It depends on the kind of travellers. Business travellers are far more price elastic, preferring schedule. Less frequent but larger planes means giving up the

It depends on the kind of travellers. Business travellers are far more price elastic, preferring schedule. Less frequent but larger planes means giving up the most lucrative passengers to your competition. The best aircraft to use is one where you fill every seat and no one with money is left waiting. Having empty seats get very expensive very quickly because you are hauling unused weight in the plane, fuel to carry that weight, fuel to carry that fuel, heavier/bigger landing gear, bigger airport fees (typically based on plane maximum weight), more expensive maintenance etc. There is also the opportunity cost where the bigger plane could be used on a more profitable route. You should see Cathay Pacific flights between London and Hong Kong. For example on Sundays they have the following departures from HKG to LHR: 00:20 00:35 09:10 14:35 23:55 - there is also a 23:55 on the Saturday making that 3 flights in under an hour. All of them are on the 777-300ER. You see something similar for LHR to HKG. Cathay doesn't have any A380s and really seem like they could use a few!