when a noisy jet aircraft is climbing rapidly away from the airstrip. Human ears cannot detect any difference in noise on either side of the imaginary line.

The daily averages are further abstracted into a quarterly average, which is used to draw the footprints on which the state law is administered.

The goal of the law is to shrink the footprint to the point where no residences or schools are within it--only industrial, commercial, park and agricultural land.

The noise impact area at Van Nuys currently encompasses 57.6 acres and includes an estimated 1,053 dwelling units with a total of 2,468 residents.

In 1990, the footprint, drawn according to federal standards, covered 147 acres with 3,730 residents. The 1989 variance required that the size of the excessive-noise area not increase.

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Noise Footprint

The area inside the dotted line receives higher than the state-accepted noise level for neighborhoods adjacent to airports. The estimated 2,468 people living her receive a Community Noise Equivalent Level of 65 decibels or more. The state determines noise equivalent level by using a complex mathematical formula that gives more weight to nighttime noise.

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Residents in this area may participate in noise hearings.

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Size of noise impact area: 57.6 acres.

Estimated number of dwelling units: 1,053

Estimated number of people residing within the noise impact area: 2,448

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Aircraft Operations (by year)

1997: 537,470

1996: 526,433

1995: 526,177

1994: 485,584

1993: 514,320

1992: 520,468

1991: 509,620

1990: 528,110

1989: 507,003

1988: 468,779

1987: 476,627

Source: Van Nuys Operations