Date: 201510
Local time of day: 1201-1800
Location: MSO.Airport, MT
Flight conditions: Mixed
Weather elements / visibility: Icing; Turbulence
Light: Daylight
Aircraft: Medium Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class D MSO
ATC / advisory: Tower MSO
Aircraft component: Ice Detection System
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Situational Awareness; Troubleshooting
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Inflight Event / Encounter Fuel Issue; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
Result: Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft; Weather
Primary problem: Weather

Narrative: Normal descent. Descent was in continuous light intermittent moderate turbulence. Started picking up light to moderate rime ice around 14;000 feet. Ice detector 1 fail message. Referenced QRH and turned ice protection to on per QRH procedure. Flew ILS Z full procedure arc from EBIME IAF in IMC conditions with occasional moderate turbulence. Left IMC and entered VMC approx. 4;000 feet AGL. ATIS prior to descent was KMSO 00000kt 10sm BKN050 OVC060 10/01 A2978 Runway 11 Prior to descent based on ATIS loaded Stall protect ice speeds with plus zero for additive IAW compass SOP for call winds. Vapproach was 141knots.  Around the FAF for ILS Z 11 MSO the wind started to get a little bumpy from gusty conditions. Adjusted Vapproach to plus 5 knots with auto throttles engaged. Auto pilot coupled to approach until approximately 1;500 feet. At 1;000 feet both pilots acknowledged the stabilized approach criteria was met.  At approximately 600 feet the pilots flying noticed the amber airspeed tape was bouncing around. The Pilot Flying (PF) added 5 knots to Vapproach speed for additional protection. In less than one second there was a loss of approximately 10-15 knots airspeed which caused the amber tape to rise and the sticker shaker to engage for less than 1 second. Immediately the PF adding power and the airplane was back to 150 knots and re-stabilized all the while the ILS was always centered on the localizer and glide slope. The PF continued the landing and the landing was uneventful touching down in the touchdown zone with normal braking and reverse. The PF made a command decision to continue the landing based on several factors. The fuel remaining was 3;700 lbs; the initial approach was thru IMS moderate turbulence and moderate icing. The PF did not want to risk making a go around back into IMC with known moderate icing and moderate turbulence with little fuel. Furthermore; ATIS and weather was calling for calm winds and what was experienced was wind shear conditions that were unpredicted and unknown. In the event of a go around the aircraft could have experienced a more severe wind shear condition. It is also noteworthy that there was no wind shear alert generated by the aircrafts alert systems. After the aircraft was landed safely the Pilot Not Flying notified ATC of the windshear condition. The ATIS for departure an hour later was calling for 17 knot gusts and there was two reports for moderate to severe turbulence by two separate Cessna aircraft.  The weather in mountainous environments are very unpredictable. Carrying extra contingency fuel and an alternate would drastically increase safety.


Second narrative: [Report narrative contained no additional information.]


Synopsis: A flight crew reported multiple distractions due to weather and an icing equipment malfunction. These distractions resulted in several speed excursions before the flight was finally stabilized and a successful landing was accomplished.