diff --git a/tasks/flightradar24/ingest/preprocess/main.py b/tasks/flightradar24/ingest/preprocess/main.py
index 03ee4a9..9c3f466 100644
--- a/tasks/flightradar24/ingest/preprocess/main.py
+++ b/tasks/flightradar24/ingest/preprocess/main.py
@@ -203,6 +203,21 @@ def get_or_create_flight(conn, aircraft_id: int, callsign: str | None, observed_
         return cur.fetchone()[0]
 
 
+def update_flight_callsign(conn, aircraft_id: int, callsign: str) -> None:
+    """Update callsign on active flight if not already set."""
+    with conn.cursor() as cur:
+        cur.execute(
+            """
+            UPDATE fr24.flights
+            SET callsign = %s
+            WHERE aircraft_id = %s
+              AND status = 'active'
+              AND callsign IS NULL
+            """,
+            (callsign, aircraft_id),
+        )
+
+
 def get_or_create_track(conn, flight_id: int) -> int:
     with conn.cursor() as cur:
         cur.execute(
@@ -343,6 +358,10 @@ def process_batch(conn, packets: list, aircraft_state: dict) -> int:
             aircraft_id = upsert_aircraft(conn, icao24, callsign, now)
             flight_id   = get_or_create_flight(conn, aircraft_id, callsign, observed_at)
 
+            # update callsign on active flight if MSG1 brought a callsign
+            if msg_type == "1" and callsign:
+                update_flight_callsign(conn, aircraft_id, callsign)
+
             # sanity-check: skip obviously invalid coordinates
             if lat is not None and lon is not None and not (-90 <= lat <= 90 and -180 <= lon <= 180):
                 log.warning("Invalid coords icao24=%s lat=%s lon=%s — skipping", icao24, lat, lon)