MD80 flight crew flying in precipitation at 15000 ft reports wide fluctuations in first officer's ai...

Attributes
ACN	752701
Time
Date	200709
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 15000
Environment
Flight Conditions	IMC
Weather Elements	Rain Turbulence Snow
Light	Dusk
Aircraft 1
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
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	752701
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	752702
Events
Anomaly	aircraft equipment problem : critical inflight encounter : weather other anomaly
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : overcame equipment problem
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

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.

MD80 flight crew flying in precipitation at 15000 ft reports wide fluctuations in first officer's airspeed. First officer's pitot heat circuit breaker is found to be popped.