Half of aviation safety (especially for commercial aviation) is done on the ground and has nothing to do with aerospace engineering. Stuff like shift times for pilots and ATC, mandated rest periods, proper ground equipment in zero visibility conditions etc. Many developing countries cut corners on maintenance and spare parts. Mandated use of safety technologies (the DC helicopter incident was entirely preventable). Airports that are designed with safety in mind. If you have a dual engine failure immediately after take-off on an airliner in the middle of a built-up city you are generally fucked. Midwestern airports are the best if you have to do a forced approach. Transport category aircraft (basically anything bigger than a 12 seater plane) don't really have many options, they can't easily land on the runway like smaller planes. That's why the Hudson was a miracle. Your airliners stay safe through constant maintenance and inspections. Dual engine failures are very rare (unless through deliberate pilot action like the recent case in India).

On the engineering side you can look up ETOPS and the various ICAO and FAA and EASA standards for airliner class aerospace engineering https://en.wikipedia.org/wiki/ETOPS

Trust me, y'all think airplanes are "safe" because of some sort of magical protocol. No single protocol actually works. It's mostly lots of layers that are stacked on top of each. It's why in aviation, catastrophic failure modeling uses something called the Swiss Cheese model; you need every single hole (error or failure) to line up to generally trigger a complete breakdown in safety. It may sound counter intuitive, but by aviation safety philosophy, a canvas and wooden frame plane operated under commercial standards and kept to a strict inspection schedule is "safer" than e.g. a privately operated 737 that doesn't follow manufacturer maintenance standards.

NASA has plenty of guidelines for writing "safe" aviation software. I doubt any software engineer will be willing to entertain the level of effort and certification needed to comply with those for e.g. their Django side project.