checking availability on KVS can help you determine which flight may have a better chance of an upgrade.

how does one join kvs to use it to check flights? pray tell.

From what I understand, some American FFP for domestic flights offer automatic, unlimited upgrades based on availability (even in advance - ie: up to 5 days before the flight, etc).

gee I hope ek does that in the future! I was once op uped two tiers on a packed ek 530 dxb-cok flight from Y to F.