At the end of November 2017, the FAA put into place changes to reduce the amount of noise at the Phoenix Sky Harbor International Airport and surrounding area. The initiative responds to a ruling from the U.S. Court of Appeals for the D.C. Circuit that called to cancel the satellite-based procedures implemented in September 2014. Although the procedures aimed to decrease airport delays, the City and neighborhood groups said increased noise was the main result of the changes.
In an attempt to better understand noise standards, we have dissected noise stages, noise levels, and some things to avoid in order to comply with these noise standards.
Levels & Stages
Each civil aircraft must meet certain noise certification standards through the FAA. The standards lay out the maximum noise level change requirements by “stage” designation. Any aircraft that is certified for airworthiness must also comply with noise standard requirements to receive a noise certification. According to the FAA, the certificates are issued in order to ensure “the latest available safe and airworthy noise reduction technology is incorporated into aircraft design and enables the noise reductions offered by those technologies to be reflected in reductions of noise experienced by communities.” The FAA follows the International Civil Aviation Organization (ICAO) Annex 16, Volume 1, Chapter 4 standards for noise stages and certifications. Stage 5 certificates are being implemented, meaning even stricter regulations when applying for certificates due to advances in technology. Now, aircraft with a Minimum Takeoff Weight of 121,254 pounds (55,000 kg) or more applying for a certificate on or after December 31, 2017 must meet new restrictions. Stage 5 certificates will be issued for aircraft with a MTOW of less than 121,254 pounds (55,000 kg) on or after December 31, 2020.
Change in weight solution
With these stringent restrictions put in place, here is how to handle an acoustical change when adding to the weight of the airplane without also having any other changes made to the engine, propeller, etc. There are many ways to calculate whether or not there is a large acoustical change when adding extra weight to the plane. Check AC 36-4 (most current version to date linked at bottom of blog) to learn more. Once a change has been determined or calculated, it is important to develop new noise levels for the modified airplane, which could mean a full part 36 Appendix G noise test be conducted. Additional adjustments may be made (within reason) to create new noise levels. Note: Noise levels found in the AFM cannot be adjusted.
With a better understanding of noise restrictions and constant advances in technology, hopefully incidents like the Phoenix Sky Harbor International Airport are mitigated, creating harmony between communities and aviation departments alike.