My experience is a little stale, but I recall from a dozen years ago that all interisland flights of Hawaii Airlines had to go through Honolulu (HNL). Even the short 20-minute flight from Maui to Hilo took a couple of hours because you had to fly to HNL, maybe even change planes, before flying from Honolulu to Hilo. Is that still the case? I may be needing to fly from Kauai to Maui and then from Maui to Hilo. Nothing I can do will change it, but for my peace of mind I'd just like to know what to plan for.