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KptMarchewa • yesterday at 2:16 PM • 3 replies • view on HN

Redundancy matters when it protects from plausible issues.

> Hospitals don't stop carrying backup power supply for life-saving equipment just because "the power grid downtime has improved."

When power goes down, there is an immediate harm to patients. The grid downtime would need to be really implausible. Also, batteries would probably be okay now.

When fire happens - which is rarer now - it also rarer blocks the exit in a way that causes harm now.

Good example is ETOPS - https://en.wikipedia.org/wiki/ETOPS - some time ago, we required flights over ocean to have three or four engines. Now, reliability improved a lot, and the engines got good enough that single-engine operation is not so catastrophic as before.


Replies

bluGill • yesterday at 3:16 PM

Hospitals have all critical equipment on battery backup. The non-critical but important stuff can turn off for a minute while the backup generator starts.

Power outages tend to correlate strongly with situations where the hospital is most needed - bad weather injures a lot of people and takes the power out

CGMthrowaway • yesterday at 10:42 PM

>Good example is ETOPS - https://en.wikipedia.org/wiki/ETOPS - some time ago, we required flights over ocean to have three or four engines. Now, reliability improved a lot, and the engines got good enough that single-engine operation is not so catastrophic as before.

And yet, single-engine jets are prohibited from operating under Part 121 and must use Part 135 (the analogy here might be to an apartment building where the developer takes on the responsibility of structural code-compliance and safety, vs. a single-family home where the homeowner does).

There's a big difference in going from 4 to 2 engines, vs going from 2 to 1. And to be certified single engine jets must have battery backups, rapid depressurization tech, and a host of other things twin engines don't have to. In one case (Vision Jet) they use a whole-plane parachute to compensate for the lack of a backup powerplant

lokar • yesterday at 3:44 PM

Almost all apartment fires start inside an apartment. Improved standards for fireproofing between units, automatic doors, sprinklers etc means fires stay contained long enough for people to get out.