Narrative:

On approach to runway 16R at sea, the G/south indicator scalloped +/- 1 DOT on both the captain's and first officer's indicators. The WX was reported at 200' overcast, the RVR was 2200'. Just as the captain called the approach lights and runway in sight, the G/south indicator jumped, showing 2 dots above the G/south. By then we were in visibility contact with the runway and the first officer executed a normal landing. As we touched down, I noticed an large transport, which had executed the ILS in front of us, just crossing the parallel runway (16L). It is my opinion that the large transport, due to reduced sep, interfered with the G/south signal which we were receiving. The G/south receiver in the airplane worked normally subsequently while on an ILS approach into geg.

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Original NASA ASRS Text

Title: COMMUTER EXECUTING ILS TO 16R AT SEA EXPERIENCES ERRATIC GLIDESLOPE RECEPTION.

Narrative: ON APCH TO RWY 16R AT SEA, THE G/S INDICATOR SCALLOPED +/- 1 DOT ON BOTH THE CAPT'S AND F/O'S INDICATORS. THE WX WAS RPTED AT 200' OVCST, THE RVR WAS 2200'. JUST AS THE CAPT CALLED THE APCH LIGHTS AND RWY IN SIGHT, THE G/S INDICATOR JUMPED, SHOWING 2 DOTS ABOVE THE G/S. BY THEN WE WERE IN VIS CONTACT WITH THE RWY AND THE F/O EXECUTED A NORMAL LNDG. AS WE TOUCHED DOWN, I NOTICED AN LGT, WHICH HAD EXECUTED THE ILS IN FRONT OF US, JUST XING THE PARALLEL RWY (16L). IT IS MY OPINION THAT THE LGT, DUE TO REDUCED SEP, INTERFERED WITH THE G/S SIGNAL WHICH WE WERE RECEIVING. THE G/S RECEIVER IN THE AIRPLANE WORKED NORMALLY SUBSEQUENTLY WHILE ON AN ILS APCH INTO GEG.

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.