MONITOR is a pilot study – funded in the EC research 7th framework programme and accomplished in cooperation of DLR (D), NLR (NL), the International Institute of Supplied Systems Analysis (IIASA, AT), Slot Consulting (HU) and the University of St. Gallen (CH) - with the aim to establish a permanent monitoring system of key factors and characteristics relevant for the development in air transport and of strategic importance for a wide variety of stakeholders, regulators, and scientists. Main objectives of MONITOR are - based on a holistic approach for the collection, analysis, updating and effective dissemination of relevant information - to generate a valid, harmonised one-stop solution of data needs for long-term air transport development related activities, especially for strategic decision making, modelling activities and quantification exercises such as ACARE Flightpath 2050, EUROCONTROL Long Term Forecast, the JTI Clean Sky Technology Evaluator and especially focusing on supporting the elaboration of scenarios. The results of the MONITOR project are available at www.airtransport-monitor.eu