barit1 said
The obvious answer is a dual-fueled engine - a few minutes' supply of hydrogen (or methane) under pressure would at least allow you to pick a better crash site.
It would have to be a fuel storable as a liquid to get the package down to a reasonable size - maybe propane - and it would still require a large, heavy, high pressure bottle. Why does that remind me of the Qantas B744 depressurisation??
Maybe a simpler alternative would be to provide a second fuel feed pipe from tank to engine. At present, the engine's ability to "suck" fuel only protects against a boost pump failure - a dedicated pipe would protect against ANY fault in the normal supply system.