In trying to assess why passenger usage of the Hilton Head Island Airport has dropped precipitously, don't overlook the simple and the obvious. The Savannah Hilton Head International Airport is a short drive away. Flights out of that airport tend to leave and arrive pretty much on schedule. Flights out of Hilton Head, such as they are, quite simply are a crapshoot. Even if your flight is not canceled at the last minute, not exactly a rare occurrence, delays are all too frequent.
American Airlines demonstrates no commitment to the Hilton Head airport. It is no surprise that passengers choose the ready alternative.