|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||1801 To 2400|
|Locale Reference||airport : zzz.airport|
|Altitude||msl single value : 15000|
|Controlling Facilities||artcc : zzz.artcc|
|Operator||common carrier : air carrier|
|Make Model Name||MD-80 Series (DC-9-80) Undifferentiated or Other Model|
|Operating Under FAR Part||Part 121|
|Flight Phase||climbout : intermediate altitude|
|Affiliation||company : air carrier|
|Function||flight crew : first officer|
|Affiliation||company : air carrier|
|Function||flight crew : captain|
oversight : pic
|Anomaly||aircraft equipment problem : critical|
inflight encounter : weather
|Independent Detector||other flight crewa|
other flight crewb
|Resolutory Action||flight crew : overcame equipment problem|
Passing through 15000 ft; first officer's airspeed indication became unreliable; fluctuating from 300 to 140 KTS (standby airspeed also became erratic; but not to the extent of the first officer's). We were in moderate precipitation; moderate turbulence; and OAT was greater than 6 degrees. Pitot heat selector was in the cpt position. Autoplt and the autothrottle disconnected. No lights on the annunciator panel... Checked ammeter for pitot heat... Captain's was normal; first officer and auxiliary read zero amps. Ran the QRH procedure for airspeed/mach indications unreliable. Confirmed the ammeter was zero for first officer and auxiliary pitot heat. Checklist then directed us to the 'appropriate ice abnormal procedure.' turned to the ice section in the QRH and no procedure seemed appropriate for our conditions... So we ran the pitot/stall heater off light. We found first officer's pitot heat circuit breaker out...the auxiliary circuit breaker was in. We reset it; ammeter showed current to both the first officer and auxiliary pitot and airspeed indication returned to normal. Flight command without event. Points to consider: 1) we never got the pitot/stall heater off light on the annunciator panel; even though heating power was lost to first officer's and the auxiliary pitot tube. 2) the first officer pitot circuit breaker restored power to both the first officer and auxiliary pitot heating elements (even though the auxiliary pitot circuit breaker was in). 3) when looking for an unreliable airspeed procedure in the QRH (flight instruments tab); there are 2 checklists to choose from... This ambiguity could cause a flight crew to run the wrong abnormal checklists. 4) the airspeed/mach indications unreliable checklists refers you to run the 'appropriate ice abnormal procedure.' when turning to this section in the QRH; no procedure seemed appropriate to our situation; so we elected to run the pitot/stall heater off checklist even though this light was not illuminated.
Original NASA ASRS Text
Title: MD80 FLT CREW FLYING IN PRECIPITATION AT 15000 FT RPTS WIDE FLUCTUATIONS IN FO'S AIRSPEED. FO'S PITOT HEAT CB IS FOUND TO BE POPPED.
Narrative: PASSING THROUGH 15000 FT; FO'S AIRSPEED INDICATION BECAME UNRELIABLE; FLUCTUATING FROM 300 TO 140 KTS (STANDBY AIRSPEED ALSO BECAME ERRATIC; BUT NOT TO THE EXTENT OF THE FO'S). WE WERE IN MODERATE PRECIP; MODERATE TURBULENCE; AND OAT WAS GREATER THAN 6 DEGS. PITOT HEAT SELECTOR WAS IN THE CPT POSITION. AUTOPLT AND THE AUTOTHROTTLE DISCONNECTED. NO LIGHTS ON THE ANNUNCIATOR PANEL... CHECKED AMMETER FOR PITOT HEAT... CAPT'S WAS NORMAL; FO AND AUX READ ZERO AMPS. RAN THE QRH PROC FOR AIRSPEED/MACH INDICATIONS UNRELIABLE. CONFIRMED THE AMMETER WAS ZERO FOR FO AND AUX PITOT HEAT. CHKLIST THEN DIRECTED US TO THE 'APPROPRIATE ICE ABNORMAL PROC.' TURNED TO THE ICE SECTION IN THE QRH AND NO PROC SEEMED APPROPRIATE FOR OUR CONDITIONS... SO WE RAN THE PITOT/STALL HEATER OFF LIGHT. WE FOUND FO'S PITOT HEAT CB OUT...THE AUX CB WAS IN. WE RESET IT; AMMETER SHOWED CURRENT TO BOTH THE FO AND AUX PITOT AND AIRSPEED INDICATION RETURNED TO NORMAL. FLT COMMAND WITHOUT EVENT. POINTS TO CONSIDER: 1) WE NEVER GOT THE PITOT/STALL HEATER OFF LIGHT ON THE ANNUNCIATOR PANEL; EVEN THOUGH HEATING POWER WAS LOST TO FO'S AND THE AUX PITOT TUBE. 2) THE FO PITOT CB RESTORED POWER TO BOTH THE FO AND AUX PITOT HEATING ELEMENTS (EVEN THOUGH THE AUX PITOT CB WAS IN). 3) WHEN LOOKING FOR AN UNRELIABLE AIRSPEED PROC IN THE QRH (FLT INSTRUMENTS TAB); THERE ARE 2 CHKLISTS TO CHOOSE FROM... THIS AMBIGUITY COULD CAUSE A FLT CREW TO RUN THE WRONG ABNORMAL CHKLISTS. 4) THE AIRSPEED/MACH INDICATIONS UNRELIABLE CHKLISTS REFERS YOU TO RUN THE 'APPROPRIATE ICE ABNORMAL PROC.' WHEN TURNING TO THIS SECTION IN THE QRH; NO PROC SEEMED APPROPRIATE TO OUR SITUATION; SO WE ELECTED TO RUN THE PITOT/STALL HEATER OFF CHKLIST EVEN THOUGH THIS LIGHT WAS NOT ILLUMINATED.
Data retrieved from NASA's ASRS site as of January 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.