All flights in the United States are grounded until further notice,

[Brad Sallows]

As I wrote earlier the disadvantage to centralization. One group of cables in a remote location and it took down the entire system. I would assign some of the blame to the people who originally designed it without building in the ability to change equipment and wiring harnesses out and verify acceptance in total isolation.

How do you know they didn't design it that way and that the people doing the upgrade didn't 100% understand what they were upgrading?