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Comment by lp92 | Hacker News Reader

>The FAA cited an October 13 event where a fiber optic cable connecting Houston George Bush Intercontinental Airport to the FAA’s network was cut outside an airport gate, leading to the loss of data services between FAA facilities and requiring a ground stop.

Do they seriously not have a backup connection? I would have expected them to have a backup stelite or maybe even a 4G/5G mobile data system in place.

If I can use my phone as a Hotspot when Comcast is doing some service so I can work, I don't understand what idiot designed an airport without backup connections.

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> Do they seriously not have a backup connection?

That was the backup connection. The primary failed, and concurrently the backup had been severed by a construction crew.

If you don't regularly test your backup, you don't have a backup.

Useful aphorism in general, not terribly applicable in this case. Even if it had been tested regularly, it was cut around the same time the primary failed. Regular testing doesn't stop construction crews from cutting a line.

A more useful comment might have been to say something about the depth of the backup, having only one backup connection not being enough or something.

If you are curious: one of the most frequent problems that disables fire sprinklers is maintenance forgetting to turn the water back on. No one notices until it is too late.

No one notices the thousands of times the redundant links works just fine. We only notice when the primary has an outage and a construction crew cuts a fiber line at the same time.

If you’re relying on your redundant link thousands of times you probably need a third link.

> I don't understand what idiot designed an airport without backup connections.

I have literally spraypainted the pavement and wall - "One fibre goes here, and down on the corner there, the other fibre goes there" - just to ensure a good separation of routes. I want the pinch point to be within the rack that the routers sit in.

I don't get why an airport can't do similar.

That airport did have two redundant connections, this was a swiss cheese failure where one was under maintenance and the other was severed by an independent event.

> one was under maintenance

So they didnt have a redundant connection. They had 1 live one that was severed.

they did... it was just singly redundant. they would need double redundancy here. so 3 connections, not 2

Taking one connection out for maintenance and leaving only 1 live connection is not redundancy, it is a failed backup.

Redundancy is always having more than one live connection.

The primary was being inspected and the secondary failed, there were redundant systems.

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