The RANNTAC programme, together with the RESOUND programme on engine noise source reduction technology and the RAIN programme on the reduction of airframe and installation noise are the three main and complementary pieces of the proposed R&D effort co-ordinated at European level by the X-NOISE thematic network on external noise. The objective of the combined programme is to deliver within 8 years, aircraft environmental noise abatement of 6 dB both at departure from airports and at arrival relative to current technology demonstrated by aeroplane industry. The objective of RANNTAC is to acquire the technology necessary to support the development and manufacturing of turbofan engine nacelles featuring noise reduction devices and designs enabling to achieve up to 4 dB attenuation on engine internal noise sources in addition to that achieved by currently produced acoustic liners. Half this noise reduction will be demonstrated at the end of the programme while the means to achieve the remainder will be identified and defined for further large-scale demonstration.