Narrative:

While on vectors for the ILS to 27L, the controller advised us to descend to 3500' on the downwind leg. About 17 DME we were turned from base to final. We were asked to reduce to 170 KTS and then to 160 KTS. We were instructed to descend to 2700' (which is 100' lower than printed on the approach plate). We were then asked to decrease to 140 KTS. At this point we were approximately 8 DME and we began the 'final landing' checklist. The captain was tuned to the atl VOR for DME to identify depot and the first officer was tuned to the localizer. The first officer continued to descend when he believed he had intercepted the glide slope. Shortly after the controller advised us to 'check altitude' and climb and maintain 2800' and reduce to final approach speed. At the same moment of the controller's advisory we broke out visually and had the field in sight. With the controller's advisory, I immediately looked at the first officer's instruments to see why we were being asked to climb and the first officer stated that he was following the glide slope. I switched from the atl VOR to the localizer to confirm the first officer's instruments and found him to be below the glide slope and advised him of such. I switched back to the atl VOR which at that moment was indicating about 6.5 DME. I told the first officer we were just approaching depot. I advised the controller that we had ground contact to which he responded and gave us the tower frequency. We advised the tower that we had the field in sight and were cleared to land.

Google
 

Original NASA ASRS Text

Title: AIR CARRIER FLT DESCENDS BEFORE GLIDE SLOPE INTERCEPT.

Narrative: WHILE ON VECTORS FOR THE ILS TO 27L, THE CTLR ADVISED US TO DSND TO 3500' ON THE DOWNWIND LEG. ABOUT 17 DME WE WERE TURNED FROM BASE TO FINAL. WE WERE ASKED TO REDUCE TO 170 KTS AND THEN TO 160 KTS. WE WERE INSTRUCTED TO DSND TO 2700' (WHICH IS 100' LOWER THAN PRINTED ON THE APCH PLATE). WE WERE THEN ASKED TO DECREASE TO 140 KTS. AT THIS POINT WE WERE APPROX 8 DME AND WE BEGAN THE 'FINAL LNDG' CHECKLIST. THE CAPT WAS TUNED TO THE ATL VOR FOR DME TO IDENT DEPOT AND THE F/O WAS TUNED TO THE LOC. THE F/O CONTINUED TO DSND WHEN HE BELIEVED HE HAD INTERCEPTED THE GLIDE SLOPE. SHORTLY AFTER THE CTLR ADVISED US TO 'CHECK ALT' AND CLIMB AND MAINTAIN 2800' AND REDUCE TO FINAL APCH SPEED. AT THE SAME MOMENT OF THE CTLR'S ADVISORY WE BROKE OUT VISUALLY AND HAD THE FIELD IN SIGHT. WITH THE CTLR'S ADVISORY, I IMMEDIATELY LOOKED AT THE F/O'S INSTRUMENTS TO SEE WHY WE WERE BEING ASKED TO CLIMB AND THE F/O STATED THAT HE WAS FOLLOWING THE GLIDE SLOPE. I SWITCHED FROM THE ATL VOR TO THE LOC TO CONFIRM THE F/O'S INSTRUMENTS AND FOUND HIM TO BE BELOW THE GLIDE SLOPE AND ADVISED HIM OF SUCH. I SWITCHED BACK TO THE ATL VOR WHICH AT THAT MOMENT WAS INDICATING ABOUT 6.5 DME. I TOLD THE F/O WE WERE JUST APCHING DEPOT. I ADVISED THE CTLR THAT WE HAD GND CONTACT TO WHICH HE RESPONDED AND GAVE US THE TWR FREQ. WE ADVISED THE TWR THAT WE HAD THE FIELD IN SIGHT AND WERE CLRED TO LAND.

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.