I looked at major low-cost airline operating today and noticed they all operate 737 or A320 aircraft. I do know the 737/A320 are well suited aircraft for low-cost operations but why are there no low-cost airlines operating regional jets or turbo prop aircraft? Is there a reason why low-cost airlines operate aircraft in the 737/A320 range and not smaller (or larger) aircraft? Does it have to do with operating costs or generated revenue from the aircraft? Why does a low-cost airline does not use regional jets or turbo props to fly thinner routes where a 737/A320 is too large to use? High frequencies is one of the success factors of low-cost operations, when using a smaller aircraft on thinner routes wouldn't this allow a low-cost airline to still offer higher frequencies with higher loads because of the smaller size of regional jets/turbo props? I also know that low-cost airlines have their fleet based on one aircraft type, does it make much of a difference to operate two aircraft types, like 737 or A320 for the bussy routes and CRJ or ERJ or ATR aircraft for the thinner routes? Air Tran operates the CRJ as well (I know its a partner airline that operates on behalf of Air Tran). Is Air Tran satisfied with their CRJ operations?
I was just wondering whether the regional jet hasn't attracted the intention of low-cost airlines such as EasyJet, Ryanair, Southwest Airlines, JetBlue and the likes. Are these aircraft too small? Does their route network not allow smaller aircraft (or larger ones)? Can we see JetBlue operating the A321 in the future or EasyJet operating CRJ or ERJ aircraft on the thinner routes?