Narrative:

During a coupled autoplt ILS approach it was discovered that when the autoplt was disconnected, the G/south information on the pilot's flight director was eliminated. The G/south had to be reselected in order to get the computed G/south information. Mfr was notified of problem and are working on it. They found several other aircraft on the ramp with the same problem. The flight manual explains when the autoplt is disconnected, you should not lose G/south information. We notified our pilots of the hazard and suggest calling out 'autoplt disconnected, G/south selected' whenever disconnecting the autoplt during a coupled approach. Callback conversation with reporter revealed the following: we have been flying this aircraft for 4 yrs and it seems most of my pilots had noted this anomaly, but it had never caused a problem because on a coupled approach the WX is usually down low and the autoplt is not disconnected until very close to the ground and G/south information is not observed once the runway is made and final descent flare is commenced. It could be a hazard, however, and we have changed our callout procedure to accommodate resetting the G/south. Manufacturer is aware of the problem and the aircraft is there now being modified, hopefully to remove this anomaly.

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Original NASA ASRS Text

Title: REPORTER DISCOVERED THAT THIS ACFT WHEN USING COUPLE APCH SYSTEM UPON DISCONNECTING FOR LNDG THE GLIDE SLOPE INFORMATION DISAPPEARED AND HAD TO BE RESET.

Narrative: DURING A COUPLED AUTOPLT ILS APCH IT WAS DISCOVERED THAT WHEN THE AUTOPLT WAS DISCONNECTED, THE G/S INFO ON THE PLT'S FLT DIRECTOR WAS ELIMINATED. THE G/S HAD TO BE RESELECTED IN ORDER TO GET THE COMPUTED G/S INFO. MFR WAS NOTIFIED OF PROB AND ARE WORKING ON IT. THEY FOUND SEVERAL OTHER ACFT ON THE RAMP WITH THE SAME PROB. THE FLT MANUAL EXPLAINS WHEN THE AUTOPLT IS DISCONNECTED, YOU SHOULD NOT LOSE G/S INFO. WE NOTIFIED OUR PLTS OF THE HAZARD AND SUGGEST CALLING OUT 'AUTOPLT DISCONNECTED, G/S SELECTED' WHENEVER DISCONNECTING THE AUTOPLT DURING A COUPLED APCH. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: WE HAVE BEEN FLYING THIS ACFT FOR 4 YRS AND IT SEEMS MOST OF MY PLTS HAD NOTED THIS ANOMALY, BUT IT HAD NEVER CAUSED A PROB BECAUSE ON A COUPLED APCH THE WX IS USUALLY DOWN LOW AND THE AUTOPLT IS NOT DISCONNECTED UNTIL VERY CLOSE TO THE GND AND G/S INFO IS NOT OBSERVED ONCE THE RWY IS MADE AND FINAL DSCNT FLARE IS COMMENCED. IT COULD BE A HAZARD, HOWEVER, AND WE HAVE CHANGED OUR CALLOUT PROC TO ACCOMMODATE RESETTING THE G/S. MANUFACTURER IS AWARE OF THE PROB AND THE ACFT IS THERE NOW BEING MODIFIED, HOPEFULLY TO REMOVE THIS ANOMALY.

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.