Narrative:

While on ILS runway 8R we were level at 3000 ft MSL, 170 KIAS assigned at approximately 15 DME and IMC. We were cleared to maintain 3000 ft until established and cleared the ILS runway 8R approach, 170 KIAS until the FAF. The GS came alive at the appropriate time and we captured the GS. The GS then began to indicate that we were going high and the first officer was correcting (hand flying). At approximately 1800 ft MSL the final controller advised us to check our altitude (still IMC). We acquired the runway visually at 1500 ft MSL. I queried the controller as to whether or not there was an aircraft that infringed upon the ILS critical area for runway 8R and she said 'yes.' I reported a large GS deviation as a result. The WX at the time was reported as wind 080 degrees/07 KTS, visibility 10 mi, 800 ft scattered, 3400 ft scatter, 13000 ft broken, 25000 ft broken, temperature 24/21, altitude 30.12. Although technically the airport was VFR at the time, we had been cleared the ILS and still in IMC when the deviation occurred. In my opinion, the tower controller failed and should have protected the ILS critical area under these conditions.

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Original NASA ASRS Text

Title: A B737-500 CONDUCTING AN IMC ILS FOLLOWED A BOWED GS LOW AFTER GND TFC DISRUPTED THE ILS GS SIGNAL.

Narrative: WHILE ON ILS RWY 8R WE WERE LEVEL AT 3000 FT MSL, 170 KIAS ASSIGNED AT APPROX 15 DME AND IMC. WE WERE CLRED TO MAINTAIN 3000 FT UNTIL ESTABLISHED AND CLRED THE ILS RWY 8R APCH, 170 KIAS UNTIL THE FAF. THE GS CAME ALIVE AT THE APPROPRIATE TIME AND WE CAPTURED THE GS. THE GS THEN BEGAN TO INDICATE THAT WE WERE GOING HIGH AND THE FO WAS CORRECTING (HAND FLYING). AT APPROX 1800 FT MSL THE FINAL CTLR ADVISED US TO CHK OUR ALT (STILL IMC). WE ACQUIRED THE RWY VISUALLY AT 1500 FT MSL. I QUERIED THE CTLR AS TO WHETHER OR NOT THERE WAS AN ACFT THAT INFRINGED UPON THE ILS CRITICAL AREA FOR RWY 8R AND SHE SAID 'YES.' I RPTED A LARGE GS DEV AS A RESULT. THE WX AT THE TIME WAS RPTED AS WIND 080 DEGS/07 KTS, VISIBILITY 10 MI, 800 FT SCATTERED, 3400 FT SCATTER, 13000 FT BROKEN, 25000 FT BROKEN, TEMP 24/21, ALT 30.12. ALTHOUGH TECHNICALLY THE ARPT WAS VFR AT THE TIME, WE HAD BEEN CLRED THE ILS AND STILL IN IMC WHEN THE DEV OCCURRED. IN MY OPINION, THE TWR CTLR FAILED AND SHOULD HAVE PROTECTED THE ILS CRITICAL AREA UNDER THESE CONDITIONS.

Data retrieved from NASA's ASRS site as of July 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.