Narrative:

I was the pilot flying and the incident occurred while on the ILS to xx. Outside the final approach fix with the flaps selected to 15 and the gear down I noticed a slight split in the flap position indicator needles; the left flap needle indicated approximately 15 and the right somewhere between 12 and 13. This airplane had a write-up some 4 to 5 days earlier regarding an asymmetrical flap problem. I called to the attention of the first officer the slight split and advised him to watch carefully when we selected flaps 25 to see if they responded normally. When 25 was selected the flaps didn't move; he immediately put the handle back to flaps 15. By that time we were talking to tower. I felt I needed time to sort through the various issues and checklists associated with jammed and asymmetrical flaps so I asked the first officer to advise tower that we were executing a go-around. The tower told us to climb straight ahead to 3;000 and then eventually to 4;000. Tower switched us over to departure control and they asked us about our intentions. I told them we were declaring an emergency; wanted vectors to the south and an ILS to yy (I wanted the longer runway). I turned the aircraft over to the first officer found the appropriate checklist in the QRH and methodically completed the QRH checklist. I then called the flight attendants; briefed them on our situation; gave them the emergency items and asked them to do their '30 second' reviews. After briefing the flight attendants I made a PA explaining to the passengers basically that: the reason we made a go-around was due to a mechanical problem with the aircraft that didn't allow us to use normal landing flap settings. For that reason we would land on a different runway. While on downwind; I resumed control of the aircraft; the first officer set up the ILS to 28 and we completed the normal landing checklist. Per the QRH; the flap handle was selected to 10; the flap inhibit switch was selected; and the vref was adjusted up to 160 KTS. I asked the first officer to call company operations and advise them of our emergency status and have them call dispatch. He tried three times on the company frequency and couldn't get through so I told him to disregard. The landing was uneventful; the airfield rescue and fire fighting equipment followed us for a short while; and we taxied to the gate. Both the first officer and I are new to this aircraft. I have approximately 100 hrs and he 200 hrs of 737 time.

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Original NASA ASRS Text

Title: A B737-800 crews describes the events following a trailing edge flap asymmetry indication received on final. An emergency was declared.

Narrative: I was the pilot flying and the incident occurred while on the ILS to XX. Outside the final approach fix with the flaps selected to 15 and the gear down I noticed a slight split in the flap position indicator needles; the left flap needle indicated approximately 15 and the right somewhere between 12 and 13. This airplane had a write-up some 4 to 5 days earlier regarding an asymmetrical flap problem. I called to the attention of the First Officer the slight split and advised him to watch carefully when we selected flaps 25 to see if they responded normally. When 25 was selected the flaps didn't move; he immediately put the handle back to flaps 15. By that time we were talking to Tower. I felt I needed time to sort through the various issues and checklists associated with jammed and asymmetrical flaps so I asked the First Officer to advise Tower that we were executing a go-around. The Tower told us to climb straight ahead to 3;000 and then eventually to 4;000. Tower switched us over to Departure Control and they asked us about our intentions. I told them we were declaring an emergency; wanted vectors to the south and an ILS to YY (I wanted the longer runway). I turned the aircraft over to the First Officer found the appropriate checklist in the QRH and methodically completed the QRH checklist. I then called the Flight Attendants; briefed them on our situation; gave them the emergency items and asked them to do their '30 second' reviews. After briefing the Flight Attendants I made a PA explaining to the passengers basically that: The reason we made a go-around was due to a mechanical problem with the aircraft that didn't allow us to use normal landing flap settings. For that reason we would land on a different runway. While on downwind; I resumed control of the aircraft; the First Officer set up the ILS to 28 and we completed the normal landing checklist. Per the QRH; the flap handle was selected to 10; the flap inhibit switch was selected; and the Vref was adjusted up to 160 KTS. I asked the First Officer to call Company Operations and advise them of our emergency status and have them call Dispatch. He tried three times on the company frequency and couldn't get through so I told him to disregard. The landing was uneventful; the Airfield Rescue and Fire Fighting equipment followed us for a short while; and we taxied to the gate. Both the First Officer and I are new to this aircraft. I have approximately 100 hrs and he 200 hrs of 737 time.

Data retrieved from NASA's ASRS site as of April 2012 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.