Date: 201405
Local time of day: 1201-1800
Location: MIA.Airport, FL
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B MIA
ATC / advisory: Tower MIA
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Human-Machine Interface
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Fuel Issue
Detector: Automation Aircraft Other Automation; Automation Air Traffic Control; Person Flight Crew; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Separated Traffic; Air Traffic Control Issued Advisory / Alert; Flight Crew Diverted; Flight Crew Executed Go Around / Missed Approach
Contributing factors: Human Factors; Weather
Primary problem: Weather

Narrative: I was pilot flying. Forecast [showed] thunderstorms in south Florida. Planned alternates of PBI and RSW. Planned arrival fuel of 8701 with a reserve + alternate of 6471. Arriving in MIA terminal area given numerous vectors for weather and spacing. Eventually given holding instructions by ATC at EYW. Reviewed weather at planned alternates and bingo fuel. RSW was obvious clear choice as PBI and FLL were getting clobbered with weather which for the most part was north and west of MIA. Clear path to RSW from EYW. Prior to reaching EYW; ATC cancelled our holding and we were again vectored extensively for traffic and weather. Vectored east of field then placed on a right downwind to Runway 9 following a 767. In the clear VFR for the entire approach with a good ride. Turned inside of GRITT and cleared for approach. Runway 9 in sight 7 miles out. Approaching INESS fully configured with gear down and flaps 30; Tower called microburst alert for runways 8L and 8R. We were still in the clear; runway in sight; with a good ride. On landing rollout; 767 that landed in front of us reported windshear to Tower. When Tower queried the aircraft as to whether it was a gain or loss; pilots responded gain and loss with no quantifiable data. At approximately 1;000 feet I turned the autopilot off and informed First Officer we'd add a few knots to our approach speed. At 800 feet AGL we began experiencing airspeed fluctuations and so I turned the autothrottles off as well. At 500 feet AGL the aircraft alerted us with a windshear warning and we abandoned the approach executing the windshear escape procedure. Upon exiting the area of concern we continued with a normal cleanup and were vectored south by Departure Control. We informed ATC of windshear warning and they asked our intentions. I asked about current field conditions at MIA and they stated conditions were deteriorating. We immediately informed them that we wanted to divert to RSW and declared minimum fuel. ATC offered us an immediate turn NW; however a solid line of weather presented itself and the safer course of action was to proceed SW to MTH to get around the weather before turning towards RSW. This additional vectoring as well as vectoring approaching RSW for additional divert aircraft put us significantly lower on fuel than I would have preferred. 50 NM south of RSW both low fuel alerts presented. We completed QRH procedure and opened the crossfeed valve. Cleared for approach and landing to Runway 24. Outside of the FAF; Tower cancelled our landing clearance in an attempt to place a departure in front of us. I told Tower negative; we were minimum fuel and could not accept the possibility of a go-around.  Tower held other aircraft short and recleared us to land. Fuel on touchdown was 3.2. Proceeded uneventfully to gate where we awaited fuel; dispatch release; and ground stop to MIA to be lifted.Had we not been VFR with a good ride and the airport and runway in sight for the entire downwind; base; and final I never would have attempted this approach. Being in the clear made me much more comfortable with all of the weather in the area. I wish I had asked for additional information from the previous arrival as to the windshear they had encountered. If I had; I may have abandoned the approach much earlier; possibly before we were alerted to our own windshear event.


Second narrative: Flying to MIA we encountered windshear on approach and executed the escape maneuver; during the event there was a 4 knot flap overspeed that I did not notice at the time. Due to the missed approach; the closure of MIA airport and extended vectors around thunderstorms; we were becoming concerned about fuel quantity and declared minimum fuel with ATC. Ft. Myers was the closest alternate and we proceeded there. While on final approach the Tower cancelled our landing clearance in an attempt to get another aircraft out. We rejected that cancellation and told Tower we needed to land due to fuel situation. We were prepared to declare a fuel emergency but felt it was not necessary because Tower recleared us to land.


Synopsis: B737-800 flight crew experiences a windshear alert during approach and goes around resulting in a momentary flap overspeed. With extensive vectoring before and after the approach and deteriorating weather; the crew elects to divert to their planned alternate after declaring minimum fuel.