This mission is Evacuation 2 in Eastern Europe just past the halfway point of the Campaign.
First objective is to fly to the west side of the city.
Once in range, an ally will inform you that the target is injured. You will switch to the mounted side gun and have to clear the rooftops.
Once you clear the rooftops, the next objective is to head to the tall building by river. Land on top of the building and rescue your men.
Next you will be given orders to destroy two buildings, so use your hover mode and shoot all of the red targets.
Your next and final objective is to fly back to base and land on the runway. Once you do this the achievement will unlock.