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Comment by WJW | Hacker News Reader

Interesting! Do you know if it can just survive it and then needs to be scrapped or is it possible to replace the damaged hull plate(s) and (after thorough inspection) put the plane back into service?

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They certainly can repair it, but in this case, given that Delta is already in the process of retiring the Boeing 717 (and replacing it with Airbus 220), they might just decide that it's not economical to do it anymore...

The specific plane (1), N955AT, is 22.6 years old. So not young, but not completely geriatric either. Delta seems to be the only major operator of the plane type, so don't think there'd be too many buyers. Delta also seems to have a fair few in storage(2) so a fair guess would be that they'd scrap it but keep the parts that they could still use on other planes as spares.

1) https://www.airfleets.net/ficheapp/plane-b717-55017.htm 2) https://www.airfleets.net/listing/b717-1-statdesc.htm

Delta and Hawaiian are the two US operators. Hawaiian loves it, and is struggling to replace it. They use them for island-hopping. Modern airliners don't do well in this use case — modern engines have been engineered to tight tolerances to extract fuel economy, and their thermal designs rely on the cold air at cruise altitude to keep them healthy. Island hops are too short and too low for that to hold. The engines on the 717 handle it just fine, but anything else on the market will require the planes to sit on the tarmac for a significant length of time between landing and takeoff for them to cool enough, and would destroy Hawaiian's current network design, which has lots of quick flights and tight turns.

Delta announced retirement a long time ago, but has been not-so-secretly buying up as many as they can get, mostly as spares for parts to keep the fleet going because it's so useful for them. Also, the A220, its replacement, has a single engine, the Pratt & Whitney Geared Turbofan, which has had an incredibly rough entry into service — everyone was concerned that the gearbox would be an issue, but it has been mostly rock-solid, and it's the engine core that's had dozens of issues. An airline in India has over half of its fleet grounded and filed for bankruptcy last month because P&W can't repair their engines.

The Hawaiian Islands are sort of an interesting case. Island hopping is short for jets (and a lot of people don't really like flying small props). But they're really too far apart for a ferry service between the major islands; it was tried at one point but went out of business.

I think the aversion to props is a North American thing in particular. Which doesn't help Hawaiian but for Europeans it's completely normal for small hops to be in a mid-size turbo-prop (these are still jet engines, they're just spinning a propeller instead of shoving hot gas out of the back to go faster) aircraft. Sure, it's not necessarily as comfortable as an A380, but you're not stuck there for hours.

>I think the aversion to props is a North American thing in particular.

That may be. I actually flew a prop from Maui to Big Island last time I was in Hawaii. But when I was growing up they used to be super-common even on East Coast "commuter" flights especially from smaller airports.

The Hawaii Superferry went bankrupt mostly due to political and environmental protests. Distance between the main populated islands isn't very far.

> The engines on the 717 handle it just fine, but anything else on the market will require the planes to sit on the tarmac for a significant length of time between landing and takeoff for them to cool enough

Is it just a matter of the brakes and tires/wheels needing to cool down or other parts need the cooldown period as well?

No, it's entirely the engines — there are a lot of moving pieces of metal that have to safely expand and contract in understood cycles. The brakes and wheels are fine with tight turns (assuming you don't have to use max braking). Southwest operates on a very similar timetable, and in fact flies a few of the more-trafficked Hawaii island hops. The difference is that Hawaiian's 717s _only_ fly island hops all day, every day. Southwest rotates its planes, so any given plane will do at max two island hops before it flies the 6 hours back to mainland and gets plenty of cooling time, e.g., LAX -> Honolulu -> Hilo -> Honolulu -> LAX.

Airplanes rarely get scrapped for parts because of incidents like this. They have pretty extensive maintenance and repair checklists, but afaik the rate of making vessels like this airworthy is pretty high.

It really is amazing how resilient planes are, I'm pretty hooked on this YouTube series in which a guy gets given a plane that's been sitting in the open for 15 years or so on the condition he can make the thing run again. https://www.youtube.com/playlist?list=PL5IMg7-HLL1Y4K06HdsDB...

> Airplanes rarely get scrapped for parts because of incidents like this. They have pretty extensive maintenance and repair checklists, ...

And yet these "extensive maintenance checklists" did not prevent such a serious malfunction. They were lucky that the weather was cooperating. In bad weather and strong winds who knows what would have happened.

Tell me you don't know what you're talking about without telling me you don't know what you're talking about.

These are machines. Machines break, no matter what the maintenance regime is. The number of cycles on these planes is awe inspiring, and while there are always squawks, the captain and FO always have the authority to ground a plane for any maintenance items they don't like.

> They were lucky that the weather was cooperating. In bad weather and strong winds who knows what would have happened.

Exactly the same thing would have happened. Maybe if it was raining or very cold we wouldn't have quite as much passenger cell phone footage from the runway. But weather had nothing to do with this, nice weather didn't make the landing any easier, and bad weather wouldn't have made it any harder. Ridiculous.

Weather had nothing to do with it. They had a warning light come on during landing that the nose gear had a safety issue, so they did another few passes, requested emergency services available at touchdown, and then did effectively a pretty normal landing (just holding the nose up a little longer than normal).

Nobody is assuming "extensive maintenance checklists" are _preventing_ serious malfunction. They do however reduce the risk for such events to occur to an acceptable level.

The likelihood for a malfunction is never zero.

Wearing a seatbelt doesn't prevent you from dying in a car accident, guess we might as well stop that too, sounds useless to me.

They can most certainly repair the plane. If you've never heard of the "Gimli Glider", check this out...

https://en.wikipedia.org/wiki/Gimli_Glider

That's an insane story. As much as I hate flying, modern aviation infrastructure is one of mankind's most impressive feats.

They can fix and fly this almost certainly.

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