Who thinks Frontier Airlines needs to upgrade from small Airbuses to bigger Aircraft?
None of the above.
If they need a larger aircraft then it should be the A321 because it is common type rated with the A320/A319/A318.
The 767 is better suite for longer routes. Frontier doesn’t have too many routes over about 5 hours. The A330 is suite for intercontinental flights. Frontier doesn’t really have any of those. The 757 is about the size of the A321 and if they got an aircraft of that size then, as mentioned above, they should go with the A321.
My understanding (and correct me if I’m wrong) is that while the A321 can fit more passengers, its maximum range shorter than the A320, A319, and A318 (the latter they removed from their fleet a few years ago).
B757? not going to get any that don’t have some miles on them, and the B739 is about the same size of it as well, and why go to that when they could keep commonality with the A321 (minus the range issue above). Anything above that is overkill and won’t fit into their business model.
I don’t know what would work best for them outside of what they already have now. Ejets work for them when they feed into their main network. Increasing capacity is a tough call because of how their model is set up. They could benefit from sharklets, but they would still be using the same fleet.
In the end, adding something uncommon to their fleet would be a huge mistake.
BL.
I would also have to say ‘none of the above’.
I agree Frontier needs to stick with Airbus. They should try the A321 though.
Someone should tell Frontier that they no longer have the A318. Check frontierairlines.com/who-we- … irbus-a318
They are going to be gone by the end of this summer. in fact Frontier only has 4 left.
I decided to post this because, My opinion is that small airlines need at-least a few larger aircraft in their fleet to keep things going.
Which is based off your decades of experience in the aviation industry and running an airline, right?
Ha, I wish! 
but no, like I said it was just My opinion about it.
Some airlines like Great lakes Aviation makes their business by flying people to small communities that don’t (shouldn’t) get regular airline service.
Do a little reading before you post opinions. Try this on for size:
dot.gov/policy/aviation-poli … ir-service
Perhaps that can be the beginning of your education in how airlines operate into smaller communities. Bigger isn’t always better.
Frontier has 2 A318 still flying FYI…
Not for long. 
I know…
No market for 318s. The leasing companies are scrapping them for parts.
Frontier tried two different times to set up a feed operation at DEN using 50 seat RJ’s and 70 seat props. Both times it failed. That’s not to say that every market lost money, but enough markets lost enough money to make the whole operation not worth it.
In addition, they have little use for larger aircraft. It takes a lot of feed to fill a large aircraft and Frontier just doesn’t have that in DEN right now, nor are there any viable international markets for them to fly a widebody to from DEN (maybe they could make a Hawaii flight work, but that’s not worth adding a new fleet type).
They’re currently reconfiguring their operations to be more O&D based and de-emphasize the DEN hub (since they’re getting too small to run an efficient hub-and-spoke operation). They’re taking advantage of their strengths, like their ability and experience to fly to the Caribbean and Mexico.