Thats an AONE5 -- hope you weren't relying on paying the AONE3 price! As for your other questions, BA flights in SA operated by Comair do qualify for the 4 BA segments. Surface segments do not count (yet -- maybe with the next rule change). Hard to book segments are those that have few seats per week, for example SCL-SYD used to be 15 seats/week in F (and mayb 3/wk in A), now it is up to 20 seats/week. Compare with JFK-LHR which has several thousand seats per week. LHR-CPT is very difficult seasonally (but LHR-JNB is much easier). As for unflown segments, technically that invalidates the RTW fare and the airline issuing the ticket can recompute at the point-to-point fare and charge you or your travel agent the difference (I worked it out once and the max possible charge is about USD 40,000). In practice it seems to be ignored, but who knows? Litigating the CoC in the jurisdiction where the fare was purchased isn't a particularly attractive option.