Flight Crew Air Transport Pilot (ATP)
Distraction; Situational Awareness
Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Unstabilized Approach
Flight Crew Became Reoriented
Human Factors
Returned to [departure airport] as a result of passenger disturbance. Evaluated climb limit weight; runway length limit and elected to land overweight. Declared emergency with ATC. Notified company; requested police and medical. Completed normal and overweight checklists. Elected to land on longest runway. I was PM; FO was PF. Ref speed was rather high on final due to overweight condition. On approach in VMC FO was slightly high on glideslope and slightly fast. In an effort to reduce altitude and airspeed autopilot and auto throttles were disconnected. I was unaware of this. Speed brakes deployed. Speed rapidly decayed; and stick shaker activated. I pushed up the throttles as FO retracted the speed brake. Stick shaker stopped; remainder of approach was stable. I failed to observe the rapidly decaying airspeed due to a minor distraction from ATC.Suggestions: Never a reason to disconnect [autoflight resources]; which if engaged provides protection against low speed excursions. A greater degree of monitoring by PM must occur. Avoid distractions; particularly during an overweight landing. Contributing factor on my behalf was that having VMC with runway in sight; and the situation very much under control lulled me into monitoring at a lower level than I otherwise would have. An awareness of how speed can rapidly decay with speed brakes deployed.
B777-300 Captain reported airspeed became low enough on a hand-flown visual approach to trigger a stick shaker.