Airworthiness Certification is a globally accepted process to attest civil aircraft safety over the compliance with a set of requirements (certification basis) that aims to avoid the occurrence of aeronautical accidents due to design issues. Considering military airworthiness, in a similar way, the mission accomplishment verification process, in a product development contracted by the Brazilian Air Force (FAB),should seek to meet the needs and capacities to be acquired by FAB to support operational units. Therefore, clear mission requirements are key points for a good contract execution. This study has made use of a robust hazard analysis technique (STPA -System-Theoretic Accident Model and Processes) in order to investigate the causal factors which leads to negative impacts on the contract elaboration process for aeronautical military products in Brazil. STPA uses System Theory to model any process as a feedback-control structure. Focusing on losses we want to avoid, the method considers the hazards, safety constraints, unsafe control actions, causal factors and based on that, proposes requirements(which can be understood as recommendations),showing a path throughout the earlier phases of Brazilian military products life cycle to improve the contract elaboration process.