In the civil aviation certification the software has an unlike treatment due to its peculiarities and also for being a relatively new item. There is no specific software certification requirement in the FAR¹ – FAR 33.28 is the only section that mentions the word software. The FAA² recognizes the considerations presented in RTCA/DO-178B³ as an acceptable means for approval of software used in airborne systems for civil aviation. The CTA/IFI/CAvC⁴, responsible for the type certification in Brazil, has been applying RTCA/DO-178B since it was issued. The purpose of this paper is to present the experience of CTA in applying DO-178B, focusing on those technical issues that were source of controversy among certification authorities and industries. This paper is relevant at present time as RTCA and EUROCAE⁵ have recently organized a Special Committee⁶ intending to issue DO-178C by the end of 2008.