Narrative:

Upon arrival in the atl terminal area, we encountered heavy arrival traffic, a nearly saturated ATC environment and a number of developing cumulo nimbus cells. The largest cell appeared directly over the airport. Unknown to us, departures had been terminated due to windshear reports on departure. However, neither arrival ATIS nor ATC made no mention of this fact and approachs continued. We received the first of several (5 in all) windshear and microburst alerts while being vectored on radar downwind, indicating airspeed losses of 35 KTS. Those microburst alerts are computer generated company-transmitted warnings from our company's meteorology department, delivered via our cockpit ACARS. We elected to delay our arrival until the expiration of the microbursts. Alert valid time, approximately 15 mins. This action puzzled ATC who asked we contact them later about this, as aircraft were still arriving and no reports of windshear on approach, yet we refused to continue. Within mins, an aircraft went around from the approach reporting a 35 KT loss on final while others were then broken off the approach. Within several mins more, the cell moved off the approach path and arrs resumed uneventfully, including ours. In discussion with the approach control supervision afterwards, he felt we delayed unnecessarily and we could have beat the storm to the arrival and not complicated his airspace by refusing to begin the approach till later. In order to follow that plan of action, we would have had to systematically disregard the information we received in no less than 5 windshear and microburst reports received and the written policy in our company fom. I feel these tdwr, computer-monitored and generated alerts for windshears and microbursts are very effective in a highly dynamic WX event like we experienced. Unfortunately, this system apparently generates such a number of false reports, ATC and others regularly disregard them until an actual reported event occurs. Of course, the only down side of enhancing their airport capacity issues through measures like this is the potential of reliving great low points in aviation history -- effectively setting progress back 20 yrs.

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Original NASA ASRS Text

Title: B752 FLC RESPONDS TO A80 QUESTION ABOUT WX AVOIDANCE WHEN A80 THOUGHT THEY COULD LAND AHEAD OF THE WX.

Narrative: UPON ARR IN THE ATL TERMINAL AREA, WE ENCOUNTERED HVY ARR TFC, A NEARLY SATURATED ATC ENVIRONMENT AND A NUMBER OF DEVELOPING CUMULO NIMBUS CELLS. THE LARGEST CELL APPEARED DIRECTLY OVER THE ARPT. UNKNOWN TO US, DEPS HAD BEEN TERMINATED DUE TO WINDSHEAR RPTS ON DEP. HOWEVER, NEITHER ARR ATIS NOR ATC MADE NO MENTION OF THIS FACT AND APCHS CONTINUED. WE RECEIVED THE FIRST OF SEVERAL (5 IN ALL) WINDSHEAR AND MICROBURST ALERTS WHILE BEING VECTORED ON RADAR DOWNWIND, INDICATING AIRSPD LOSSES OF 35 KTS. THOSE MICROBURST ALERTS ARE COMPUTER GENERATED COMPANY-XMITTED WARNINGS FROM OUR COMPANY'S METEOROLOGY DEPT, DELIVERED VIA OUR COCKPIT ACARS. WE ELECTED TO DELAY OUR ARR UNTIL THE EXPIRATION OF THE MICROBURSTS. ALERT VALID TIME, APPROX 15 MINS. THIS ACTION PUZZLED ATC WHO ASKED WE CONTACT THEM LATER ABOUT THIS, AS ACFT WERE STILL ARRIVING AND NO RPTS OF WINDSHEAR ON APCH, YET WE REFUSED TO CONTINUE. WITHIN MINS, AN ACFT WENT AROUND FROM THE APCH RPTING A 35 KT LOSS ON FINAL WHILE OTHERS WERE THEN BROKEN OFF THE APCH. WITHIN SEVERAL MINS MORE, THE CELL MOVED OFF THE APCH PATH AND ARRS RESUMED UNEVENTFULLY, INCLUDING OURS. IN DISCUSSION WITH THE APCH CTL SUPERVISION AFTERWARDS, HE FELT WE DELAYED UNNECESSARILY AND WE COULD HAVE BEAT THE STORM TO THE ARR AND NOT COMPLICATED HIS AIRSPACE BY REFUSING TO BEGIN THE APCH TILL LATER. IN ORDER TO FOLLOW THAT PLAN OF ACTION, WE WOULD HAVE HAD TO SYSTEMATICALLY DISREGARD THE INFO WE RECEIVED IN NO LESS THAN 5 WINDSHEAR AND MICROBURST RPTS RECEIVED AND THE WRITTEN POLICY IN OUR COMPANY FOM. I FEEL THESE TDWR, COMPUTER-MONITORED AND GENERATED ALERTS FOR WINDSHEARS AND MICROBURSTS ARE VERY EFFECTIVE IN A HIGHLY DYNAMIC WX EVENT LIKE WE EXPERIENCED. UNFORTUNATELY, THIS SYS APPARENTLY GENERATES SUCH A NUMBER OF FALSE RPTS, ATC AND OTHERS REGULARLY DISREGARD THEM UNTIL AN ACTUAL RPTED EVENT OCCURS. OF COURSE, THE ONLY DOWN SIDE OF ENHANCING THEIR ARPT CAPACITY ISSUES THROUGH MEASURES LIKE THIS IS THE POTENTIAL OF RELIVING GREAT LOW POINTS IN AVIATION HISTORY -- EFFECTIVELY SETTING PROGRESS BACK 20 YRS.

Data retrieved from NASA's ASRS site as of July 2007 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.