diff --git a/aman/sys/RecedingHorizonControl.py b/aman/sys/RecedingHorizonControl.py
index b3a6ae3..f64d477 100644
--- a/aman/sys/RecedingHorizonControl.py
+++ b/aman/sys/RecedingHorizonControl.py
@@ -31,11 +31,11 @@ class RecedingHorizonControl:
 
             # find the correct window
             if window.StartTime <= referenceTime and window.EndTime > referenceTime:
-                if i > self.FreezedIndex:
-                    self.AssignedWindow[inbound.Callsign] = [ i, 0 ]
-                    if False == usePTA:
-                        inbound.PlannedArrivalTime = inbound.EarliestArrivalTime
-                    window.insert(inbound)
+                self.AssignedWindow[inbound.Callsign] = [ i, 0 ]
+                if False == usePTA:
+                    inbound.PlannedArrivalTime = inbound.EarliestArrivalTime
+                inbound.FixedSequence = i < self.FreezedIndex
+                window.insert(inbound)
                 inserted = True
                 break
 
@@ -56,7 +56,7 @@ class RecedingHorizonControl:
                     window.insert(inbound)
                     if False == usePTA:
                         inbound.PlannedArrivalTime = max(window.StartTime, inbound.EarliestArrivalTime)
-
+                    inbound.FixedSequence = len(self.Windows) < self.FreezedIndex
                     break
                 lastWindowTime = self.Windows[-1].EndTime
 
@@ -68,12 +68,11 @@ class RecedingHorizonControl:
             index = self.AssignedWindow[inbound.Callsign][0]
             self.AssignedWindow[inbound.Callsign][1] = 0
 
-            # check if we assume the scheduling as fixed
-            if index < self.FreezedIndex:
-                return
-
             plannedInbound = self.Windows[index].inbound(inbound.Callsign)
             plannedInbound.CurrentPosition = inbound.CurrentPosition
+            # ingore fixed updates
+            if True == plannedInbound.FixedSequence or index < self.FreezedIndex:
+                return
             plannedInbound.ArrivalCandidates = inbound.ArrivalCandidates
             plannedInbound.WTC = inbound.WTC
 
@@ -100,6 +99,7 @@ class RecedingHorizonControl:
             self.AssignedWindow.pop(inbound.Callsign)
             self.insertInWindow(inbound, True)
         else:
+            inbound.FixedSequence = index < self.FreezedIndex
             self.Windows[index].Inbounds.sort(key = lambda x: x.PlannedArrivalTime)
 
     def lastFixedInboundOnRunway(self, runway : str):
@@ -165,6 +165,8 @@ class RecedingHorizonControl:
         if 0 != offsetCorrection:
             for callsign in self.AssignedWindow:
                 self.AssignedWindow[callsign][0] -= offsetCorrection
+                if self.AssignedWindow[callsign][0] < self.FreezedIndex:
+                    self.Windows[self.AssignedWindow[callsign][0]].inbound(callsign).FixedSequence = True
 
         # delete the non-updated aircrafts and increase the missed-counter for later runs
         callsigns = []