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Ask HN: What's Happening at Southwest?

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Re: Ask HN: What's Happening at Southwest?

#21

Post by greesil »

shagie wrote: post #12
_yb2s wrote: post #8

Earlier quoted context omitted.

I find it hard to believe that compute power is the limitation here… something like simulated annealing would probably provide a reasonable, even if far from optimal solution on a regular PC. I imagine the feeding all of the data and constraints in is a bigger issue, when there is a lot of confusion and disorganization.

It would, and that's likely what they're using - but it isn't perfect . When it becomes non-perfect and you get a number of events that throw it off (like storms causing certain legs from not getting completed to move the plane to the proper spot and holidays causing disproportionate load in certain parts of the network), then everything gets messy.

FTA: "In the event of a disruption you call scheduling and they manually adjust you"

Maybe the airline industry needs AlphaScheduler deep learning with monte carlo tree search. Or stimulated annealing. These cheap short sighted stuffed suits with MBAs who think that a fat tail refers to some part of the airplane.

Re: Ask HN: What's Happening at Southwest?

#23

Post by wwweston »

mattbrewsbytes wrote: post #7

Basically what I read was the former CEO was accountant educated and focused on stock price and financials and ignored system upgrades for like a decade. That coupled with their decentralized nature of operating (no hubs or star pattern) the recent storms caused their systems to not “know” where people or planes were even though the people knew where they were. That knowledge is the critical feature because hours of…

> Having personally experienced the delays and issues with SW earlier this year I can suggest not flying them other than direct flights

And it seems to me they've cut direct flights -- still plentiful on many of the hops (say, LAS LAX) but scarcer on longer routes (say SLC LAX).

And on the shorter routes, driving is roughly competitive time-wise...

Re: Ask HN: What's Happening at Southwest?

#24

Post by cjalmeida »

shagie wrote: post #3

A key point is how they do routing - https://www.ajot.com/news/southwest-air-faces-gridlock-with-... > Unlike competitors that use a so-called hub-and-spoke system to funnel passengers to large airports, Southwest is focused on point-to-point service, flying the same aircraft — Boeing Co. 737s — on trips that may hopscotch around the US. With a hub and spoke system, all the planes go from A to HUB and then from the H…

I’ve worked on airline scheduling system and solving to optionally is indeed NP-hard and scales badly.

However you can get to a very good spot with heuristics. This particular issue with SW looks like bad data collection(crew has to phone their location!) and a combination of lack of reserves, bad weather and holidays surge.

Re: Ask HN: What's Happening at Southwest?

#25

Post by rektide »

hrunt wrote: post #13
mtmail wrote: post #2

Via reddit/r/bestof https://old.reddit.com/r/flying/comments/zw5lsl/southwest_pi... "So the storm came and it impacted ground ops so bad that many many crews were now “unaccounted” for and the system in place couldn’t keep up. Then it happened for several more days. By Xmas evening the CS department had essentially reached the inability to do anything but simple, one off assignments. And to make matters worse, the ph…

> "I used to work for a large company trying to fill the void [huge gap in the market for good aviation scheduling software], and our software was damn good too. SW was one of the airlines interested, we would demo it exactly like the scenario today, but it was "too expensive" and they stayed on their homebuilt stuff." This is a common situation in any industry. A company has a solution it self-developed in its infan…

> and the replacement cost is a one-time, relatively high purchase fee (with, usually, a similar if not higher ongoing maintenance cost)

i'd wager complex scheudling software is probably licensed, not sold outright. many many millions a year to license.

but yeah, lot of good factors you cite.

Re: Ask HN: What's Happening at Southwest?

#26

Post by mattbrewsbytes »

ww520 wrote: post #9
mattbrewsbytes wrote: post #7

Basically what I read was the former CEO was accountant educated and focused on stock price and financials and ignored system upgrades for like a decade. That coupled with their decentralized nature of operating (no hubs or star pattern) the recent storms caused their systems to not “know” where people or planes were even though the people knew where they were. That knowledge is the critical feature because hours of…

Ah so bean counting treated IT as a cost center and cut CapEx to the bone. Running things with no reserved capacity, crew wise and system wise, is just asking for a catastrophic fall off the cliff style shutdown. Edit: a simple queue theory can explain why no reserved capacity leads to system breakdown.

Yup. For me they had brand prominence because of various customer friendly things like bags fly free, sit where you want, etc. It will take a mountain of good reports from other people over a significant period of time for me to want to fly with them.

Re: Ask HN: What's Happening at Southwest?

#27

Post by pavlov »

Simon_O_Rourke wrote: post #17
phil21 wrote: post #15

From what I know... Not affiliated at all with the airline industry, but I fly a lot and tend to nerd out on this stuff... Their crew (and flight) scheduling software functions in a manner where it more or less simulates a "perfect" day of operations. Airplanes take off on time, land, and continue on. If anything disrupts this simulation, crew members had to call in and talk to someone to update the computer system t…

In this age of more or less fully network connected devices, this kind of a setup seems archaic in the extreme, probably likely to be some hangover from the 70s or 80s.

Airline systems are some of the oldest computing architectures in use.

The Sabre reservation system was created by IBM for American Airlines in the 1950s — when a computer filled an entire building floor and was built out of vacuum tubes — and remains actively used today by multiple airlines. The programming language has been switched several times over the past 60+ years, but essential compatibility remains.

Re: Ask HN: What's Happening at Southwest?

#28

Post by lpapez »

rjh29 wrote: post #16
mikewarot wrote: post #4

How could a CEO let this persist for more than an hour? Is there nobody with the leaderships skills to just give everyone free flights and promise everything will be sorted while having people record who worked and who flew and what services were used as best they can? The software failed, just Jerry-rig something up to get people where they need to be, let the accountants and programmers clear up the mess after the…

It's so simple, why didn't this entire company full of experienced specialists just do the random idea I just came up with without thinking about it at all?

Somebody once said "the H in HN stands for hubris" and I often find it painfully accurate.

Re: Ask HN: What's Happening at Southwest?

#29

Post by grantc »

hrunt wrote: post #13
mtmail wrote: post #2

Via reddit/r/bestof https://old.reddit.com/r/flying/comments/zw5lsl/southwest_pi... "So the storm came and it impacted ground ops so bad that many many crews were now “unaccounted” for and the system in place couldn’t keep up. Then it happened for several more days. By Xmas evening the CS department had essentially reached the inability to do anything but simple, one off assignments. And to make matters worse, the ph…

> "I used to work for a large company trying to fill the void [huge gap in the market for good aviation scheduling software], and our software was damn good too. SW was one of the airlines interested, we would demo it exactly like the scenario today, but it was "too expensive" and they stayed on their homebuilt stuff." This is a common situation in any industry. A company has a solution it self-developed in its infan…

It can be cost-driven, but it's just as likely to be complexity-gated (w/ cost frequently being implementation driven and a proxy for complexity). The cost comes from actually unwinding a gnarly legacy system (that may be less than well understood) and making the successor system work. Also, Gall's law has entered the chat:

A complex system that works is invariably found to have evolved from a simple system that worked. A complex system designed from scratch never works and cannot be patched up to make it work. You have to start over with a working simple system.

Re: Ask HN: What's Happening at Southwest?

#30

Post by bena »

From what I've gathered, Southwest effectively performs Just-In-Time resource management.

They arrange flights and crews so that the right number of planes and people are in the right places at the right times.

There's some tolerance in the system. So if the plane from New York to Cincinnati is late, it's ok-ish. The flight from Cincinnati to Dallas should be able to make it in time if things aren't too bad. Then the flight from Dallas to Phoenix should take off when it should. The Phoenix to Las Vegas flight will never know there was a problem.

It also matters for crew. Pilots can only fly for so many hours. So if you have someone stuck in a holding pattern, that cuts into times.

However, if that plane from New York to Cincinnati shits the bed, it'll fuck over Cincinnati to Dallas, Dallas to Phoenix, and Phoenix to Las Vegas. The failure just cascades. You lose planes, you lose crews, nothing is matching up and everything is fucked.

Now imagine this happens a few hundred times. Thousands of flights are affected.

Other airlines don't have this problem because they can just not do a flight. They fly people into a hub, then out of a hub. Delta will go from New York to Atlanta, and back again. Cincinnati to Atlanta, and back again. They work more like a busses. Miss a bus, catch the next one. So if you crap out a day's of flights, you can still put those people on planes and get them out. You know they're either at the hub or on their spoke. So if they're not in Atlanta, they're in their city.

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