diff --git a/aman/sys/Worker.py b/aman/sys/Worker.py
index f52757e..0d4b0ed 100644
--- a/aman/sys/Worker.py
+++ b/aman/sys/Worker.py
@@ -110,9 +110,13 @@ class Worker(Thread):
                                           preceedingRunways = runways, preceedingIafs = iafs,
                                           ants = 5 * len(relevantInbounds), generations = 5 * len(relevantInbounds))
 
+                # run the optimizer outside the locking functions
+                self.releaseLock()
                 # perform the ACO run
                 aco = Colony(relevantInbounds, acoConfig)
                 aco.optimize()
+                self.acquireLock()
+
                 if None != aco.Result:
                     for node in aco.Result:
                         self.RecedingHorizonControl.resequenceInbound(node.Inbound)