A good example of a recent technical failure where one likely alternative is "everyone dies" https://en.wikipedia.org/wiki/British_Airways_Flight_38 https://en.

A good example of a recent technical failure where one likely alternative is "everyone dies" https://en.wikipedia.org/wiki/British_Airways_Flight_38 https://en.wikipedia.org/wiki/British_Airways_Flight_38 The engine needs to be able to run without electrical power, or you need to convince the FAA that your backup will fail with an extremely small probability. This is one of the reasons magnetos + carburetors are common in general aviation