Bottom line -- you don't really care, it just a part of the fare (and earns PQDs is eligible), an archaic leftover of the "fuel embargo" of the 1970s.

Some still refer to this as a fuel surcharge but it has nothing to do with fuel -- just an easy way to adjust prices (and for a while not included in calculating certain taxed / commissions).

It is also used by some carriers to add fees/copays to an award ticket, UA does not do this (at this time )