Be-400 flight crew reported multiple stall warning indications activated while in cruise. The crew r...

Attributes
ACN	1710081
Time
Date	201912
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Beechjet 400
Operating Under FAR Part	Part 91
Flight Phase	Climb
Route In Use	Direct
Flight Plan	IFR
Component
Aircraft Component	Stall Warning System
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 72 Flight Crew Total 9772 Flight Crew Type 237
Person 2
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Instrument Flight Crew Flight Instructor Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Published Material / Policy

Narrative:

Leveling at FL400; stall warning horn; stall warning light and stick shaker activation occurred. Immediately; added full power and disconnected autopilot for stall recovery procedures and gently lowered the nose to recover. In doing so; lost approximately 600 feet from assigned FL400 but had not locked with autopilot 'alts cap' yet. Immediately advised ATC since the aoa on the pilot's side was at .25 in the green and isa at +3. Airspeed was not noted since on the left side since I was focused on aoa in the green and we were in a full stall activation and should not be per the computer information. We were getting misinformation by two separate systems and was confusing to diagnose so quickly but priority was to fly the plane and recover from the stall activation. Co-pilot stated they looked at their airspeed at the moment it happened and stated they saw 165 KIAS. We immediately asked for a lower altitude and return back to the departing airport of ZZZ and land. We were given initial vectors and had the airport visually and landed without further control or stall activation. Once on the ground and about one hour later on ground power unit (gpu); went out to the plane and saw the co-pilot side ahrs system failed with red flags. During flight; no flags or failure conditions noted and all systems were working. Good decision for quick stall recovery within 1 minute of stall activation.crew had good rest and monitoring the aircraft.crew discussed checklist but nothing in the checklist for this scenario exists and used the checklist for descent; approach and landing. We did not activate emergency services at the airport on landing since we had full control authority and no anomalies.

Original NASA ASRS Text

Title: BE-400 flight crew reported multiple stall warning indications activated while in cruise. The crew recovered from the stall promptly; noting a disagreement in information from two systems.

Narrative: Leveling at FL400; Stall Warning horn; stall warning light and stick shaker activation occurred. Immediately; added full power and disconnected autopilot for stall recovery procedures and gently lowered the nose to recover. In doing so; lost approximately 600 feet from assigned FL400 but had not locked with autopilot 'alts cap' yet. Immediately advised ATC since the AOA on the pilot's side was at .25 in the green and ISA at +3. Airspeed was not noted since on the left side since I was focused on AOA in the green and we were in a full stall activation and should not be per the computer information. We were getting misinformation by two separate systems and was confusing to diagnose so quickly but priority was to fly the plane and recover from the stall activation. Co-pilot stated they looked at their airspeed at the moment it happened and stated they saw 165 KIAS. We immediately asked for a lower altitude and return back to the departing airport of ZZZ and land. We were given initial vectors and had the airport visually and landed without further control or stall activation. Once on the ground and about one hour later on ground power unit (GPU); went out to the plane and saw the co-pilot side AHRS System failed with red flags. During flight; no flags or failure conditions noted and all systems were working. Good decision for quick stall recovery within 1 minute of stall activation.Crew had good rest and monitoring the aircraft.Crew discussed checklist but nothing in the checklist for this scenario exists and used the checklist for descent; approach and landing. We did not activate emergency services at the airport on landing since we had full control authority and no anomalies.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Be-400 flight crew reported multiple stall warning indications activated while in cruise. The crew recovered from the stall promptly; noting a disagreement in information from two systems.