If they don't know what time it is, how can it be 4.8 us off?

> All of the atomic clocks continued ticking through the power outage last week thanks to their battery backup systems, according to NIST supervisory research physicist Jeff Sherman. What failed was the connection between some of the clocks and NIST's measurement and distribution systems, he said.

But what was the SLA?

For reference, that's 4720 light feet or 1440 light metres.

If the official time drifts by 4.8 microseconds, should I worry about my VHS timer recordings?

> and a backup generator subsequently failed,

I wonder what the failure was. I also wonder if they load tested the unit(s) to ensure full operation at some recent point. That's how you find weird things like fuel fouling that obstructs pipes and filters which under no-load testing scenarios would not be an issue but could potentially stall under load.