In addition to what Gruntage said, I would like to dare saying it is easy and can be done in two long steps:
- Making C-130 and units: you just create in editor your C-130 plane, name it "plane", set 0 (zero) azimuth, set "flying" special and choose a high rank (e.g. colonel, captain etc.); then you create all passenger units and, for everyone of them, you set "cargo" special, choose a low rank (e.g soldier, corporal etc.) and group it with C-130. Once you get plane and units grouped together, within editor environment you drag the whole stuff above the sea (preferably into right or left side of the map, far far far from the mission area). You will make C-130 to fly endlessly until you call it from sensor.
- Sensor activation and C-130 landing: you create a marker and place it on the south of vertical airport road and name it "plane_spawn"; place that marker at a reasonable distance from the airport because plane needs space to perform landing action. Then you create a trigger activated by NATO (if player unit is NATO soldier) or by East (if player unit is commie) and into activation field you write:
plane setPos getMarkerPos "plane_spawn"; plane land "land"
NOTE: this trick only works with plane landing in vertical road and flying from South to North direction. For example, if you set your mission in Nogova island which has two airports - one with horizontal road and one with vertical road - plane will land only in the airport with vertical road.