Narrative:

En route to ZZZ at FL330 (optimum altitude was FL350) and we were asked to enter holding at waypoint as published. We entered the information in the mcdu and the FMS calculated a holding speed of 230 KTS; 5 KTS above the V minimum (lower foot) speed. I elected and requested to hold at 240 KTS to allow 15 KTS of airspeed higher than vmin. Upon entry into holding; the airspeed started to degrade and continued to degrade below vmin. It was approximately 5 KTS below vmin when it first rolled outbound in holding to level flight and we continued to monitor expecting the airspeed to accelerate back above vmin. The power setting was at climb power but the acceleration rate was slow until it got to the inbound turn where the airspeed again continued to degrade. The aircraft banked at an angle of approximately 23 degrees at which time I selected limiting the autobank controller to 15 degrees to attempt to prevent the airspeed from further degrading. Realizing that we would be unable to maintain altitude we requested an immediate descent to FL290 and a heading of 220 degrees which we immediately received from ATC. I selected level change to FL290 and also selected a heading of 220 degrees. The autoplt remained coupled but the airspeed continued to degrade and consequently we got a stick shaker and an automatic slat extension during our descent to FL290. The autoplt remained coupled and no abrupt inputs were made to both throttles and flight controls during the stick shaker condition. Upon leveloff at FL290 I selected a speed of 300 KTS and received a new clearance from ATC for the northeast arrival into ZZZ. Aircraft flew normal throughout the arrival descent; approach and landing with no flight control issues noted.

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Original NASA ASRS Text

Title: A WDB IN HOLDING AT FL330 DSNDED TO FL290 BECAUSE OF SPD DECAY. AT FL290 IN A TURN THE STICK SHAKER AND AUTO SLAT EXTEND ACTIVATED AS THE ACFT STALLED.

Narrative: ENRTE TO ZZZ AT FL330 (OPTIMUM ALT WAS FL350) AND WE WERE ASKED TO ENTER HOLDING AT WAYPOINT AS PUBLISHED. WE ENTERED THE INFO IN THE MCDU AND THE FMS CALCULATED A HOLDING SPD OF 230 KTS; 5 KTS ABOVE THE V MINIMUM (LOWER FOOT) SPD. I ELECTED AND REQUESTED TO HOLD AT 240 KTS TO ALLOW 15 KTS OF AIRSPD HIGHER THAN VMIN. UPON ENTRY INTO HOLDING; THE AIRSPD STARTED TO DEGRADE AND CONTINUED TO DEGRADE BELOW VMIN. IT WAS APPROX 5 KTS BELOW VMIN WHEN IT FIRST ROLLED OUTBOUND IN HOLDING TO LEVEL FLT AND WE CONTINUED TO MONITOR EXPECTING THE AIRSPD TO ACCELERATE BACK ABOVE VMIN. THE PWR SETTING WAS AT CLB PWR BUT THE ACCELERATION RATE WAS SLOW UNTIL IT GOT TO THE INBOUND TURN WHERE THE AIRSPD AGAIN CONTINUED TO DEGRADE. THE ACFT BANKED AT AN ANGLE OF APPROX 23 DEGS AT WHICH TIME I SELECTED LIMITING THE AUTOBANK CTLR TO 15 DEGS TO ATTEMPT TO PREVENT THE AIRSPD FROM FURTHER DEGRADING. REALIZING THAT WE WOULD BE UNABLE TO MAINTAIN ALT WE REQUESTED AN IMMEDIATE DSCNT TO FL290 AND A HDG OF 220 DEGS WHICH WE IMMEDIATELY RECEIVED FROM ATC. I SELECTED LEVEL CHANGE TO FL290 AND ALSO SELECTED A HDG OF 220 DEGS. THE AUTOPLT REMAINED COUPLED BUT THE AIRSPD CONTINUED TO DEGRADE AND CONSEQUENTLY WE GOT A STICK SHAKER AND AN AUTO SLAT EXTENSION DURING OUR DSCNT TO FL290. THE AUTOPLT REMAINED COUPLED AND NO ABRUPT INPUTS WERE MADE TO BOTH THROTTLES AND FLT CTLS DURING THE STICK SHAKER CONDITION. UPON LEVELOFF AT FL290 I SELECTED A SPD OF 300 KTS AND RECEIVED A NEW CLRNC FROM ATC FOR THE NE ARR INTO ZZZ. ACFT FLEW NORMAL THROUGHOUT THE ARR DSCNT; APCH AND LNDG WITH NO FLT CTL ISSUES NOTED.

Data retrieved from NASA's ASRS site as of May 2009 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.