Large Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Aircraft; Human Factors; ATC Equipment / Nav Facility / Buildings
We were on the visual approach to runway 28. We were level at 1600 MSL on an intercept heading to the FAF on the ILS approach. At the FAF; we heard an audible 'glide slope;' immediately followed by 'obstacle' GPWS annunciation. At that point; the autopilot descended below the glide path. I immediately turned off the autopilot and leveled the aircraft off until we recaptured the glide path both on instruments and verified by airfield PAPI's. We were in VMC throughout the approach and were able to continue approach visually.Intercept final a mile or more prior to the FAF. Ruminate autopilot usage immediately after deviation anomaly is announced.
Cleared visual approach to runway 28 at 4000 ft on left downwind. FO was pilot flying and he set the FAF altitude 1600 ft and began maneuvering for the visual approach. We executed a normal box pattern and intercepted final at 1600 ft at the FAF. We received an autopilot EICAS message and master caution as we intercepted final and momentarily lost the glide slope signal. I looked outside to pick up the runway. The aircraft did not capture the glide slope and continued to descend. The FO disconnected the autopilot and leveled the aircraft just about the same time the PAPI came into view showing 4 read. I looked at the RA and we were 700 ft AGL with a clear view to the runway. We then received a momentary GPWS warning 'Obstacle' that immediately ceased as we returned to a normal glide path for landing. Because it was day VMC and we had a clear view of the runway and the environment we continued the approach to landing. Failure of autopilot to properly capture glide slope and momentary loss of glide slope signal. Delay in disconnection of autopilot to prevent altitude deviation. Momentary loss of SA. Fatigue. As pilot monitoring I should have suggested planning a longer final approach and not intercepting at the FAF when using the autopilot. That would allow more time for both the autopilot to establish a normal descent rate and allow the crew time to identify deviations and maintain better SA.
Air carrier flight crew reported an autopilot and glideslope anomaly during a visual approach to Runway 28 at SYR. This resulted in a descent well below the glideslope just inside the FAF. The autopilot was disengaged and the aircraft was returned to the now stable glideslope and a normal landing ensued.