Here is a breakdown of the distances of possible interisland nonstop routes on WN:
HNL-KOA - 163 mi
LIH-OGG - 201 mi
LIH-KOA - 263 mi
Of the three possible interisland nonstop routes listed above, the LIH-KOA nonstop route is actually longer than 30 of the existing WN nonstop routes in the contiguous U.S. Southwest also already does fly 737-800's and 737 MAX 8's on some flights that are shorter than the LIH-KOA nonstop route.
I doubt you will see them fly any routes that don't touch HNL, especially LIH-KOA--the market is much too small. HA only started LIH-KOA within the past year or so. The interisland routes they offer will be focused on HNL-LIH/OGG/KOA because that is where the vast majority of the traffic is. In terms of interisland flights that do not touch HNL, there are very few on HA ... 1 KOA-LIH, 3 OGG-KOA, 5 OGG-LIH, 2 OGG-ITO. Thats barely 10% of HA's daily interisland flights. The majority of the traffic is on HNL-OGG & HNL-LIH which are 100 miles each.
Keep in mind WN is going to be flying 175 seat aircraft, which is quite a bit bigger than HA's 717s. I still think WN's interisland operation will be mainly triangle routes (OAK-OGG-HNL-SJC) or tag ons (OAK-HNL-LIH-HNL-OAK), mostly mid-day when the tourists fly. They will probably keep HA's fares in check (FYI, I think HA's fares are VERY reasonable), but I don't think WN will be able to compete with HA on schedule or frequency...atleast in terms of when locals fly. If anything, this may spur HA to create a way for kama'aina to get free checked bags interisland (similar to Alaska's Club 49), which wouldn't be the worst thing.
Gate space (at HNL in particular) is going to be a big problem too. Since all gates are CUTE, WN will not be able to permanently install their boarding system "hardware." Are there other airports where WN has portable boarding "hardware?" I'm curious how they handle it. I love open seating and the WN Boarding system, but I have never seen it executed in a CUTE airport.
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