The Aerial Command Center was a mobile chopper used by the private military company Diamond Dogs during the 1980s. The ACC acted as an immediate base outside of Mother Base and also ferried Venom Snake and other operatives to various locations.
Points of interest
The aft section was where the main operative was to be seated. On the walls adjoining the seats were photographs, while the ceiling nearest the seating contained some intel relating to any missions he or she had undergone. It also was able to utilize the iDroid, hence the designation of Aerial Command Center.
This seating area was where Quiet would sit. DD would sit in the walkway between the seats. Venom Snake was once forced to sit at one of the side sections due to Eli taking dibs on the back seat just after Snake captured him.
As the story progresses, and certain conditions are met, pictures will spawn on certain parts of the ACC near were Venom Snake sits, were the player can view them while boarding it. These pictures serve no purpose other than being cosmetic achievements or badges to show the player's progress and they don't appear in cutscenes, (these pictures as units will range from a single photogragh to a cluster of photograhs that are near each other). Emmerich and Quiet's photographs are removed when they leave Diamond Dogs.
-Picture one (cluster) as the main missions are complete a custer or of pictures on a map will spawn on the ACC coling reflecting intel gained through main missions. The main milestones to expand them are the completion of main missions 06, 12, 20, 31.
-Picture 2 (2 photos), a photo of D-Dog as a puppy then another one of D-Dog as a deployable buddy.
-Picture 3 (cluster), first one spawns after sucessfully fulton extract 10 npc soldiers, and the second when after a total of 30 npc soldiers have been fulton extractered.
-Picture 4 (2 photos), spawn when 150 and 400 npc soldiers have been successfully fulton extracted.
-Picture 5 (2 photos), spawn when 5 and 10 prisioners have been successfully fultoned.
-Picture 6 (1 photo), spawns when quiet is available as a buddy.
-Picture 7 (1 photo), spawns when Quiet has 80% bond with the player.
-Picture 8 (cluster), spawns after mission 13 when D-Walker is given to the player as a buddy.
-Picture 9 (cluster), When Emmerich finalizes Battle Gear for deployment for dispatch missions.
-Picture 10 (1 photo), When extracting ten Wild Asses, Karakul Sheep, or Cashmere Goats.
-Picture 11 (1 photo), when extracting ten Grant's Zebras, Okapis, Nubians or Boer Goats.
-Picture 12 (cluster), when you both extracted both a male and female of the Sheep, Cashmere Goat, Nubian, and Boer Goat species; and having at least 30 of the most recent 50 animal extractions be animals of these species.
-Picture 13 (cluster), when you both extracted at least one specimen of the Wild Ass, Grant's Zebra, and Okapi Species; and having at least 30 of the most recent 50 animal extractions be animals of these species.
-Picture 14 (cluster), when you both extracted at least one specimen of the Gray Wolf, African Wild Dog, and Side-Striped Jackal species; and having at least 30 of the most recent 50 animal extractions be animals of these species.
-Picture 15 (cluster), when you have both extracted at least one specimen of the Brown Bear species; and having at least 40 of the most recent 50 animal extractions be animals of these species.
-Picture 16 (cluster), when you have extracted one specimen of all animal species.
Behind the scenes
The Aerial Command Center was first alluded to with various photographs posted by Hideo Kojima on Twitter, showing the inside of a chopper. The name was revealed within the Official PlayStation Magazine and Official Xbox Magazine coverage of Metal Gear Solid V: The Phantom Pain.
A similar location was also utilized in Metal Gear Solid V: Ground Zeroes with a similar function, with the only difference being the layout.
According to Hideo Kojima's notes in the Piggyback Collector's Edition Guide's art gallery, the premise behind the Aerial Command Center's existence in the game was to allow players the option of having a home front if they don't wish to return to Mother Base, exempting instances where it is made mandatory that the player return to Mother Base.
Quiet will flex her body every now and then when equipped as a buddy in the ACC.
When calling for air extraction, and the helicopter is halfway to its landing spot, Quiet will run to the landing spot and act as a defensive scout and she will not board the helicopter until its only in jumping distance.
On the ceiling of the Aerial Command Center, one can see five profile pictures of Militaires Sans Frontières soldiers from Metal Gear Solid: Peace Walker below a photo of Kazuhira Miller. All five are listed as KIA, implying they were the men that accompanied Miller in Afghanistan before they were ambushed and wiped out by the Parasite Unit.