Aeronautical firms such as ATR (Avion de Transport Regional) have to benefit from strong brand image as an aircraft represents an implicate decision process. Thus, ATR was asking itself how improving its brand image. So, the research project aims to make ATR brand image more effective by making ATR employees fulfilling the brand promise. Through a complete review of the literature, the researcher gained the necessary knowledge to go through the internal branding subject area. It allowed her to define corporate brand, organisational culture, or behaviour control, which are some key concepts linked to the research purpose. To answer research objectives and hypotheses, quantitative method has been set up by administering questionnaire to all ATR employees over the world. The second method of data collection was semi-structured interviews and precisely focus group with five participants from different departments, with different hierarchical position and work experience at ATR. The questionnaire as well as the focus group were developed according themes identified in the literature review - company and product values, work organisation and management and internal communication - in order to get the feeling of employees. The results have shown the pride and global satisfaction of ATR employees in belonging to ATR. The corporate values are consistent with the staff's vision about their company and are well integrated. But, they also highlighted a lack of training and rewarding and possible improvements in internal communication content and support even if employees seems to be aware of mains communications messages. Moreover, results underline sharing and exchanges within team despite the absence of relationship with others services and superiors. Furthermore, employees would appreciate more information from their managers. To conclude the researcher advised ATR to set up an internal branding strategy in order to make their employees fulfilling the brand promise, and so, their brand image more effective, by working on Human resources, internal communication and brand management strategies. Futures researches should focus on internal branding strategy in intercultural environment but should also analyse employees' feelings and answer regarding their hierarchical level and geographical situation.