The European Facility for Airborne Research (EUFAR I3) is the European network of aircraft operators for research into the environmental and geo-sciences. Most of its members have expressed their support for the development of a European medium-altitude, heavy-payload and long-endurance research aircraft to conduct global scale multidisciplinary research projects in the troposphere. To pave the way for this unique European airborne research platform, the EU-funded COPAL project conducted a preparatory phase study. The project identified the best mechanisms to move from a national to a pan-European approach in the development of airborne research infrastructures. It also studied ways to operate the aircraft at the most efficient level by attracting a much broader community of users. In addition, it examined a European legal infrastructure to manage such a facility. One vital component of COPAL's activities was to draw up the specifications for, and estimate the costs of, the construction and modification of the research aircraft. Given the unique nature of this prospective airborne laboratory, COPAL canvassed instrument operators, small and medium-sized enterprises (SMEs) and labs. It also gauged the interest and nature of the instrumentation that could be hosted onboard. In view of the proposed aircraft's pan-European nature, COPAL developed a unique governance structure for evaluation of research projects and allocation of access. It also explored the platform's special logistical and operational requirements. COPAL concluded that the proposed aircraft is entirely feasible technically (7 such aircraft already exist in the US) and that the main bottleneck is a lack of commitment to investment at the national level. To help rectify this situation, nine partners have committed to building the necessary groundswell of national support. Because of the national fragmentation of research infrastructure support, the European fleet comprises numerous small and medium but no heavy payload aircraft. A common, pan-European initiative will allow countries that have not yet invested in airborne facilities to jointly develop a unique platform instead of increasing the duplication of small research aircraft. The Open Access scheme implemented by EUFAR will also allow the COPAL stakeholders to gain access to the whole European fleet, hence allowing researchers to select the facility the most suited to their objectives in term of performance and cost.