B737-800
Flight Crew Air Transport Pilot (ATP)
Fatigue; Confusion
Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
General None Reported / Taken
Human Factors; Weather
Flight was uneventful until in the terminal area. While on the localizer; on board radar showed large weather cell immediately to the south of [the airport.] Visually; both the First Officer and I could see shafts of rain coming down just a few miles south of the airfield but there was no rain in our path to the runway and we had a clear view to the airport. Shortly after [inbound fix] Tower issued a microburst alert for our runway; indicating a 35 KT loss at 2 mile final. I was the pilot flying and I elected to continue the approach. We landed uneventfully. The approach was stable throughout. After further consideration of the event after the fact; my decision to continue the approach was contrary to [company] guidance. At the time of the alert; my First Officer recommended a go-around. Several factors influenced my decision to continue. I realize now that guidance is unequivocal in such a circumstance; and I offer these thoughts to describe how I came to my erroneous conclusion. First of all; the flight was an all-nighter. At the time the alert was issued; it was approximately XA:45 am body clock time. Certainly; fatigue was a factor which clouded my thought process.  Secondly; this is the first time in my 22 year career that I've encountered a microburst alert based on a TDWR or LLWAS-NE system. My initial thought at the time was that it was a report from a preceding aircraft; not these ground-based systems. Since we knew we were not following anyone on final; the thought that this was stale information crossed my mind. Also; we had a clear; unobstructed view of the landing runway; saw no rain in our path; and noted the weather was close but to the south of our path and the airport. I did consider the possibility of a dry microburst; but again considered the information might be stale and elected to proceed with caution; intending to go-around at the first sign of a loss of airspeed. Incidentally; we did brief an escape plan -- to the north -- at about 10-15 mile final as we approached the airport due to the weather visible to the south. Also; I erroneously understood the phrase microburst alert to be advisory rather than directive. Lastly; windshear and microburst training at [my airline] emphasizes cues from aircraft performance and on board warning systems. If the scenario we encountered was ever discussed in my training; I don't recall. But I will not forget this event and the lesson learned. I discussed the situation with my First Officer briefly after landing and at length on the flight home. In the lengthy discussion we agreed that my decision was incorrect and talked about the contributing factors mentioned above. In that further discussion; one human-factors-type consideration occurred to us related to the terminology of the ground based reporting systems described in [our operations manual]. Windshear/Microburst Guidance policies for operating with Windshear/Microburst Alerts and Advisories in effect. Refer to QRH Maneuvers Section for additional guidance. A.) Windshear Alert or Advisories. Takeoff and landing is permitted; however caution should be exercised. B.) Microburst Alert. Flights may not takeoff or conduct the final approach segment to a runway when ATC is reporting a runway specific microburst alert. If established on the final approach segment of an approach and ATC issues a microburst alert for the runway of intended landing; a go-around must be executed; and if necessary; accomplish wind-shear escape procedures. C.) Microburst Advisories. If the statement: 'Microburst Advisories in effect' is broadcast on the ATIS or issued by ATC; takeoff and landing is permitted; however caution should be exercised. Suggestions: Considering this was the first time either I or the First Officer had encountered such a microburst alert; I erroneously deemed the term 'alert' to be advisory; not directive. Of the three cases listed above; A and C allow continuation with caution and B does not. In the heat of battle; or the fog of fatigue; I'd suggest that the terms 'alert' and 'advisory' are too easily confused. I'd further suggest that 'microburst warning' would be a better term to identify the urgency; the directive nature and ground-based source of this actually and currently detected microburst information. Having grown up in tornado country; I know that a tornado warning means a tornado has been detected and is actually present. The same mental association to inform an aircrew of a detected microburst would avoid a mental A-word debate (Was that an Alert? Advisory? What's the difference again?). Elsewhere in our training; W-words are action words: WINDSHEAR; ground proximity WARNING. A warning always identifies a present threat. An alert may be advisory or directive. Understanding that such a change in terminology would require FAA involvement; a more immediate means of addressing a potentially wide-spread confusion/problem would be to incorporate such ground- based microburst alerts in recurrent training; emphasizing that in this case the alert is directive. This is one of those things that you don't do twice; but it would be prudent to ensure that all crews on all fleets have their 'once' experience in a training environment rather than an operational one.
Windshear [and] microburst simulator training should include a scenario where ATC voices various windshear or microburst Advisories or Alerts in order for crews to differentiate what appropriate actions to undertake. We train satisfactorily in the simulator to employ procedures when a windshear event is physically or aurally detected in progress but can easily; in real world operations; be lured into a false sense of security when ATC issues alerts and the meteorological environment continues to remain very stable. In the future if ATC issues a Microburst 'Alert' I will emphasize a mandatory go-around is executed.
B737-800 flight crew reported they received a microburst alert from Tower on final approach and the Captain elected to continue the approach contrary to company guidelines and First Officer recommendation.