Traditional flight computers -- including mechanical "whiz-wheels" (e.g. E6B, CRP series) and electronic flight calculators (e.g. ASA CX-3, Sportys E6-B) -- have long played a central role in flight planning and training within general aviation (GA). While these tools remain pedagogically valuable, their fixed form factors, constrained interaction models, and limited extensibility are increasingly misaligned with the expectations and workflows of pilots operating in modern digital environments. This paper presents E6BJA (Jamie's Flight Computer), a fully featured, multi-platform, software-based flight computer designed natively for Apple iOS, Android, and Microsoft Windows devices, with a complementary web-based implementation. E6BJA reproduces the core calculations of traditional flight computers while extending them through enhanced modelling capabilities and more accurate atmospheric (i.e. ISA-based) and performance calculations, including carburettor icing risk estimation and aircraft-specific weight and balance modelling for common GA aircraft. Each calculator is accompanied by embedded educational monographs explaining underlying assumptions, variables, and equations. We compare E6BJA with mechanical and electronic flight computers across functional, cognitive, and technical dimensions, demonstrating improvements in accuracy, error reduction, discoverability, and educational value. We also discuss design trade-offs associated with native multi-platform development and examine how contemporary mobile computing environments can support safer and more intuitive pre-flight planning. By combining the conceptual rigour of traditional flight planning with modern human-computer interaction design, E6BJA represents a meaningful evolution in pilot-facing flight tools, supporting both computation and instruction in aviation training contexts.