diff --git a/src/server/BreCal/validators/input_validation_shipcall.py b/src/server/BreCal/validators/input_validation_shipcall.py
index a6d1555..4a591be 100644
--- a/src/server/BreCal/validators/input_validation_shipcall.py
+++ b/src/server/BreCal/validators/input_validation_shipcall.py
@@ -129,11 +129,14 @@ class InputValidationShipcall():
         if check_if_int_is_valid_flag(flags_value, enum_object=ParticipantFlag):
             raise ValidationError({"flags":f"incorrect value provided for 'flags'. Must be a valid combination of the flags."})
 
+        existing_shipcall = None
         if is_put_data:
-            # the type of a shipcall may not be changed. It can only be set with the initial POST-request.
-            InputValidationShipcall.check_shipcall_type_is_unchanged(loadedModel)
 
-        InputValidationShipcall.check_times_are_in_future(loadedModel, content)
+            existing_shipcall = InputValidationShipcall.get_shipcall_by_id(loadedModel.get("id"))
+            # the type of a shipcall may not be changed. It can only be set with the initial POST-request.
+            InputValidationShipcall.check_shipcall_type_is_unchanged(loadedModel, existing_shipcall)
+
+        InputValidationShipcall.check_times_are_in_future(loadedModel, content, existing_shipcall)
 
         # some arguments must not be provided
         InputValidationShipcall.check_forbidden_arguments(content, forbidden_keys=forbidden_keys)
@@ -261,14 +264,16 @@ class InputValidationShipcall():
             raise ValidationError({"participants":f"every participant id and type should be listed only once. Found multiple entries for one of the participants."})
 
     @staticmethod
-    def check_shipcall_type_is_unchanged(loadedModel:dict):
-        # the type of a shipcall may only be set on POST requests. Afterwards, shipcall types may not be changed.
-        query = SQLQuery.get_shipcall_by_id()
-        shipcall = execute_sql_query_standalone(query=query, model=Shipcall, param={"id":loadedModel.get("id")}, command_type="single")
-
-        if int(loadedModel["type"]) != int(shipcall.type):
+    def check_shipcall_type_is_unchanged(loadedModel:dict, existing_shipcall:object):        
+        if int(loadedModel["type"]) != int(existing_shipcall.type):
             raise ValidationError({"type":f"The shipcall type may only be set in the initial POST-request. Afterwards, changing the shipcall type is not allowed."}) # @pytest.raises
         return
+    
+    @staticmethod
+    def get_shipcall_by_id(shipcall_id:int):
+        query = SQLQuery.get_shipcall_by_id()
+        shipcall = execute_sql_query_standalone(query=query, model=Shipcall, param={"id":shipcall_id}, command_type="single")
+        return shipcall
 
     @staticmethod
     def check_forbidden_arguments(content:dict, forbidden_keys=["evaluation", "evaluation_message"]):
@@ -330,7 +335,7 @@ class InputValidationShipcall():
         return
 
     @staticmethod
-    def check_times_are_in_future(loadedModel:dict, content:dict):
+    def check_times_are_in_future(loadedModel:dict, content:dict, existing_shipcall:object):
         """
         Dates should be in the future. Depending on the ShipcallType, specific values should be checked
         Perfornms datetime checks in the loadedModel (datetime.datetime objects).
@@ -353,11 +358,20 @@ class InputValidationShipcall():
         tidal_window_from = loadedModel.get("tidal_window_from", None)
         tidal_window_to = loadedModel.get("tidal_window_to", None)
 
-        # Estimated arrival or departure times
-        InputValidationShipcall.check_times_in_future_based_on_type(type_, time_ref, eta, etd)
+        if existing_shipcall is not None:
+            existing_eta = existing_shipcall.eta
+            existing_etd = existing_shipcall.etd
+            existing_tidal_window_from = existing_shipcall.tidal_window_from
+            existing_tidal_window_to = existing_shipcall.tidal_window_to
+
+        if eta != existing_eta or etd != existing_etd:
+            # Estimated arrival or departure times
+            InputValidationShipcall.check_times_in_future_based_on_type(type_, time_ref, eta, etd)
+
+        if tidal_window_from != existing_tidal_window_from or tidal_window_to != existing_tidal_window_to:
+            # Tidal Window
+            InputValidationShipcall.check_tidal_window_in_future(type_, time_ref, tidal_window_from, tidal_window_to)
 
-        # Tidal Window
-        InputValidationShipcall.check_tidal_window_in_future(type_, time_ref, tidal_window_from, tidal_window_to)
         return
 
     @staticmethod
diff --git a/src/server/BreCal/validators/input_validation_times.py b/src/server/BreCal/validators/input_validation_times.py
index a6be514..780bdce 100644
--- a/src/server/BreCal/validators/input_validation_times.py
+++ b/src/server/BreCal/validators/input_validation_times.py
@@ -419,6 +419,8 @@ class InputValidationTimes():
         # commonly used in the PUT-request
         if loadedModel is not None:
             (shipcall_id, times_assigned_participant) = InputValidationTimes.prepare_authority_check_for_put_request(loadedModel)
+        else:
+            loadedModel = get_times_data_for_id(times_id)
 
         # commonly used in the DELETE-request
         if times_id is not None: