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Comment by fnordpiglet | Hacker News Reader

I’d note that commercial airplanes generally operate with 6-7 9’s of availability. For anyone that’s ever built a system with 5 9’s, this is impressive. In fact it’s impressive enough you probably don’t think twice about sleeping on a flight.

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Six 9s would be half a minute of downtime per year.

I don't see how that is possible given the maintenance required for these planes. Even the simple A checks ground a plane for hours every couple hundred flights while D checks take months to complete every 6-10 years.

Edit: minute not hour

> I don't see how that is possible given the maintenance required for these planes

You normally only count unplanned downtime in those stats for aircraft.

By my math, six 9's is 30 seconds, not 30 minutes?

(1 - 0.999999) * (60 * 24 * 365)

EDIT: This chart agrees: https://en.wikipedia.org/wiki/High_availability#Percentage_c...

You are correct. Forgot what my units were in bc.

The six 9s are probably meant as catastrophic failure rate, not downtime.

It counts any event where the plane has an unplanned event including unscheduled maintenance, unplanned flight deviations, and of course catastrophic failures.

If something goes wrong, does it matter whether you are asleep or awake?

Only when a flight attendant is asking on the intercom: "We don't mean to alarm anyone, but is anyone on board a pilot?" and you happen to be one.

I know a commercial pilot who used that as a joke once and got in trouble. The plane in question had several pilots on it but the rest of the passengers didn’t find it funny for obvious reasons.

It's entirely a different kind of flying

All together

It's entirely a different kind of flying!

It's entirely a different kind of flying

“We don’t wish to cause any alarm, but is there any one on board who is familiar with regular expressions, cron expressions and parameter expansion rules in bash?”

Several overweight men stand up and walk towards the cabin, immediately throwing off the weight distribution and the plane plummets.

You joke but… There was an emergency nose high recovery out of San Diego airport where at one point the pilot had every passenger crowd into the first class cabin…

The flight was saved.

It looks like that was https://en.wikipedia.org/wiki/Delta_Air_Lines_Flight_1080

You mean.. for free?

I hope the first class passengers were well compensated for their traumatic experience.

Hopefully you didn't have the fish.

Looks like I picked the wrong week to quit amphetamines

Looks like I picked the wrong week to stop sniffing glue!

woosh!

That is presumably historic data though?

6-7 nines is a lot of nines and we’ve had a couple of issues in quick succession now

> it’s impressive enough you probably don’t think twice about sleeping on a flight.

I don't think twice about sleeping on a flight because I've already made my bed at that point - nothing I can do if something goes wrong.

(Well, I've woken my wife when a doctor was called for before, but that's about the extent of my usefulness.)

I’ll wager if you got into a situation you can’t escape where you had a 30% chance of a horrific death over the next six hours you wouldn’t snuggle into your sound suppressing headphones and doze off between snacks no matter how inevitable things are.

Where in the world did you get that 30% number? Even on Boeing's worst planes, the chances of any incident are still much more like 0.003% or something like that. "30%" is just fearmongering.

Meh, had worse odds and slept fine. Notably, however, odds are not nearly that bad, even in Aeroflot flights out of Africa. Or for that matter, combat flights in war zones.

Besides, a plane crash is far from the worst way to go. Dramatic, sure.

But dementia? Cancer? That’s often a pretty miserable death.

Plenty of things out there to get worried about if you want.

> I’d note that commercial airplanes generally operate with 6-7 9’s of availability.

Maybe they used to, but Boeing has been doing rather worse and that’s the point here isn’t it?

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