It is really hard to understand what is happening.
The Annual report issued in April 2016 showed excellent results. The Chairman stated " The high passenger load factors experienced in the first half of the
year continued in the second half."
Sure there was some warning about premium longhaul demand and decrease in yield. But the overall tone was positive.

Sure oil prices have increased a bit to $50, but the average price in 2016 is not above the average price in 2015. But why the dramatic and sudden change in mood?
CX must be planning some drastic measures and needs this dramatic profit warning following a bleak interim report three weeks ago.