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Comment by FooBarWidget | Hacker News Reader

There is such a thing as too fast. Flight ticket comparison websites like skyscanner.com insert fake progress delays ("scanning airline website") to make it seem like they're spending a lot of effort to do important work for you. Research has shown that, without that delay, users trust such websites less, or value them less, because the instantaneous response time is equated to less valuable work.

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Wow, I am very different than those users. I just think "how fucking hard can it be to show me the same flight prices you showed me 30 seconds ago," and then switch to Google Flights

As I recall there are (or at least used to be) lots of computationally hard problems in searching for flights. I think it is already somewhat tricky to enumerate all the reasonable routes between two destinations (and back) (and sometimes there are C shaped plans of A->B, then days later B-> C), and then airlines have complex fee structures combining date, time, class (ie fare), loyalty programme memberships, legs, whole route, current demand, etc such that determining the price for a single route is somewhat tricky and searching for the fastest /cheapest route is also not easy (and crucially not reducible: if you have the cheapest flight from A to B, the cheapest return from A to B may not include it)

But maybe the landscape of airline booking/pricing has changed since I got this impression.

I've got first hand experience in this as we are working on it right now.

This problem is largely due to the closed and archaic nature of the GDS systems that are the source of truth. These systems have been running for 40+ years and no one wants to touch them to make substantive changes. As a result, modernisation is attempted via layers on top of layers that just add complexity confusion.

There is a difficult routing and fare calculation problem here, coupled with a distributed consensus problem. While better solutions to this exist or may exist, the biggest hurdles are the organisational ones.

I worked at a GDS and you're pretty close. There's a component of not wanting to change, but when they do they are burdened by their fragile infrastructure and thousands of competing projects. Very small changes would cause defects in one project that one customer uses. While massive bugs are ignored.

Why is the routing and fare calculation a big problem? I can see writing to a legacy system being slow, but I would think there could be constant caching somewhere of the data as it is read by anyone, and thus reads could be mostly fast, making routing calculation fast. Then it would be a matter of checking for validity of chosen routes.

I imagine a big part is just having to talk to the airlines legacy systems. If Skyscanner (et al) had access to all the data, I expect they could compute prices quicker and give better options. I assume this is why Google bought ITA Software.

> and then switch to Google Flights

Which will most likely show non-bookable outdated prices more often... there's always a trade-off. There might also be some browser/geo profiling going on.

> Which will most likely show non-bookable outdated prices more often

Why do you assert that?

Not the OP, but I have personal experience with Google Flights showing non-bookable fares much more often than I’d like/expect.

Certainly because they have to cache results to load the results as fast as they do.

They don't cache them this way.

However, I'm not sure they really changed the engine underneath, and it was always designed as something that then was input to booking sites, often with filters on fares, because QPX (the engine) would show you fares that an agent with full view of GDSes would see - and sometimes the airlines don't want to sell certain fares (it already filtered the special unsellable ones of course, but it couldn't apply arbitrary policy decisions from airlines).

While that's true of many products, I don't think it applies to SkyScanner - searching for air fares, especially aggregating multiple sources is actually really slow. They might be setting a minimum loading time so the search doesn't jump around so much, but it would never be even close to the timescales involved in the post. AFAIK Google is the only one that can do it faster due to having their own 'index'.

I hear this every time TurboTax gets brought up. I think it's a lot healthier to foster good relationships between users and tech so that they don't have to distrust instantaneous actions.

As an aside, I'm also suspicious of research that shows ~100ms as the threshold for "instantaneous" action, because in video games like FPS shooters most players seem to dislike playing on ping that high.

100ms ping is much different than 100ms total latency.

Even locally, FPS games can reach upwards of 100ms latency locally even before hitting the network, so 100ms ping is more like 100+100=200ms of latency. http://renderingpipeline.com/2013/09/measuring-input-latency...

Additionally, we're extra sensitive to things like latency between a tablet pen drawing and it's stroke appearing, or rendering lagging behind VR HMD rotation, or audio latency if we're trying to jam. Even if we register ~100ms as "instantaneous" in a lot of scenarios, it can still cause troubling disconnects between action and result.

John Carmack on VR HMD latency: https://danluu.com/latency-mitigation/

John Carmack noting that depressing a 360 gamepad trigger can take 20ms: https://twitter.com/id_aa_carmack/status/233240260568551425

A Microsoft Research video on tablet input latency, where the effects of 100ms vs 1ms latency are clearly visible: https://www.youtube.com/watch?v=vOvQCPLkPt4

I have the same view. 100ms is fine for actions that require round trip to the server, in particular when you hide the latency the way multiplayer games do. But for things that are just local UI operations, if you're taking longer than 16.7 ms, you're doing something wrong. A typical videogame can update the whole screen and all game logic in less than that.

Please pass this memo on to people who feel the need to animate UI elements to hide laggyness, and then animate into and out of a loading screen (eg. Loading an app on Android).

The difference is the sense of touch vs vision. Touch is the most sensitive sense and the mismatch between it and vision is more noticeable in a video game than clicking buttons on a website. 300ms is actually the instantaneous threshold for non-dynamic interaction (typical website), but it is 1-10 ms for haptic devices.

I remember back in university in the 1990s, someone in sysadmin added some sleep() to the startup script for Netscape with a comment like "pretend we're doing something".

I prefer things to be instantaneous. Slowness suggests it's been cobbled together by incompetents.

But there are lots of other factors involved.

We could get a Sub 300ms Response and Rendered, but if those results were not good, it would be seen as fast but inaccurate. No one complain about Google Results in its early days, it was fast, and comparatively accurate.

There is also a problem of varying response time, in ideal condition, all query and searches should be returned in roughly the same amount of time, that is because user do not understand there is a different in query complexity, to them all query are the same.

Without some sort of animation, user will be surprised to see their work being served and done without them really knowing and noticing, that could be both good and bad in different situations. ( Read Safari Rendering Progress Bar )

You wouldn't happen to have a source handy for said research, would you? Genuinely curious.

Here's one:

https://www.semanticscholar.org/paper/The-Labor-Illusion%3A-...

A known research is opening the network tab and watching nothing happen. You'll find lots of js and css animations though.

> Research has shown that, without that delay, users trust such websites less, or value them less, because the instantaneous response time is equated to less valuable work.

I'm pretty sure jdc was talking about this research, not the specific implementation.

I just took a quick look at Skyscanner and couldn't initially see this happening - do you have a link or example?

It's been a long time since I worked there but there was generally strong opposition to masking any delays.

That said it's frequently necessary to retrieve the latest fare quotes from the airlines (which involves network calls naturally), so that the user doesn't end up clicking through to wildly different pricing/availability -- but departure/arrival/carrier information about flights should generally be displayed without delay (unless things have changed - glad to see an example if so!).

Like those cookie banners where you CAN opt out, but you get a spinner for about 30 seconds while the website pretends it’s soooooo difficult to save your preferences...

Ha. When building a high ticket price “AI” product recently, it definitely occurred to me that some level of slowness in compute time could definitely be a “feature not bug” from the user’s perspective. (eg. AI thinking really hard!) We didn’t have to implement that option in the end (normal solution was sufficiently slow) but there’s definitely merit in not making your product appear trivial.

That does say a lot about the mindset of such sites. Instead of showing off their superior quality and reassuring the users that they are indeed that better than the competition, they would instead lie to the user and offer worse experience.

It is to my great regret that I've come to realise many people want to be lied to.

Which makes ethics even more difficult.

That does say a lot about the users, but not about the request speed.

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