Standards Development

Scope

This international standard addresses the quantification of the noise impact of multirotor UAS with maximum take-off mass (MTOM) less than 150 kg. The standard can promote understanding of the noise characteristic of the UAS and provide reference for both manufacturers and regulation bodies. The scope of this standard includes:

1. This standard specifies noise metrics, test conditions, testing procedures, data processing and requirements of the test facility/area, test configuration, test points and instruments to quantify the noise of UAS with MTOM less than 150 kg under different working conditions including hovering, taking off, descent and cruise.

2. The tests can be conducted either in an anechoic chamber or under outdoor conditions according to the size/weight of the UAS.

For the anechoic chamber tests, the standard specifies and the size, cut-off frequency and the impact of the flow recirculation.

For the outdoor tests, the standard specifies the procedures to minimize the impact of metrological effects, the atmospheric corrections, wind speed correction and flight path measurements. Excluded:

UAS with MTOM larger than 150 kg (the noise characterises and the impact on environment are different)

Purpose

Within the previous decade, multirotor UAS have greatly impacted the global market with unique and cost-effective vehicle systems for photography, industrial surveying, logistics, modern agricultural, civil engineering inspection, etc. An UAS can exert a significant impact on the living environments of humans and wild lives during its operation at low altitude in both high population density urban and rural areas. The adverse environmental impacts include UAS noise, which increases significantly with weight.

However, standards to quantify the noise impact are not established so far. The characteristics of UAS noise vary in different operation conditions. The modern agricultural UAS is designed to operate at a few meters above the ground level. the logistic UAS is operated mainly in cruise condition. The UAS for civil engineering inspection may operate in areas surrounded by large acoustically reflecting structures. The flight conditions of UAS are different with large civil transport aircraft, and the noise characteristics are therefore perceived differently, making the existing noise test codes such as ICAO Annex 16 for large aircraft, helicopter and tilt-rotor vehicles unsuitable partially. These tests codes were development for vehicles that typically operate far above civilians and urban structures, which are remotely relate to the vehicle design and configuration of multirotor UAS.

The recently published European Commission Delegated Regulation (EU) 2019/945 for UAS details a noise test code following EN ISO 3744:2010 standards. The test code considers the three-dimensional noise radiation characteristics of multirotor UAS by measuring the sound power level from indoor and outdoor test environments. However, the measurement metrics is limited only to the flight attitude of hovering. There was no guideline in considering flow recirculation or extracting the noise spectral characteristics that significantly impact human noise perception. In addition, the document considers UAS with MOTM up 25 kg. There is a need to standardize the noise test practices for heavier UAS up to 150 kg, which is becoming more common for mapping, agriculture and logistics, and will have a greater impact on the general community.

The following benefits are expected by a standardized noise measurement test code for UAS with a MTOM less than150 kg: 

1. The proposed noise test code will standardize the evaluation process of UAS for indoor and outdoor testing. The standard will provide standards in performing noise measurements at the typical UAS flight-phases, take-off, hover, landing and cruise.

2. For the UAS manufacturer, a standardized noise evaluation test code will help ensure their technological developments with a guidance of a robust test process. This will provide a foundation on which manufactures can innovate and develop quieter and more advanced systems.

3. For the public, a standardized noise evaluation test code will help communicate the impacts of new drone technologies to the general community, where UAS operators may wish to flight (i.e., wildlife surveying, civil engineering inspection, photography). This standard would help reduce environmental impact and enhance the local quality of life.

4. For the regulators, the proposed noise evaluation test code will provide a means to propose noise regulation and noise reduction targets, specifically for drones.

Consider the following: Is there a verified market need for the proposal? What problem does this standard solve? What value will the document bring to end-users? See Annex C of the ISO/IEC Directives part 1 for more information. See the following guidance on justification statements on ISO Connect:

https://connect.iso.org/pages/viewpage.action?pageId=27590861 S