Originally Posted by
rickair7777
The US UAM industry was originally shooting for a significantly lower standard than 10^ -9 standard. The european UAM industry however just committed up front to 10^ -9, not sure where the US folks stand now.
Also worth noting that 10^ -9 is the allowable chance of a serious accident per flight hour.
So it's system-cumulative, it does not mean every component needs that level of reliability, that can be mitigated with redundancy.
Multiple independent systems (ie parallel) can each have a lower reliability, with each backing the others up. This is why we have about six hydraulic pumps... hard to build a high temp, high rpm, high pressure pump with that kind of reliability.
But for remote piloting you'd need MULTIPLE comms system, and even then I'm not sure ANY known technology can achieve the needed reliability. How often do your HYD pumps "hiccup"? How often does your in-flight wifi hiccup?
Are you going to build six separate space and ground based systems? And you'd have to use different frequencies and protocols to mitigate hacking/jamming, can't just use six copies of the same system (like you can with hydraulic pumps). If it can be done technically, it most certainly cannot be done economically.
The way it will play out is anyone who seriously tries will soon be in the lobby of FAA HQ, hat in hand, looking for waivers and favors. Good luck with that:
https://www.reuters.com/article/us-b...-idUSKBN20J2M3
The technology required for this level of redundancy is more expensive than having 2 pilots.
This is the big hurdle right now.
At the same time, just like you say, the redundancy is cumulative. But when it comes to technology, you can not duplicate the same tech and assume the redundancy is doubled because the systems would not be independent then.
You'd need probably 6-9 systems, all independent of each other, with not a single common line of code. NASA used to have different companies program the redundant systems, so they would not have bugs that were common with each other. This is simply impossible to do with any sort of financial return.