diff --git a/src/data_collection/amsc_awos_sources.py b/src/data_collection/amsc_awos_sources.py
index 33a7f7c3..5d203a05 100644
--- a/src/data_collection/amsc_awos_sources.py
+++ b/src/data_collection/amsc_awos_sources.py
@@ -164,6 +164,7 @@ def _amsc_parse_wind_plate_payload(
     valid_values = []
     observation_time = None
     observation_time_local = None
+    observation_time_epoch = None
     raw_metar = None
 
     for key, raw_row in data.items():
@@ -179,8 +180,22 @@ def _amsc_parse_wind_plate_payload(
         if not points:
             continue
 
-        if observation_time is None:
-            observation_time, observation_time_local = _amsc_parse_utc_time(raw_row.get("OTIME"))
+        row_observation_time, row_observation_time_local = _amsc_parse_utc_time(raw_row.get("OTIME"))
+        row_observation_epoch = None
+        if row_observation_time:
+            try:
+                row_observation_epoch = datetime.fromisoformat(row_observation_time).timestamp()
+            except ValueError:
+                row_observation_epoch = None
+        if row_observation_epoch is not None and (
+            observation_time_epoch is None or row_observation_epoch > observation_time_epoch
+        ):
+            observation_time = row_observation_time
+            observation_time_local = row_observation_time_local
+            observation_time_epoch = row_observation_epoch
+        elif observation_time is None and row_observation_time:
+            observation_time = row_observation_time
+            observation_time_local = row_observation_time_local
         if raw_metar is None and raw_row.get("METAR"):
             raw_metar = str(raw_row.get("METAR"))
 
diff --git a/tests/test_amsc_awos_sources.py b/tests/test_amsc_awos_sources.py
index fa8acaab..96c51074 100644
--- a/tests/test_amsc_awos_sources.py
+++ b/tests/test_amsc_awos_sources.py
@@ -135,6 +135,36 @@ def test_parse_wind_plate_payload_uses_end_temperature_when_target_is_second_run
     assert parsed["runway_obs"]["point_temperatures"][0]["target_runway_max"] == 33.7
 
 
+def test_parse_wind_plate_payload_uses_latest_runway_observation_time():
+    payload = {
+        "code": 200,
+        "data": {
+            "16L/34R": {
+                "RNO": "16L/34R",
+                "OTIME": "2026-06-14 10:44:00",
+                "TDZ_TEMP": "22.0",
+                "MID_TEMP": "22.1",
+                "END_TEMP": "22.2",
+            },
+            "17L/35R": {
+                "RNO": "17L/35R",
+                "OTIME": "2026-06-14 15:43:00",
+                "TDZ_TEMP": "24.9",
+                "MID_TEMP": "25.1",
+                "END_TEMP": "25.4",
+            },
+        },
+    }
+
+    parsed = _amsc_parse_wind_plate_payload(payload, city_key="shanghai", icao="ZSPD")
+
+    assert parsed is not None
+    assert parsed["settlement_runway"] == "35R"
+    assert parsed["temp_c"] == 25.4
+    assert parsed["observation_time"] == "2026-06-14T15:43:00+00:00"
+    assert parsed["observation_time_local"] == "2026-06-14 23:43:00"
+
+
 def test_parse_wind_plate_payload_rejects_unauthorized_or_empty_payloads():
     assert _amsc_parse_wind_plate_payload(
         {"errCode": -12010, "errMsg": "无权访问此接口"},
diff --git a/tests/test_api_performance_timing.py b/tests/test_api_performance_timing.py
index 3b34cab3..728b3323 100644
--- a/tests/test_api_performance_timing.py
+++ b/tests/test_api_performance_timing.py
@@ -129,7 +129,7 @@ def test_scan_terminal_response_includes_backend_server_timing(monkeypatch):
     monkeypatch.setattr(
         scan_api.legacy_routes,
         "build_scan_terminal_payload",
-        lambda filters, force_refresh=False, timing_recorder=None: {
+        lambda filters, force_refresh=False, timing_recorder=None, **_kwargs: {
             "rows": [],
             "filters": filters,
             "status": "ready",
@@ -155,7 +155,7 @@ def test_scan_terminal_stale_response_is_not_cached(monkeypatch):
     monkeypatch.setattr(
         scan_api.legacy_routes,
         "build_scan_terminal_payload",
-        lambda filters, force_refresh=False, timing_recorder=None: {
+        lambda filters, force_refresh=False, timing_recorder=None, **_kwargs: {
             "rows": [],
             "filters": filters,
             "status": "ready",
diff --git a/web/services/latest_observation_overlay.py b/web/services/latest_observation_overlay.py
index 5b017217..0027b4e8 100644
--- a/web/services/latest_observation_overlay.py
+++ b/web/services/latest_observation_overlay.py
@@ -58,13 +58,18 @@ def _block_epoch(block: Any) -> Optional[int]:
 
 
 def _raw_amsc_epoch(row: dict[str, Any], raw_payload: dict[str, Any]) -> Optional[int]:
-    values = (
+    payload_values = (
         raw_payload.get("observation_time"),
         raw_payload.get("observed_at"),
-        row.get("observed_at"),
     )
-    parsed = [epoch for epoch in (parse_observation_epoch(value) for value in values) if epoch is not None]
-    return max(parsed) if parsed else None
+    parsed = [
+        epoch
+        for epoch in (parse_observation_epoch(value) for value in payload_values)
+        if epoch is not None
+    ]
+    if parsed:
+        return max(parsed)
+    return parse_observation_epoch(row.get("observed_at"))
 
 
 def _to_float(value: Any) -> Optional[float]: