Aircraft Noise

Aircraft Noise Modeling

Aircraft noise modeling is primarily used for Airport Noise Compatibility Planning under Federal Aviation Regulation Part 150 and for Environmental Assessments and Environmental Impact Studies under Federal Aviation Administration Order 1050.

Noise modeling is accomplished through the use of various computer programs which evaluate aircraft noise impacts around airports. These noise modeling programs are based on a set of algorithms that estimate noise based on several environmental factors. Noise modeling evaluates noise output based upon either noise exposure, maximum noise levels or models may be time-based.

Noise modeling is used to assess current aircraft noise impacts around airports or heliports, to assess changes in noise impacts resulting from new or extended runways or runway configurations, to evaluate noise impacts from new operational procedures, and to assess noise impacts from new operational procedures.

Airport Noise Abatement Procedures

Noise abatement procedures are generally designed by local airports in conjunction with the Federal Aviation Administration’s air traffic control facilities managing air traffic at larger airports to minimize noise exposure to residential areas while propagating flight safety.

Noise abatement procedures may be a combination of formal and informal procedures such as radar vector departures, curfew hours, high and tight traffic patterns, avoidance of noise-sensitive areas, and aircraft manufacturers and air carrier noise practices such as using reduced power settings on departure. Profile docents into major airports where a flight crew may limit power-up events can also be effective in expanding noise abatement procedures for noise-sensitive residential areas.

Some formal noise abatement procedures include radar vector departures designed to route aircraft away from noise-sensitive residential areas, however, since there is normally no required distance from the airport before the air traffic controller can turn an aircraft, this type of noise abatement procedure has limited success

Voluntary noise abatement procedures are not normally effective. Airport entities often try to cover their lack of specific action to protect noise-sensitive areas by claiming that they have no authority because the pilot is always the ultimate authority. Even though a pilot has the “ultimate authority” for the operations of his aircraft, Federal Aviation Regulations still apply, and when one is broken, the pilot has to justify his or her actions.

Taking / Inverse Condemnation

Taking is an action by a government that deprives a person of private real or imagined personal property without the payment of just compensation. As related to aviation, a government could affect this taking by regulating the use of the property to such a degree that it no longer has any economically viable use.

A term similar to taking is “inverse condemnation” which is a legal procedure to obtain compensation when a property interest has been taken or diminished in value by a government activity.

According to the Fifth Amendment to the Constitution, the taking of private real or personal property (taking/inverse condemnation) for public use by the government requires due process of law and just compensation to the owner for the value of the property taken.

For example, A certain Corporation plans to construct a 60-foot office building near a public airport, notifies the FAA, and subsequently receives a Determination of No Hazard at the 60-foot height. Before the corporation can begin construction, the airport authority decides to lengthen the airport’s runway and notifies the corporation that its office building will now be restricted to 40 feet, seriously diminishing the economic viability of the project. The corporation may sue for inverse condemnation (a taking) and if successful may force the airport authority to provide them with just compensation.

Williams Aviation Consultants have considerable expertise and experience in determining maximum allowable heights of structures in the vicinity of airports based on the provisions of FAR Part 77 and the U.S. Standard for Terminal Instrument Procedures, has assisted attorneys and provided expert testimony in regard to determinations of value and just compensation based on takings and inverse condemnation.

A determination of maximum allowable height serves as the foundation for determining the value of a structure and therefore just compensation to the owner for the value of the property taken.

Airport Noise Contours

Noise contour lines are continuous lines on a map that represents equal levels of noise exposure.

Noise lessons from the innermost area within a contour line outward. Future noise contour lines may combine projected runway utilization percentages, fleet mix, flight corridors, and projected noise exposure including the use of a planned additional parallel runways.

The least severe noise exposure occurs outside the 55 DNL contour line, the level at which the Federal Aviation Administration (FAA) describes noise exposure as minimal. The FAA considers residential development and other noise-sensitive land uses as acceptable in these areas and recommends no special noise-control measures.

Noise exposure is regarded as moderate between the 55 DNL and 65 DNL noise contour lines, and the FAA recommends that land-use controls be considered. Noise exposure is regarded as significant above the 65 DNL noise contour line and the FAA recommends that land-use controls be implemented.

Airport Noise Attenuation

Noise attenuation is effective in curtailing noise complaints from residents and property owners. In areas where there are recognized noise impacts (65 DNL or above) soundproofing and other noise attenuation measures can be effective.

Normal construction methods and codes normally provide an indoor noise level reduction to 45 dB or less which is well within the guidelines for noise reduction in areas impacted by noise.

The United States Congress authorized the Federal Aviation Administration in 1979 to devise technology and programs for the attenuation of noise for homes around airports. The program has been effective for attenuation in school and residential interiors.

The principal technology is a computer model which simulates the dissemination of aircraft noise and its incursion into buildings. Differing aircraft types, flight routes, and local weather can be evaluated along with alternative building reconstruction strategies such as reroofing, window upgrades, fireplace noise suppression, caulking of seams, and other retrofitting measures for noise attenuation.

Avigation Easements

AA AC 150/5100-17 CHG 6 states that where it is determined that fee title is not necessary, an avigation easement may be used to secure airspace for airport and runway approach protection and for noise compatibility programs. An avigation easement is a conveyance of airspace over another property for use by the airport. The owner of an easement-encumbered property (servient property) has restricted the use of their property subject to the airport sponsor’s easement (dominant property) for overflight and other applicable restrictions on the use and development of the servient parcel.

Easement rights acquired typically include the right-of-flight of aircraft; the right to cause noise, dust, etc.; the right to remove all objects protruding into the airspace together with the right to prohibit future obstructions or interference in the airspace; and the right of ingress/egress on the land to exercise the rights acquired. The avigation easement on the property shall “run with the land” and any future owner’s use of the servient parcel is also restricted as described in the avigation easement.

The avigation easement provides the airport an indemnity from any future actions from the property owner from airport impacts and transfers to the new owner if the property is sold.