diff --git a/src/adsb/compress_adsb_to_aircraft_data.py b/src/adsb/compress_adsb_to_aircraft_data.py
index 6740932..89585e4 100644
--- a/src/adsb/compress_adsb_to_aircraft_data.py
+++ b/src/adsb/compress_adsb_to_aircraft_data.py
@@ -123,10 +123,7 @@ def compress_multi_icao_df(df: pl.DataFrame, verbose: bool = True) -> pl.DataFra
         # partition_by with as_dict=True returns tuple keys: (date, icao)
         date_val, icao = group_key
         compressed = compress_df_polars(group_df, str(icao))
-        # Set time to start of UTC day for consistent deduplication
-        compressed = compressed.with_columns(
-            pl.lit(date_val).cast(pl.Date).cast(pl.Datetime).alias('time')
-        )
+        # Time is preserved from compress_df_polars (earliest time for this ICAO on this day)
         compressed_dfs.append(compressed)
     
     if compressed_dfs: