Have to be at an AIRBASE that the town is WHITE FLAG and has ENEMY TROOPS ACTUALLY RUNNING.
So, you up a C-47, recommended to just kick the rudder and turn around on the runway, and take off out towards the trees.
Hopefully escape before the base is captured and the ack then shoots you down...
Next, the enemy MUST then capture the base...
Finally, you land at a friendly field, on pavement, drop the supplies, and exit. ACHIEVED!
The cargo load mini achievements:
1) A load of troops.
2) A load of vehicle supplies.
3) A load of field supplies.
Get all three in any order, separate occasions, and you get the achievement "The last transport is away."
ADD SOME SPICE? ANYTHING YOU LEAVE WITH IS 'FRESHLY DOWN' FOR THE CAPTURING TEAM... unless they kill you then it instantly comes back up?
The idea is that you would probably need help to escape, yeah, some friendly fighter cover clearing YOU for YOU to get the achievement... imagine that!
Video of the first base capture that most of us probably ever saw!
http://www.youtube.com/watch?v=WASr5-mS238(only reeeally need to watch the first minute of it!)
Or call it the 'stole Leia' achievement?
*Editing again: Kill a transport (c47) doing this, and get the achievement "Our first catch of the day!"
(and really the only line in the film is "the FIRST transport is away"...)