Delayed Spawn

[Troll2k]

How do you get planes to spawn a certain amount of time after the map starts?

I know I have seen the answer a long time ago but I can not find it now.

Spawn script on?
Custom script?
Trigger?
Action?

[salmo]

1. Select the plane group in fmb.
2. Tick the "spawn on script" checkbox at the bottom of the plane properties tab.
3. Go to the tiggers in the script menu & create a new timed trigger (this is where you specify how much time before spawning)
4. Go to the 'actions' tab in the script menu & create a new action. Select 'airspawngroup' & click on the group you want to spawn.

[Troll2k]

The only choice I see under action type is an"air spawn group".
Is there a ground spawn?