A B767 flight crew reported they allowed the airspeed to slow too much while turning final resulting in a stick shaker and altitude loss of 300 ft.
Synopsis
A B767 flight crew reported they allowed the airspeed to slow too much while turning final resulting in a stick shaker and altitude loss of 300 ft.
Narrative
We had briefed about the ZZZ arrival and approach challenges before TOD (Top of descent) and as the (FO) (First Officer) PF (Pilot flying); I commenced the final descent. The auto throttle had been deferred before the start of the flight along with the PFD (Primary Flight Display)- HSI (Horizontal Situation Indicator) digital speed tape inoperative as an amber SPD flag was displayed. This aircraft had the older EFIS instrument cluster setup and not the modern flat panel; which caused a slight workload increase in the instrument scan and interpretation as the only reference for airspeed was the analog gauge indicator on the side in this case. As we descended into range while getting vectored around for the approach we experienced strong area wind shifts causing considerable turbulence shaking the aircraft which was forecasted in our TAF report. With the vectors setting us up for a quick and tight intercept I had slowed down respectively and had flaps 5 out while being bounced around by the strong turbulence.When we received our final vector to intercept the localizer course; I set the heading up in the MCP (Mode Control Panel) with speed mode intervened as the autopilot was engaged in the task saturated environment; as the Approach Controller was trying to confirm if we would like to cancel IFR twice in the air at that time and the CA (Captain) (PM) was working the radios to get the frequency change sorted to announce our intentions in ZZZ traffic advisory and turn on the pilot-controlled runway lights as it was dark outside without any clear horizon reference to gauge level flight or pitch. I looked away for a few seconds to check my iPad approach chart to reconfirm the missed approach altitude before the LOC captured and to verify the manual GA N1 thrust ref climb number if needed for the missed with no auto throttles. When I resumed by instrument cross check; the airspeed indicator showed a rapid decay in that short period as we made the turn with changing winds and choppy conditions. I reached for the throttle levers to push it up as the stick shaker activated just then and lasted for about 2 seconds while I simultaneously lowered the nose and powered up to a safe final approach speed with the autopilot kicked off. The recovery was prompt and we had lost about 200 feet while regaining our airspeed to be stabilized and we were about 3000 feet high at this time.I had evaluated for the need of a go around considering the event and we were high and stable while not in any descent for the final approach segment yet. Hence; we discussed that we were in stabilized flight condition to continue without any further threats and proceeded to extend flaps 15 and follow the sequence. we slowly established on the glideslope thereafter and landed the aircraft safely.Suggestion: I will be more vigilant in such scenarios with auto-throttles deferred with the increased instrument scan and will execute the recovery procedure in any non-normal situation as trained in this case.
Second reporter narrative
Slow airspeed caused a momentary stall warning with an immediate recovery on base turn to final. With the autothrottles deferred the airspeed decayed due to compounding factors. Descending to 3300 feet to intercept the final course the event occurred. Recovery was made with approximately 300 feet altitude loss and added power; flaps five were maintained. I believe pattern altitude winds in the area were probably a contributing factor. Flaps 15 were selected after recovery. Landing was normal after configuration and airspeed were stable.I believe area winds could have been a factor near the airport.Suggestion: I should not go heads down in the traffic pattern. I should delay canceling IFR until post landing.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.