Why have airline travel times not decreased over the decades?
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Because there’s no faster way to cross the oceans yet, and in America (one of the main places for innovation), we’ve continued to rely on air travel for large distance travel.
Supersonic travel typically requires a far higher fuel consumption per passenger-mile traveled, and supersonic aircraft designs tend to be especially inefficient when not traveling supersonic, which is a problem given that many governments don’t want supersonic travel above populated land due to noise concerns.
As such there’s little demand for supersonic passenger travel, and only one company even trying to make a modern supersonic jet possible.
Long haul flights are already going most of the way to the speed of sound. If you want to go faster, you need a Concorde – and boy, did that poor thing have many, many drawbacks. Going supersonic is also, as one might reasonably think, *not very fuel efficient* and had low capacity. If you want faster flights, be prepared to pay several times the cost of a current ticket.
>ELI5: Why have airline travel times not decreased over the decades?
How fast an airplane can take you anywhere is a direct function of how much fuel it is burning. In order for travel times to decrease, the willingness to pay higher prices [for less efficient but faster planes](https://en.wikipedia.org/wiki/Concorde) would have to go up. It never did.
The market has settled on “I’d rather pay less money than arrive half an hour earlier”.
A couple of reasons.
First, physics. The speed of sound varies with temperature, altitude, and approaching the speed of sound causes physical stresses on the plane. It’s called the “sound barrier” for a reason. That stress will limit a plane’s top speed. It’s actually a published stat in the plane’s instruction manual of what its speed limit is when measuring as a percentage of the speed of sound, alongside more traditional units like miles/hour.
The second is economical. Just like in a car, the faster you go, the more air resistance will try to hold you back and the more fuel you need to burn just to keep your current speed. So going faster does mean more fuel burn. You want a cheaper plane ticket? Then you need the plane to be as economical as possible… Not just the engines being super-efficient, but the plane taking a route and speed that don’t waste fuel either. So airlines are incentivized to NOT go super-fast.
The mother of all tailwinds may let a plane reach its destination ahead of schedule, but that’s just luck.
When commercial jet aircrafts became available we were able to get pretty close to the speed of sound. This is currently what is limiting the speed of commercial airplanes. When you get to the speed of sound and above the fuel economy goes drastically down. You use several times more fuel going mach 1.1 compared to mach 0.9. We are slowly improving fuel economy and therefore the speed which you can afford to fly at, but even with dramatic improvements in fuel economy we have only been able to increase the speed from about mach 0.85 in the 60s to mach 0.9 today. Something that is hardly noticeable.
So to improve flight times we are talking about supersonic airliners. You might remember that there were some such airplane designs based on supersonic bomber airplanes. Just one of these designs saw some commercial success but even then struggled a lot since the ticket price were much higher then on any other aircraft. The good news is that the increased fuel use in supersonic aircrafts is mostly related to effects around the speed of sound. So a supersonic airliner is able to fly almost twice the speed of sound at an economic rate. And we are seeing development of supersonic civilian aircrafts again, although with smaller private jets at first. We could therefore end up with much faster air travel available soon, although at quite a high price.
The faster you go the more fuel you use and the more travel costs.
30 years ago the rich and powerful had to attend meetings in person and needed to have Breakfast in London and Lunch in New York, they could afford to pay a premium for Supersonic travel however now if a face to face meeting is absolutely necessary they can use the Internet or take a first class flight overnight with full sized beds. The industry of air travel has moved onto a more budget model, flying more passengers than ever before by driving prices down so more passengers can afford to fly.
Economics. An A380 has a maximum passenger capacity of 840, assuming it’s all economy, while a Concorde has 128. That’s about 4 times more. Non stop on a regular subsonic jetliner from NYC to London is about 7 hours while with a Concorde is about 3 hours.
When you do the math, not taking into account the extra fuel costs per passenger mile travelled as in the comments below, you get about twice the revenue with an all-economy A380 than a high density Concorde
The main reason is that fuel efficiency is the name of the game with airlines.
The number one differentiator between any two flights between the same airports is price. Time and time again, it’s been found that price is basically the only thing a lot of people consider when choosing an airline to fly on. Having the lowest price matters.
And when you want to have the lowest price, you need to make the flight happen as cheaply as possible, which means flying at the most fuel efficient speed. Anything above about 80% the speed of sound will actually start to become very fuel inefficient, so the practical speed limit for efficiency is kind of locked in.
Now there is one way that airlines do compete for speed, and that is to offer more direct routes. For example, some airlines fly direct routes between multiple east coast cities and Hawaii, even if it could be cheaper to bring everyone through LAX and then put them on potentially fewer trans-pacific flights overall. However, passengers will choose fewer layovers, which is where “speed” is a factor for passengers. A 2 hour layover matters, but 20 minutes of flight time doesn’t.
I actually watched a [short](https://youtube.com/shorts/AktBT6D-ewg?si=C2YqZ378idmcm7Xm) by Hank Green about exactly this subject, just today.
In short, we’ve discovered the optimal speed for flying in planes without drastically driving up fuel requirement.
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