Date: 201203
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: B737-700
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Initial Climb
Airspace: Class C ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Leading Edge Flap
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Troubleshooting
Second reporter function: First Officer
Anomaly: Aircraft Equipment Problem Less Severe
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition; Flight Crew Diverted; General Declared Emergency
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Retracting flaps on schedule after takeoff; LE Flaps Transit light remained illuminated with trailing edge flaps in the up position. Ran the QRH checklist; which in our circumstance allowed for cycling flaps to position one and then up in an effort to correct the indication. The procedure produced no immediate result; but after a period of approximately seven minutes; the indication went to normal. At that point; sent ACARS to Dispatch; stating that I felt a normal landing configuration; as allowed per the QRH; would now be appropriate for landing at [destination]. Dispatch agreed. While configuring [for approach] all indications was normal until flaps 15 were selected. At that point; LE Flaps Transit light illuminated as the trailing edge flaps went to position 15. At airspeed of approximately 152 KTS; the aural warning 'Airspeed Low' sounded. A go-around was initiated with a climb to 3;000 FT. We requested vectors for a ten mile downwind. Ran the QRH Leading Edge Flap Transit Light Illuminated Checklist; ran OPC data; briefed flaps 15 landing; and accomplished the Descent Checklist. Fuel at this point was approximately 6;000 LBS. Stopping margin was approximately 750 FT with maximum braking; target speed was 149 KTS. I briefed the First Officer that if we were unable to maintain the OPC generated target speed without the 'Airspeed Low' Aural Warning sounding; we will divert. After configuring to flaps 15 and while slowing to 149 KTS; the 'Airspeed Low' Aural Warning sounded at approximately 153 KTS. I executed a go-around; and the First Officer requested vectors for [a nearby airport with longer runways]. We received vectors and a climb to 6;000 FT. We were asked by ATC if we would like to declare an emergency and we did. We ran all data and checklists as before; briefed [Approach]; and sent a message to Dispatch. The OPC generated an adequate stopping margin with minimum braking and no requirements for using brake cooling procedures. I briefed the First Officer that I would fly ten knots above target speed all the way to landing flare and would use Autobrakes 3 as a compromise to provide adequate stopping margin and avoid generating excessive brake temperatures. Landing was uneventful. Fuel at landing was approximately 4;800 LBS. Although not required; emergency vehicle took brake temperature measurements after landing. Temperatures were well within limits. Subsequent taxi to gate and parking was uneventful. Company Mechanics told us that erroneous signals related to slat #5 were sent to other aircraft computer systems; which caused the aircraft to be unable to sense what flap configuration it was in; which then resulted in erroneous warnings. The reason that this could occur should be addressed.


Second narrative: [Narrative 2 contained no additional information]


Synopsis: A B737-700 flight crew reported LE Flap Transit light after takeoff that went out; only to reappear on arrival. They diverted to a nearby airport that had longer runways and landed without incident.