The present research sits within a broader study developed under a Ph.D. Programme in Psychology at Faculty of Psychology in Lisbon University (Faculdade de Psicologia da Universidade de Lisboa) and EASA (European Union Aviation SafetyAviation safety Agency). As AI-based systems are entering into the sector, it was important to listen to aviation professionals, assessing their level of acceptance of AI, applied to eight different hypothetical aviation scenarios. More than that, taking into consideration the ones that expressed their opinion as not acceptable (171 professionals), it was important to unveil the motives behind this negative opinion (2395 contents). Conclusions showed that aviation professionals have ethical concerns about the AI-based system itself (30%), about the consequent human negative impact when using such systems (28%), about how their data is used by the technology (11%), and about AI-based systems putting aviation safetyAviation safety at risk (6%). Results show a detailed motive basis for non-acceptance of AI, to which aviation organisations, research centres, and aviation professionals are invited to do further research, to ensure that AI-based systems applied to aviation besides being mandatory safe can also be ethically based.