Narrative:

We were being vectored for an ILS into fort wayne, in. We were cleared to descend to 2200 ft and cleared for the ILS. The captain was flying using the autoplt. We were high (maybe 6000 ft?) so the captain began a 2500 FPM descent. At about 2800 ft we intercepted the localizer and began a turn onto it. At 2500 ft the aircraft was still descending at 2500 FPM, and I said the altitude didn't capture (since the autoplt would have slowed the descent by now if it had. The captain took no action. At 2200 ft I again said 'the altitude didn't capture.' at this time the captain disengaged the autoplt and began to pull up, but by the time he stopped the descent we were only at 1800 ft MSL (about 800 ft AGL?) and the GPWS was yelling 'pull-up, sink-rate, terrain' and kept saying it. The captain instead of climbing back to our altitude which would have silenced the GPWS was more worried about me pulling the circuit breakers for it. Once he intercepted the GS the GPWS silenced without my help. The main cause of this was because the autoplt didn't capture the altitude. There are a few reasons I can think of that caused this. First, there is 1 autoplt which flies either the captain's or first officer's flight director. I am unable to see what the captain has set his flight director to do, and perhaps he failed to select 'altitude select.' second, if the altitude in the altitude select window is changed (in this case lowered) just prior to altitude capture, 'altitude select' is some times knocked off of the flight directors. If this happened however, I should have seen it knock off mine as well and it didn't. (I saw 'altitude selector' in my flight director. Third, we were cleared for the approach and 'approach arm' was selected on both flight directors. Perhaps the captain's flight director was confused as it intercepted the localizer simultaneously with nearing our altitude. In conclusion, it is critical that both pilots monitor the autoplt, and make sure it does as commanded.

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Original NASA ASRS Text

Title: THE RPTR OBSERVED THE CAPT DSND THROUGH THE GS ON AUTOPLT TO 800 FT ABOVE THE GND.

Narrative: WE WERE BEING VECTORED FOR AN ILS INTO FORT WAYNE, IN. WE WERE CLRED TO DSND TO 2200 FT AND CLRED FOR THE ILS. THE CAPT WAS FLYING USING THE AUTOPLT. WE WERE HIGH (MAYBE 6000 FT?) SO THE CAPT BEGAN A 2500 FPM DSCNT. AT ABOUT 2800 FT WE INTERCEPTED THE LOC AND BEGAN A TURN ONTO IT. AT 2500 FT THE ACFT WAS STILL DSNDING AT 2500 FPM, AND I SAID THE ALT DIDN'T CAPTURE (SINCE THE AUTOPLT WOULD HAVE SLOWED THE DSCNT BY NOW IF IT HAD. THE CAPT TOOK NO ACTION. AT 2200 FT I AGAIN SAID 'THE ALT DIDN'T CAPTURE.' AT THIS TIME THE CAPT DISENGAGED THE AUTOPLT AND BEGAN TO PULL UP, BUT BY THE TIME HE STOPPED THE DSCNT WE WERE ONLY AT 1800 FT MSL (ABOUT 800 FT AGL?) AND THE GPWS WAS YELLING 'PULL-UP, SINK-RATE, TERRAIN' AND KEPT SAYING IT. THE CAPT INSTEAD OF CLBING BACK TO OUR ALT WHICH WOULD HAVE SILENCED THE GPWS WAS MORE WORRIED ABOUT ME PULLING THE CIRCUIT BREAKERS FOR IT. ONCE HE INTERCEPTED THE GS THE GPWS SILENCED WITHOUT MY HELP. THE MAIN CAUSE OF THIS WAS BECAUSE THE AUTOPLT DIDN'T CAPTURE THE ALT. THERE ARE A FEW REASONS I CAN THINK OF THAT CAUSED THIS. FIRST, THERE IS 1 AUTOPLT WHICH FLIES EITHER THE CAPT'S OR FO'S FLT DIRECTOR. I AM UNABLE TO SEE WHAT THE CAPT HAS SET HIS FLT DIRECTOR TO DO, AND PERHAPS HE FAILED TO SELECT 'ALT SELECT.' SECOND, IF THE ALT IN THE ALT SELECT WINDOW IS CHANGED (IN THIS CASE LOWERED) JUST PRIOR TO ALT CAPTURE, 'ALT SELECT' IS SOME TIMES KNOCKED OFF OF THE FLT DIRECTORS. IF THIS HAPPENED HOWEVER, I SHOULD HAVE SEEN IT KNOCK OFF MINE AS WELL AND IT DIDN'T. (I SAW 'ALT SELECTOR' IN MY FLT DIRECTOR. THIRD, WE WERE CLRED FOR THE APCH AND 'APCH ARM' WAS SELECTED ON BOTH FLT DIRECTORS. PERHAPS THE CAPT'S FLT DIRECTOR WAS CONFUSED AS IT INTERCEPTED THE LOC SIMULTANEOUSLY WITH NEARING OUR ALT. IN CONCLUSION, IT IS CRITICAL THAT BOTH PLTS MONITOR THE AUTOPLT, AND MAKE SURE IT DOES AS COMMANDED.

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.