Shuttles changing location will update the area's has_gravity.

code/controllers/supply_shuttle.dm

@@ -6,9 +6,6 @@
 
 var/global/datum/controller/supply_shuttle/supply_shuttle
 
-/area/supply
-	has_gravity = 1
-
 /area/supply/station //DO NOT TURN THE lighting_use_dynamic STUFF ON FOR SHUTTLES. IT BREAKS THINGS.
 	name = "supply shuttle"
 	icon_state = "shuttle3"

code/game/area/Space Station 13 areas.dm

@@ -136,7 +136,6 @@ proc/process_ghost_teleport_locs()
 	lighting_use_dynamic = 0
 	var/push_dir = SOUTH
 	var/destination
-	has_gravity = 1
 
 /area/shuttle/arrival
 	name = "\improper Arrival Shuttle"
@@ -403,11 +402,11 @@ proc/process_ghost_teleport_locs()
 	name = "\improper Syndicate Station"
 	icon_state = "yellow"
 	requires_power = 0
-	has_gravity = 1
 
 /area/syndicate_station/start
 	name = "\improper Syndicate Forward Operating Base"
 	icon_state = "yellow"
+	has_gravity = 1
 
 /area/syndicate_station/southwest
 	name = "\improper south-west of SS13"

code/game/machinery/computer/syndicate_shuttle.dm

@@ -28,6 +28,8 @@
 		var/area/transit_location = locate(/area/syndicate_station/transit)
 		curr_location.move_contents_to(transit_location)
 		curr_location = transit_location
+		curr_location.has_gravity = 0
+		transit_location.has_gravity = 1
 		sleep(SYNDICATE_SHUTTLE_MOVE_TIME)
 
 	curr_location.move_contents_to(dest_location)

code/modules/shuttle/shuttle.dm

@@ -8,6 +8,8 @@ datum/shuttle_manager
 datum/shuttle_manager/New(var/area, var/delay) //Create a new shuttle manager for the shuttle starting area, "area" and with a movement delay of tickstomove
 	location = area
 	tickstomove = delay
+	var/area/A = locate(location)
+	A.has_gravity = 1
 
 
 datum/shuttle_manager/proc/move_shuttle(var/override_delay)
@@ -50,6 +52,9 @@ datum/shuttle_manager/proc/move_shuttle(var/override_delay)
 		fromArea.move_contents_to(toArea)
 		location = toArea.type
 
+		fromArea.has_gravity = 0
+		toArea.has_gravity = 1
+
 		for(var/obj/machinery/door/D in toArea) //Close any doors on the shuttle
 			spawn(0)
 				D.close()