Staff travel is a very fragile thing. I checked in on ALT, DXB to MEL, just as the Icelandic volcano started to become annoying. Check in staff said my ticket had been cancelled! Just like that. No recourse for denied boarding, and everything in the Staff Travel Manual on entitlements was revoked. Admittedly, an unusual event, but very expensive for me while I had to pay full fare on another airline to get home.