Excellent question. I am uncertain about the Standby List, but I would say yes / no for the Upgrade List.

AS’ website for complimentary upgrades state that one will be upgraded immediately once U space becomes available; however, the UG professor doesn’t always function or even function in a timely manner. So, U space may sit open between T-120 and Gate Control, allowing a pax to manually utilize that U space via GGUs. And, the AS page for GGUs only state that U space need be available. In theory, if between T-120 and Gate Control, pax on the FC UG list should always be upgraded until the list is exhausted.

However, at gate control I believe the UG processor is no longer involved and the gate agents are manually processing the list.

In my mind, if applying a GGU prior to T-120 — No, between T-120 and Gate Control — Yes, and during Gate Control - No.

Just my two ants.. 🤙🏻🍹