diff --git a/src/aeros_simulation/router.py b/src/aeros_simulation/router.py
index bb3ccfa..fd016fa 100644
--- a/src/aeros_simulation/router.py
+++ b/src/aeros_simulation/router.py
@@ -74,6 +74,7 @@ async def get_simulation(db_session: DbSession, simulation_id):
 async def run_simulations(
     db_session: DbSession,
     simulation_in: SimulationInput,
+    background_tasks: BackgroundTasks
 ):
     """RUN Simulation"""
 
@@ -81,43 +82,54 @@ async def run_simulations(
         db_session=db_session, simulation_in=simulation_in
     )
     simulation_id = simulation.id
-    
-    # simulation_id = "efa8ef4c-0417-4d2d-95f3-41e4283737ab"
 
     project = await get_project(db_session=db_session)
 
-    try:
-        sim_data = simulation_in.model_dump(exclude={"SimulationName", "IsDefault"})
-        sim_data["HubCnnId"] = str(simulation_id)
-        sim_data["projectName"] = project.project_name
+    sim_data = simulation_in.model_dump(exclude={"SimulationName", "IsDefault"})
+    sim_data["HubCnnId"] = str(simulation_id)
+    sim_data["projectName"] = project.project_name
 
+    # Prepare async background task
+    async def run_full_simulation():
+        try:
+            results = await update_equipment_for_simulation(
+                db_session=db_session,
+                project_name=project.project_name,
+                schematic_name=simulation_in.SchematicName,
+                custom_input=simulation_in.CustomInput,
+            )
 
-        # # ##background_tasks.add_task(execute_simulation, db_session=db_session ,simulation_id=simulation_id, sim_data=sim_data)
+            await execute_simulation(
+                db_session=db_session,
+                simulation_id=simulation_id,
+                sim_data=sim_data,
+                is_saved=True,
+                eq_update=results,
+            )
 
-        results = await update_equipment_for_simulation(
-            db_session=db_session, project_name=project.project_name, schematic_name=simulation_in.SchematicName, custom_input=simulation_in.CustomInput
-        )
+            await calculate_plant_eaf(
+                db_session=db_session,
+                simulation_id=simulation_id,
+                is_default=simulation_in.IsDefault,
+                konkin_offset=simulation_in.Konkin_offset,
+            )
 
-        await execute_simulation(
-            db_session=db_session, simulation_id=simulation_id, sim_data=sim_data, is_saved=True, eq_update=results
-        )
-        
-        await calculate_plant_eaf(db_session=db_session, simulation_id=simulation_id, is_default=simulation_in.IsDefault, konkin_offset=simulation_in.Konkin_offset)
-        
-        result = await update_contribution_bulk_mappings(db_session=db_session, simulation_id=simulation_id)
-        
+            await update_contribution_bulk_mappings(
+                db_session=db_session, simulation_id=simulation_id
+            )
 
-        return {
-            "data": str(simulation_id),
-            "status": "success",
-            "message": "Simulation created successfully",
-        }
+        except Exception as e:
+            # TODO: log error into DB or logger
+            print(f"Simulation {simulation_id} failed: {e}")
 
-    except Exception as e:
-        raise HTTPException(
-            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail=str(e)
-        )
+    # Add to background
+    background_tasks.add_task(run_full_simulation)
 
+    return {
+        "data": str(simulation_id),
+        "status": "success",
+        "message": "Simulation started successfully",
+    }
 
 @router.get(
     "/result/calc/{simulation_id}",