Keep in mind that there is a HUGE difference between Z class and O class.

- For Skymiles awards and PMUs, as well as most marketing upgrades, standby on the day of departure is not permitted.

- If Z inventory is still avaiable, you CAN confirm your upgrade on the day of departure up to 2 hours prior (e.g. purchase M class on the day of departure and upgrade!)

- If you are not confirmed at all on a given flight (neither O nor N class) you CANNOT standby at the airport.

- If you are travelling on a premium award ticket, and are not confirmed in the desired cabin (O class) but confirmed in coach (N class) can standby at the airport. GRS reference is G*225/35.


Please also see:
http://www.flyertalk.com/forum/showt...=311932&page=3