[stuart8ol]

We think for a high proportion of routes 50 seats for hydrogen electric propulsion. We heard from a major airline that their network planners always want a smaller plane, for flexibility and a high load factor and the fleet planners always want a large plane for lower CASM and fewer aircraft, that tension has basically landed on the single-aisle size (180-200 seats) for most routes with conventional propulsion. But this changes with the technology as different cost drivers have different rates of change with seat count. A good indicative document is https://ntrs.nasa.gov/api/citations/20160007749/downloads/20..., this is asking "if you were to serve the market with only one plane, how many seats should it have?"

[aidenn0]

It seems like if the fuel costs were to go down, you'd want a larger plane, since crew and maintenance costs would make up a larger fraction of the costs?

[edit]

Looks like the site answers this; reduced maintenance costs when not having a high-temperature turbine are predicted to lead to similar CASM as a 737 despite being about 1/3 the seats.

[stuart8ol]

I think that is a fair statement. You also have to factor in the capital costs, the aircraft purchase price per seat typically increases with aircraft size so it comes down to the balance there, between that cost increasing and other costs decreasing. The scales can tip either way depending on the circumstances. For a 737, we have that capital costs contribute about 40% of the CASM, whereas Crew is 4% and Maintenance is 16%. In conventional aircraft, the efficiency of larger engines really vs smaller ones really push towards larger aircraft.