Narrative:

Descending to blue ridge VOR we were given a crossing restriction of 20 mi northeast at 6000 ft. This was somewhat different since we normally get this at 10 mi. We acknowledged and started descent to meet the restriction. While descending, on the captain's side, the ahrs failed. I shallowed the descent and corrected the problem switching to #2 then continued descent. Shortly afterward the high speed warning aural alarm went off. On this aircraft the alarm went off 10 KTS prematurely. A reduction of power and airspeed would normally cancel this alarm in seconds but on this occasion the alarm would not silence. For the next 2 mins we had the high speed warning blaring in the cockpit till we could locate the circuit breaker to disconnect the alarm. With the alarm cancelled, I noticed we'd have difficulty making the crossing restriction and increased rate of descent. At the same time, ZFW also noticed and gave us a vector to lose the altitude and make the restriction. We landed with no further problem. Upon inspection by maintenance it was determined that the alarm problem was caused by failure of captain's airspeed indicator. Other possible contributing factor was, this was the third leg of a section where we dutied in at XA50 am. After an 8 hour reduced rest overnight which had dutied in the day before at XB55 am and flown 7 legs ending at XC05 pm. Another factor was, this was a new type of problem plus the first officer was relatively new in the aircraft and took a little bit of time to find the circuit breaker. Captain was distracted by constant blaring of airspeed warning and helping first officer find the breaker and silencing the alarm.

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Original NASA ASRS Text

Title: AN ACR LTT NEEDED A VECTOR TO MAKE ITS XING RESTRICTION.

Narrative: DSNDING TO BLUE RIDGE VOR WE WERE GIVEN A XING RESTRICTION OF 20 MI NE AT 6000 FT. THIS WAS SOMEWHAT DIFFERENT SINCE WE NORMALLY GET THIS AT 10 MI. WE ACKNOWLEDGED AND STARTED DSCNT TO MEET THE RESTRICTION. WHILE DSNDING, ON THE CAPT'S SIDE, THE AHRS FAILED. I SHALLOWED THE DSCNT AND CORRECTED THE PROB SWITCHING TO #2 THEN CONTINUED DSCNT. SHORTLY AFTERWARD THE HIGH SPD WARNING AURAL ALARM WENT OFF. ON THIS ACFT THE ALARM WENT OFF 10 KTS PREMATURELY. A REDUCTION OF PWR AND AIRSPD WOULD NORMALLY CANCEL THIS ALARM IN SECONDS BUT ON THIS OCCASION THE ALARM WOULD NOT SILENCE. FOR THE NEXT 2 MINS WE HAD THE HIGH SPD WARNING BLARING IN THE COCKPIT TILL WE COULD LOCATE THE CIRCUIT BREAKER TO DISCONNECT THE ALARM. WITH THE ALARM CANCELLED, I NOTICED WE'D HAVE DIFFICULTY MAKING THE XING RESTRICTION AND INCREASED RATE OF DSCNT. AT THE SAME TIME, ZFW ALSO NOTICED AND GAVE US A VECTOR TO LOSE THE ALT AND MAKE THE RESTRICTION. WE LANDED WITH NO FURTHER PROB. UPON INSPECTION BY MAINT IT WAS DETERMINED THAT THE ALARM PROB WAS CAUSED BY FAILURE OF CAPT'S AIRSPD INDICATOR. OTHER POSSIBLE CONTRIBUTING FACTOR WAS, THIS WAS THE THIRD LEG OF A SECTION WHERE WE DUTIED IN AT XA50 AM. AFTER AN 8 HR REDUCED REST OVERNIGHT WHICH HAD DUTIED IN THE DAY BEFORE AT XB55 AM AND FLOWN 7 LEGS ENDING AT XC05 PM. ANOTHER FACTOR WAS, THIS WAS A NEW TYPE OF PROB PLUS THE FO WAS RELATIVELY NEW IN THE ACFT AND TOOK A LITTLE BIT OF TIME TO FIND THE CIRCUIT BREAKER. CAPT WAS DISTRACTED BY CONSTANT BLARING OF AIRSPD WARNING AND HELPING FO FIND THE BREAKER AND SILENCING THE ALARM.

Data retrieved from NASA's ASRS site as of July 2007 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.