The aeronautical industry has been introducing the computer technology, with an increasing pace, to accomplish different functions, with high levels of complexity, both in ground-based support activities and in embedded aircraft systems. This technological innovation brings not only improvements but also new and challenging problems, such as the case of digital equipment performance and behavior assessment and its influence on flight safety.In the case of embedded technology, a whole knowledge of its properties is necessary, due to its critical-safety characteristics. As for software, especially in embedded use, the required understanding about its operational behavior may be a hard task to accomplish. That is because there is still no general accepted quantitative technique for the software performance assessment.This paper surveys the informatics use evolution in aeronautical industry, the characteristics of embedded software, and the related concerns about this kind of application. It follows a discussion about reliability in aeronautical systems and procedures for software safety analysis. Finally it presents some methodologies for this type of analysis, regarding quality improvements and better confidence in embedded software operations.