Security also seems to be variable enough that you need to add buffer, and then there's the built in incentive to have people sitting around in a shopping mall.
Some airports have good connections. In the last month I've been to Berlin and Brussels, and in each case my train journey into the city was about 15-20 minutes (caveat: I happened to be going to the right side of Berlin for the airport, and the Brussels train, while central, was _bizarrely_ expensive).
Of course, some airports, not so much. Grumble mutter Dublin (there is some hope of a rail line, or possibly _two_ rail lines, in about 2040, but until then it's a choice of painfully slow standard buses (1 hour into city), or expensive unreliable express buses (25 mins into city, if they show up)).
But for many routes, really security, and the sheer poor layout of the airport, is the big slowdown. My favourite for this is London City; the (small, weird) plane lands, you walk out a door, and you are at a DLR stop.
Boarding also always takes far longer than you'd imagine it should, mostly due to people being people. In principle you could board an airliner in a couple of minutes, but only with perfect behaviour from all passengers, so good luck with that.
There was a company about 15 years ago that developed a double ended jetway so you could load and unload from the front and back simultaneously. They said it shaved about 18 minutes from loading and unloading (combined). On the average flight this would be the equivalent of going about 100mph faster for seemingly a simple change.
They installed a few in Denver and I believe in Calgary. Unfortunately one in Denver had a problem and collapsed and hit the wing of a plane, and so they ripped them all out and no one ever tried again.
Ryanair actually orders specialised 737s with built-in airstairs and a few other modifications to facilitate this.
This only really works for 737-sized planes and down, though, where air-stairs are an easy option (AFAIK even A320s can be a bit of a stretch, as they're significantly taller than 737s).
Washington Dulles aka IAD is a fine example. It has a vast security area below deck for regular folks and a smaller one up top where all the Clear and Pre flyers go. That should be inverted.
Then, after security, passengers must walk 300m and change levels to catch a small shuttle train. Or, to take the special mobile lounge bus things. If you take the train, it drops you off 500m from the gate area, so you have tonget off the train, climb the stairs, walk through a tunnel, climb the escalator, and then walk the remainder of the terminal to your gate. It is absolutely laughable how poor Dulles is, esp considering its importance to United.
I don't know why there isn't just a bunch of seats in the terminal laid out the same way as the plane. Sit there and wait, and then when it's time to board, the people at the end get on first, tada, everyone is boarded and we're not stopping each other from getting in.
Anyway, people would just ignore it.
What they should really have is a line for clueless people. You know, the people ahead of you who walk thru metal detectors with belts. Then aw-shucks and waste another 5minutes. Then they forgot to take their laptops out of their bag. Aw-shucks again. Then they want to unlace their shoes.
I'd love to have a line for clued-in travelers and one for people who arent.
Fun times in Texas.
This has always confused me because it seems like it seems like the easiest possible prediction problem. Nearly everyone buys their tickets in advance, often weeks ahead of time.
Why can’t they text you the day before and say “The airport will be quiet/normal/chaotic for your flight tomorrow, so please arrive 1/2/3 hours before takeoff?”
I wouldnt, doesn't matter if airport is in bloody state of war.
On a quiet day I measured 7 minutes from stepping out of the bus and being through security.
Mind you, I'm annoyed at the liquids thing given I used to routinely bring bottles of wine or a local liqueur home in carry-on. And I can't any longer.
Planes land outside the city, taxi to the downtown terminal.
If you're suggesting this hypothetical giant tunnel would actually have the planes taxiing all the way to a whole airport underneath a city... I don't see that solving more problems than it would create.
It would create problems, but the problems would be for the designers and maintainers of the infrastructure, not for the passengers.
Airplanes are not fundamentally that much bigger than trains, which routinely go under the city.
