B737 flight crew experiences flap asymmetry during approach and executes go around. Flaps are mistak...

Attributes
ACN	808254
Time
Date	200810
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 1400
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : zzz.tracon
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 86 flight time type : 1600
ASRS Report	808254
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 251
ASRS Report	808646
Events
Anomaly	aircraft equipment problem : critical non adherence : far non adherence : published procedure
Independent Detector	aircraft equipment other aircraft equipment : flap position indicator other flight crewa
Resolutory Action	flight crew : executed go around flight crew : overcame equipment problem
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Aircraft

Narrative:

On final approach we noticed the flaps were not extending; indicating 0 flaps. There was a 1-2 degree split between the flaps in the up position indicated by the gauge. We executed a go around and accomplished the asymmetrical flight control checklist. We landed uneventfully and were unaware of a mistake until after we landed and reviewed the checklist on the ground. We misinterped step 2 and lowered the flaps to 15 degrees. With asymmetric flaps; we should have left the flaps in the original setting. Crew coordination could have been better with assigning tasks giving both pilots the opportunity to review the checklist before accomplishing the checklist. Supplemental information from acn 808646: after reviewing the checklist on the ground after the incident; I realized my error. In retrospect; I realize I rushed myself and did not thoroughly read the checklist which ultimately led to my error. In addition; my decision to begin applying the checklist while the first officer was flying removed him from the process. While it was a good decision to bring him back into the process; I should have had him begin the checklist from the top instead of picking up from where I left off which would have highlighted my mistake. To prevent this problem in the future I will stress good crew checklist discipline and thorough review of the procedures before application of the checklist.

Original NASA ASRS Text

Title: B737 FLT CREW EXPERIENCES FLAP ASYMMETRY DURING APPROACH AND EXECUTES GAR. FLAPS ARE MISTAKENLY LOWERED TO 15 USING ALTERNATE FLAP SWITCH WHILE PERFORMING QRH PROCEDURE.

Narrative: ON FINAL APCH WE NOTICED THE FLAPS WERE NOT EXTENDING; INDICATING 0 FLAPS. THERE WAS A 1-2 DEG SPLIT BTWN THE FLAPS IN THE UP POS INDICATED BY THE GAUGE. WE EXECUTED A GAR AND ACCOMPLISHED THE ASYMMETRICAL FLT CTL CHKLIST. WE LANDED UNEVENTFULLY AND WERE UNAWARE OF A MISTAKE UNTIL AFTER WE LANDED AND REVIEWED THE CHKLIST ON THE GND. WE MISINTERPED STEP 2 AND LOWERED THE FLAPS TO 15 DEGS. WITH ASYMMETRIC FLAPS; WE SHOULD HAVE LEFT THE FLAPS IN THE ORIGINAL SETTING. CREW COORD COULD HAVE BEEN BETTER WITH ASSIGNING TASKS GIVING BOTH PLTS THE OPPORTUNITY TO REVIEW THE CHKLIST BEFORE ACCOMPLISHING THE CHKLIST. SUPPLEMENTAL INFO FROM ACN 808646: AFTER REVIEWING THE CHKLIST ON THE GND AFTER THE INCIDENT; I REALIZED MY ERROR. IN RETROSPECT; I REALIZE I RUSHED MYSELF AND DID NOT THOROUGHLY READ THE CHKLIST WHICH ULTIMATELY LED TO MY ERROR. IN ADDITION; MY DECISION TO BEGIN APPLYING THE CHKLIST WHILE THE FO WAS FLYING REMOVED HIM FROM THE PROCESS. WHILE IT WAS A GOOD DECISION TO BRING HIM BACK INTO THE PROCESS; I SHOULD HAVE HAD HIM BEGIN THE CHKLIST FROM THE TOP INSTEAD OF PICKING UP FROM WHERE I LEFT OFF WHICH WOULD HAVE HIGHLIGHTED MY MISTAKE. TO PREVENT THIS PROB IN THE FUTURE I WILL STRESS GOOD CREW CHKLIST DISCIPLINE AND THOROUGH REVIEW OF THE PROCS BEFORE APPLICATION OF THE CHKLIST.

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.

B737 flight crew experiences flap asymmetry during approach and executes go around. Flaps are mistakenly lowered to 15 using alternate flap switch while performing QRH procedure.