B757-200
Flight Crew Air Transport Pilot (ATP)
Distraction; Human-Machine Interface; Situational Awareness; Troubleshooting; Communication Breakdown
Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter Weather / Turbulence
Flight Crew Landed As Precaution
Weather; Aircraft; Human Factors
I was the pilot monitoring for the approach. The Captain/pilot flying (PF) had the autopilot and autothrottles engaged and had intercepted the ILS. At approximately 1;500 feet we were visual with the runway so the Captain disengaged the Autopilot; however he was unable to get the Master Warning or Autopilot Disconnect aural siren to stop. He then reconnected the autopilot and unsuccessfully tried again to disconnect the autopilot; however the master Warning and Disconnect Siren would not stop. I also unsuccessfully tried my disconnect switch. At approximately 1;000 AGL; the PF was getting high on the glideslope so I stated to him that he was 'high; fast and the 600 FPM rate of descent was not adequate.'  He did not make any correction nor did he acknowledge me. I then said again; 'Captain; did you hear me!' He stated that he did hear me and then initiated a correction. However; at approximately 600-700 AGL we were still approximately 145 KTS which was approximately 20K above planned approach speed (Vref was 117 + 5K Additive). He stated that he was fast and at 500 feet he intended to go around. At 500 feet we were approximately 15 knots above approach speed......I then called '500 feet; unstable.' He then said 'landing' and continued to land the airplane. It is of my observation that the approach was unstable at 500 feet by approximately 15 KTS fast. A go-around may have been more appropriate than landing the aircraft. However; given the distraction and hindrance to communications between PF and PM from the autopilot Siren; and the fact that there were thunderstorms 7NM off the departure end of the runway; we landed the aircraft.
We further slowed then to about 150-160K. By this time; I believe we were still prior to the FAF. Then; I called for Flaps 25; and finally Flaps 30. Looking to slow to the Vapp; 124K. The checklists were all completed. However; we were above the glideslope (GS) somewhere around here as I visually had picked up the field and runway. I elected to click off the autopilot and at this point the autopilot warning horn started blaring very loudly as I had attempted numerous times to silence it with the yoke disconnect button. I always try and state to the first officer; 'autopilot disconnected' when it's quiet with no warning horn sounding with that double click to do so. He had tried as well with his yoke button with ZERO success. I remember saying 'This doesn't seem to be working out; go-around' around 700 feet AFE. When we did get to just passing the 500 feet AFE; the First Officer said; 'I think it's best that we land.' I quickly reconsidered his plea and had said 'Landing' after it was apparent that the Vapp speed was down to around 130 KIAS. However; we now got below the GS and the PAPI was red/red. The airspeed seemed to actually be dropping even with the autothrottles connected. I cobbed the power a handful and shoved up the throttles to level it out some being that we had a red PAPI; etc... The wind had shifted from about 240 degrees direction to 030 degrees surface winds at about 10-15 KTS. The VSI seemed to never have exceeded 1;000 FPM for the most part during the 5-700 feet AFE and down to the touch down portion of this unstabilized approach and landing. We finally landed successfully and the landing touchdown part was quite normal.
While shooting an ILS approach in stormy weather the flight crew of a B757-200 was distracted by the autopilot disconnect siren that failed to silence after disengaging the autopilot. The approach became unstable but; after considering a go-around; they elected to land due to the distractions of the still blaring siren and the presence of thunderstorms in the area.