> if there's a spike in passenger numbers?

The number of airline passengers goes up every year except for a couple of years where there have been dips due to major world events.

> I would've thought a larger fleet of smaller planes would be less efficient because it increases operational cost and you have more overhead weight to move around.

You'd be wrong. Airline bosses (Willie Walsh? Almost sure it was him) have said it literally costs less to have two 787 fly one after the other than a single A380. The fuel efficiency of twin engine planes compared to 3 or 4 older engines compensates for the lower capacity.

But the 4-engined models can fly more direct routes over oceans and uninhabited areas right? Because of ETOPS. Of course this is not a problem on many routes.

ETOPS is what allows twins to fly routes that would otherwise require trijets or four engines. I'm not sure what the limits are but flights to Hawaii for example are routinely done with twins.

I know, but as far as I know it requires them to stay with 200nm or so of an airport. So they can't take the most direct route. Also for flights over the poles.

I think four engines still have a benefit there. But I guess you don't run a whole airplane model just because it's not economical on 2 or 3 routes.

I have personally flown from Seattle to Hawaii on a 737 MAX. That is 2320nmi. So no, the ETOPS limit is not 200nmi. There's nothing between Seattle and Hawaii but water. You can see AS853 is a nearly straight line from Seattle to Honolulu. If any of that deviation is for ETOPS it is minor.

ETOPS is time based, not distance based. The 777 has been approved by the FAA for ETOPS-330, which is 330 minutes of flight time to the nearest airport on one engine.

The 737 MAX is ETOPS-180, so it only has to be within 3 hours of a suitable airport when running on one engine.

https://flightaware.com/live/airport_status_bigmap.rvt?airpo...

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

https://en.wikipedia.org/wiki/Boeing_737_MAX

https://www.flightradar24.com/data/flights/as853#2ef8bfcb

The 787 has a 330 minute ETOPS certification, so as long as it’s within 6.5 hours of an airport it can fly there.

That’s almost everywhere on the planet except the South Pacific and Antarctica.

Aha ok, I didn't know that. I thought they had to remain within glide distance (and I think this was also the case in the beginning). I haven't flown intercontinentally for a very long time :) And most of it was in 747s.

Glide distance was never a consideration of ETOPS.

Fuel efficiency is one part, but the increased consumer preference for direct flights is another, while the business model for the A380s was basically "ferry all your passengers to the nearest hub on A320s then use A380s to bring them from hub to hub". But instead larger twinjets like the B787 and A350 which could do these direct routes more economically won.

Jumbo jets are not being retired. That term applies to any airplane with two aisles between the seats or a "wide body". Currently produced examples from Boeing are the 767, 777 and 787. The 747 is simply not economical when compared to those newer airframes. Mot of the final run of 747s and I believe of those still in operation are used for cargo operations, this was an expected outcome even in the 1960s, although for different reasons. For airlines it is about running the plane at capacity and minimizing time on the ground. Airlines choose specialized models for the routes they run. The super jumbos are simply too big to be practical or economical.

Fuel economy is one piece of the puzzle. Another major piece is that passengers prefer the flexibility offered by smaller, more frequent flights instead of larger, less frequent flights.

Wendover Productions has a great video on this topic:

Big Plane vs Little Plane (The Economics of Long-Haul Flights) https://www.youtube.com/watch?v=NlIdzF1_b5M

Four engine airliners are 2x more expensive to maintain. The extension of ETOPS to longer distances was their death knell.