2023-14927

Document Headings Document headings vary by document type but may contain the following: • the agency or agencies that issued and signed a document • the number of the CFR title and the number of each part the document amends, proposes to amend, or is directly related to • the agency docket number / agency internal file number • the RIN which identifies each regulatory action listed in the Unified Agenda of Federal Regulatory and Deregulatory Actions See the Document Drafting Handbook for more details. Department of Transportation Federal Aviation Administration • 14 CFR Part 21 • [Docket No. FAA-2023-0938] AGENCY: Federal Aviation Administration, DOT ACTION: Notice of availability; final policy and disposition of comments. SUMMARY: The Federal Aviation Administration (FAA) announces Policy Statement PS-AIR-600-39-01 for demonstrating an aircraft is a “radio altimeter tolerant airplane” or a “radio altimeter tolerant rotorcraft” using a method approved by the FAA. DATES: This policy is effective July 19, 2023. FOR FURTHER INFORMATION CONTACT: For technical questions concerning this policy statement, contact Barbara Clark, Supervisory Aviation Safety Specialist, Avionics Navigation & Flight Deck Unit (AIR-626B), 800 Independence Ave. SW, Washington, DC 20591; telephone: 202-267-8569; email: barbara.clark@faa.gov. SUPPLEMENTARY INFORMATION: Background The current performance standards for radio altimeters (also known as radar altimeters) are based on the presumption that no occupancy of an adjacent radio frequency spectrum would cause interference with radio altimeters. During 2021, the radio frequency (RF) operating environment surrounding radio altimeters substantially changed when wireless telecommunication service providers began offering 5G C-Band services near the 4.2-4.4 GHz band. In both the U.S. and internationally, this band is allocated on a primary basis for aeronautical radionavigation service, which is used by aviation radio altimeters. The FAA subsequently determined that radio altimeters could not be relied upon to perform their intended function if they experience interference from 5G wireless broadband operations in the C-Band. Deployment of the new 5G C-Band services prompted the FAA to address the risks posed by RF interference to radio altimeters. On December 7, 2021, the FAA issued airworthiness directive (AD) 2021-23-12 [1] for transport and commuter category airplanes equipped with a radio altimeter and AD 2021-23-13 [2] for helicopters equipped with a radio altimeter. AD 2021-23-12 and AD 2021-23-13 prohibit certain flight operations requiring radio altimeter data when flying in the presence of 5G C-Band interference as identified by Notices to Air Missions (NOTAMs). In response to AD 2021-23-12, the aviation industry developed a method to show compatibility with 5G emissions in the United States national airspace system for the initial 5G deployment, which was limited to 3.7-3.8 GHz, and the 5G spurious emissions in the radio altimeter band (4.2-4.4 GHz). The FAA accepted this method as support for proposals for alternative methods of compliance (AMOCs) with AD 2021-23-12 and AD 2021-23-13. These AMOCs used standardized assessment parameters, values, and methods to estimate an installed altimeter system protection radii or distance. Aircraft with an altimeter operating beyond this distance from all 5G base stations would not expect harmful effects from RF incompatibility and indeed could depend upon the radio altimeter system to perform fully its intended function. These AMOCs were based on interference thresholds of specific individual radio altimeter transceivers. That is, each transceiver was tested to benchmark their performance in the presence of out-of-band and in-band C-Band signals.[3] The thresholds were then modified and tailored to installation factors specific to the installed platform ( …

Fonte: Federal Register (federalregister.gov). Texto original em inglês. Conteúdo sanitizado por segurança.