With a first project that ran from 2005 to 2007, common core profiles for both Aircraft Mechanics and Aircraft Electrician have been developed between the four Airbus “countries”: France, Germany, Britain and Spain. These core profiles are based on the definition of so-called Typical Professional Tasks (TPT) of which particular lists have been validated as to be in common to the four sites under study. The TPT emerged out of an analysis of the work activity of expert workers in both trades. The purpose of the proposed presentation will be to elaborate on the further division of these quite general TPT in sub-tasks and further more in elementary tasks, directly corresponding to the results expected from the worker. Such an analysis faces the difficulty to find the right “size” for those elementary tasks, avoiding the atomization of the action. On this level of desegregation of the workers’ actions training programmes often are developed. With this theoretical approach the initiative of designing European Credit Units for VET (ECVET) should be discussed for both its technical but mainly its theoretical feasibility.