[DigitalJack]

That’s what sensor fusion is for.

That said, inertial nav can take a plane across the country without correction and get within sight of the target.

I think integrating actual speed while on rails would be vastly more accurate.

And really, it just need to augment gps.

[sobellian]

Sure, sensor fusion sounds reasonable. My mistake, I thought you were referring to GPS and speed integration as separate options.

[AstralStorm]

Are you trying to reinvent already outdated ETCS level 2?

[DigitalJack]

I'm not inventing anything.

And why would it be outdated if it works, and we (US) aren't using it.