It was a one-off fanfare deal (i.e. much lower prices than usual fanfares) to celebrate CX's birthday. The system was just hanging when you tried to make a booking enquiry, I assume because most of HK was trying to book online and the system was overloaded. Pretty much everyone in our office had a window open trying to book. General conclusion was that quite a few hours of productivity were lost across HK that morning. All flights were sold out by lunchtime (when the system finally became available). I'm pretty sure they'd have been sold out within the first half-hour (or less) if the system was actually working. Some "normal" fanfares sell out within minutes so deals this cheap would disappear pretty much instantly. HKers like a bargain.