During the high-level conference on ‘Implementing the Single European Sky’ organised by the Hungarian Presidency on 3-4 March 2011, the Memorandum of Cooperation between Europe and the United States in the field of aviation research was signed. This memorandum is of special importance for the SESAR programme since it promotes interoperability between the European and US ATM modernisation programmes, SESAR and NextGen. Approximately 300 participants including international partners attended the conference. Patrick Ky, Executive Director of the SESAR Joint Undertaking, confirmed during a panel discussion that validation is a key element for enabling the SESAR deployment. He clearly identified the programme’s approach of validation in an operational environment by the members and partners including airspace users as the main strength of the SESAR programme. Mr Ky further outlined SESAR’s vision how to reach global interoperability with a view to the gate-to-gate concept, which in SESAR also includes airport operations.