Narrative:

On ILS approach to runway 28L at pittsburg, we had been cleared for the approach. The captain was flying the aircraft (DH DASH8). The captain left the initial altitude of 4000 ft while I was still showing full ILS deflection low. I rechked my frequency and identify and notified the captain at about 3700 ft that I did not have a GS. The captain acknowledged and I rechked both left and right frequencys and idents. Both were good. I checked the monitors. Both showed localizer and GS. The captain's steering bars and GS were centered for approach and my GS was deflected full up. At approximately 2500 ft, the controller advised that he had a low altitude alert. I told the captain that we were low and something was wrong. Before I could acknowledge the controller called another alert. We were breaking out below the clouds. I advised the captain that I had ground contact and he leveled at 2200 ft, approximately 300 ft below the clouds. I told the controller we were level. The controller transmitted a third warning advising to climb. The captain stayed below the clouds and completed a visual approach. I advised the captain that my ILS was corrected and we were 2 1/2 to 3 mi short of the GS and low.

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Original NASA ASRS Text

Title: FAULTY LOC AND GS SIGNAL ON CAPT INST -- BOTH CTRED, SO CAPT STARTED DSCNT, THINKING HE WAS ON THE GS. RPTR FO ALERTED CAPT THAT HIS GS WAS STILL DEFLECTED FULL UP, BUT THE CAPT CONTINUED DSNDING, EVEN WHEN THE CTLR INTERVENED 3 TIMES OF LOW ALT ALERT. AFTER BREAKING OUT OF CLOUDS, THE CAPT LEVELED AND CONTINUED VISUALLY.

Narrative: ON ILS APCH TO RWY 28L AT PITTSBURG, WE HAD BEEN CLRED FOR THE APCH. THE CAPT WAS FLYING THE ACFT (DH DASH8). THE CAPT LEFT THE INITIAL ALT OF 4000 FT WHILE I WAS STILL SHOWING FULL ILS DEFLECTION LOW. I RECHKED MY FREQ AND IDENT AND NOTIFIED THE CAPT AT ABOUT 3700 FT THAT I DID NOT HAVE A GS. THE CAPT ACKNOWLEDGED AND I RECHKED BOTH L AND R FREQS AND IDENTS. BOTH WERE GOOD. I CHKED THE MONITORS. BOTH SHOWED LOC AND GS. THE CAPT'S STEERING BARS AND GS WERE CTRED FOR APCH AND MY GS WAS DEFLECTED FULL UP. AT APPROX 2500 FT, THE CTLR ADVISED THAT HE HAD A LOW ALT ALERT. I TOLD THE CAPT THAT WE WERE LOW AND SOMETHING WAS WRONG. BEFORE I COULD ACKNOWLEDGE THE CTLR CALLED ANOTHER ALERT. WE WERE BREAKING OUT BELOW THE CLOUDS. I ADVISED THE CAPT THAT I HAD GND CONTACT AND HE LEVELED AT 2200 FT, APPROX 300 FT BELOW THE CLOUDS. I TOLD THE CTLR WE WERE LEVEL. THE CTLR XMITTED A THIRD WARNING ADVISING TO CLB. THE CAPT STAYED BELOW THE CLOUDS AND COMPLETED A VISUAL APCH. I ADVISED THE CAPT THAT MY ILS WAS CORRECTED AND WE WERE 2 1/2 TO 3 MI SHORT OF THE GS AND LOW.

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.