Flight Crew Last 90 Days 218; Flight Crew Type 12500
Time Pressure; Human-Machine Interface; Distraction
Aircraft Equipment Problem Less Severe
General None Reported / Taken
Aircraft; Airport
At 500 FT AGL on final to Runway 12L in STL; we received a PWS warning (GO AROUND...WINDSHEAR AHEAD). The weather at the time was partly cloudy with no convective activity in the area. Approximately five seconds after receiving the PWS warning; the weather radar went into test mode. The pilot not flying and I briefly discussed the situation and I made the decision to land with no objection from the pilot not flying. After parking at the gate; I called for the Maintenance person at STL and described to him what had happened. He stated that this was a common occurrence at STL and there was nothing wrong with the aircraft so no logbook entry was made. The Maintenance person stated this was a known problem and 'they' (I don't know who 'they' are) recently flew an aircraft around STL to try and isolate the cause of the erroneous PWS warnings; but were unable to find the cause.
The reporter stated that he has not personally seen or heard of this type anomaly occurring before it happened on this flight. The PWS warning symbol identifying the supposed weather event was at the aircraft's eleven o'clock about five miles. The reporter did not see anything which would cause that warning to activate.
At 500 AGL on final approach; we got a windshear go-around warning. There was no convective activity in the area and no windshear warning. The Captain and I talked about it and he elected to continue the approach and landing without incident. Five seconds after the initial warning; the radar went into test mode automatically. After the landing; the Captain contacted STL Maintenance to check out the radar and he was told that erroneous windshear warning has happened multiple times before.
A B737-700 flight crew reported an EGPWS Predictive Windshear Warning (PWS) while on short final for STL Runway 12L; but because daylight VMC conditions existed without convective activity; the approach was continued.