Noise assessment of taxibotted versus conventional taxiing operations using a phased microphone array

In sustainable aviation important aspects are to reduce the greenhouse gas emissions during flight, which have a worldwide impact, and to reduce the noise during take-off and landing. However, in addition airports have an increasing interest in reducing emissions during ground operations to improve the local air quality and potential noise issues. In 2020, Amsterdam Airport Schiphol started a pilot for sustainable taxiing with a pilot-controlled hybrid-electric aircraft-towing vehicle called TaxiBot. During the operational testing, a noise level assessment was performed to evaluate the noise levels to which ground workers are exposed.
For the noise measurements a phased microphone array was used. This allowed for noise source identification through beamforming. In addition, the microphones are used for a noise directionality assessment. Both methods are used to compare the noise sources and levels of a taxibotted versus a conventional taxiing operation. The results show that a taxibotted pass-by produces 7.1 dBA less at a 90deg emission angle at the source position and thus significantly impacts the noise levels on the airport. The directionality assessment shows that the taxibotted operation is especially silent while approaching the observer.