In order to provide an overview of the chosen topic for the Thesis, I will say that the main focus is the Analysis of human factors within the profession of the ATCO and furthermore how these factors are affected by the modernization of the industry. On a broader scale the thesis will deal with questions such as, how the human factors affect the tasks carried out by the controllers, the training they need to receive, the selection process every controller has to get through even before receiving this training, and the abilities an ATCO needs in order to be successful in all these different stages of selection, training and working placement. All these factors are what make the ATCO profession one of the more demanding careers and a difficult one to succeed in. Along with the study of human factors, I will be looking at how the changes and new developments in airspace capacity and technologies affect the way this job is carried out and the role played by the different human factors to support and facilitate these changes that are taking place. Nowadays, there is an unstoppable growth in the air industry. With the new open sky laws, and the continuous start up of new low cost airlines, the way airspace is currently and has been managed for the last decades will no longer work. Now, a whole new method is required to increase the capacity of airspace. Technology is fundamental in this industry. Controllers cannot see the aircraft under their control during most of the flight, only as the aeroplanes approach the airports, so they must rely on information given by radars and radio communication with the aircraft or with other controllers. Therefore, ATCOs need to rely heavily on the technology, although they can never be replaced by technology, or at least in the past and up to the current day the human component has been considered vital in Air Traffic Management (ATM).