Narrative:

We were operating with a deferred right engine anti-ice system which restricted us to 11 degrees and above in clouds to comply. Because of this we could not fly very high; 10 thousand max with forecast; and couldn't go too low because of the mountainous terrain between the two cities. About 35 minutes from atl; we started seeing some buildups on the radar. We were in almost 100% IMC on this flight with occasional glimpses of towering cumulous; but nothing worth worrying too much about. We did start veering left about 30-40 degrees (under approach's approval) to stay out of the more defined radar returns; but at this point they were isolated and easily avoidable. I picked up the weather at atl: 290@11 gusting 16; 10miles visibility; few@2000; 3000 scattered temp27/23 altimeter 30.07. They were using prm approaches but this seemed more for traffic accommodation rather than weather. I heard no announcement of any impending weather at the atl airport. We were cleared for the prm 27L approach 'fly 240 until established' and were at 7000 feet and capturing. As the autopilot turned to lock in on the localizer and glide slope it slowly corrected to the final approach course. As the heading stabilized; the radar came to life with a red area straight ahead. I've seen similar at close range zoom but it was a surprise to see it 'out of the blue' like this. We continued and contacted tower. Tower cleared us to land and reported a +/-15 knot airspeed by a 737. Then at 5000 feet; we had immediate extreme turbulence. Wings rolled 30 degrees left; and left and right yaw like I've never felt before. The airspeed went from 180 to 220 in 2 seconds and then back to 160 so +40 and -20 respectively. All of us agreed that a go around was the best option. We were still at 5000 and advanced power; and hit GA buttons to get at least a nose high pitch. We continued straight ahead and I told tower we were going around. From that point we climbed to 5800 whether in updraft or do to the addition of power I don't know. We were not assigned an altitude yet but just cleared to land. Then tower (or prm monitor) said maintain 5000 and track localizer outbound. We descended at 500 fpm or so and were still getting good turbulence and I was flustered at how things were going. I said 'we need a vector out of this stuff.' then the tower/prm frequencies started to mix a little. Tower was still talking to other aircraft and the prm guy (who should override) was not completely coming through. We were; however; able to receive the majority of his transmissions and eventually turned left twice for a left downwind for prm runway 28. We both agreed that our last turbulence might have been a small pocket or anomaly and that one more try was worth a shot. We briefed and were turned base; heading 360. On base; we saw that same red blob of weather. I asked the first officer what he thought and he was ok with it. Right then we got 'turn left 330 cleared prm 28.' I took one last look at that red blob and made a split second decision that I was indeed not good with another attempt into that and spun the heading wheel right to 090 and told approach were out of there. I just had a bad feeling about that radar return especially in light of the last approach attempt. Heading east; we broke into the clear; climbed to 8000 and started to divert. Once level and re-grouped I called dispatch about a possible diversion. Dispatch said there was bad weather between our present position and our alternate. We then discussed a return back atl. He said the weather had now moved off the airport. I agreed that we could head back towards atl for one more try. We established a bingo fuel number. If we got to atl and again had issues we would divert. I updated the passengers. I did another descent check: wind 310@8; 10 miles; light rain; few 2000 ts east moving east. Sounded better than what we flew through and out the window looked like the anvil tops had sheared off the original storms; butthey were still in the area. Only a few smalls cells; isolated and we were one of the only planes in the area it seemed. We flew through light turbulence and then broke out to what seemed like a different world; clear skies; clam wind and sunny atl terminal area. The landing was a greaser by the first officer. Most of my concern lies with the weather that was sitting over the atl airport. We were not advised of the extreme precipitation and only saw it when it was too late to do anything about it but go around and fly through it. Had I known; I might have gone into holding or gotten a route to the backside and waited it out to the west. One variable was our low altitude restriction which made the onboard radar less effective. It seemed that at our altitude; 35-40 miles was the limit of accurate returns; at that range we were able to avoid the little weather we encountered north of atl.

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Original NASA ASRS Text

Title: Air Carrier small turboprop Captain reports encountering severe turbulence during approach to ATL and missed approach. The decision to divert is made then rescinded as enroute weather to alternate goes down and ATL weather improves. Uneventful landing ensues.

Narrative: We were operating with a deferred right engine anti-ice system which restricted us to 11 degrees and above in clouds to comply. Because of this we could not fly very high; 10 thousand max with forecast; and couldn't go too low because of the mountainous terrain between the two cities. About 35 minutes from ATL; we started seeing some buildups on the radar. We were in almost 100% IMC on this flight with occasional glimpses of towering cumulous; but nothing worth worrying too much about. We did start veering left about 30-40 degrees (under Approach's approval) to stay out of the more defined radar returns; but at this point they were isolated and easily avoidable. I picked up the weather at ATL: 290@11 gusting 16; 10miles visibility; few@2000; 3000 scattered temp27/23 altimeter 30.07. They were using PRM approaches but this seemed more for traffic accommodation rather than weather. I heard no announcement of any impending weather at the ATL airport. We were cleared for the PRM 27L approach 'fly 240 until established' and were at 7000 feet and capturing. As the autopilot turned to lock in on the localizer and glide slope it slowly corrected to the final approach course. As the heading stabilized; the radar came to life with a red area straight ahead. I've seen similar at close range zoom but it was a surprise to see it 'out of the blue' like this. We continued and contacted Tower. Tower cleared us to land and reported a +/-15 knot airspeed by a 737. Then at 5000 feet; we had immediate extreme turbulence. Wings rolled 30 degrees left; and left and right yaw like I've never felt before. The airspeed went from 180 to 220 in 2 seconds and then back to 160 so +40 and -20 respectively. All of us agreed that a go around was the best option. We were still at 5000 and advanced power; and hit GA buttons to get at least a nose high pitch. We continued straight ahead and I told Tower we were going around. From that point we climbed to 5800 whether in updraft or do to the addition of power I don't know. We were not assigned an altitude yet but just cleared to land. Then Tower (or PRM monitor) said maintain 5000 and track localizer outbound. We descended at 500 fpm or so and were still getting good turbulence and I was flustered at how things were going. I said 'we need a vector out of this stuff.' Then the Tower/PRM frequencies started to mix a little. Tower was still talking to other aircraft and the PRM guy (who should override) was not completely coming through. We were; however; able to receive the majority of his transmissions and eventually turned left twice for a left downwind for PRM RWY 28. We both agreed that our last turbulence might have been a small pocket or anomaly and that one more try was worth a shot. We briefed and were turned base; heading 360. On base; we saw that same red blob of weather. I asked the First Officer what he thought and he was ok with it. Right then we got 'turn left 330 cleared PRM 28.' I took one last look at that Red blob and made a split second decision that I was indeed not good with another attempt into that and spun the heading wheel right to 090 and told Approach were out of there. I just had a bad feeling about that radar return especially in light of the last approach attempt. Heading east; we broke into the clear; climbed to 8000 and started to divert. Once level and re-grouped I called Dispatch about a possible diversion. Dispatch said there was bad weather between our present position and our alternate. We then discussed a return back ATL. He said the weather had now moved off the airport. I agreed that we could head back towards ATL for one more try. We established a bingo fuel number. If we got to ATL and again had issues we would divert. I updated the passengers. I did another descent check: wind 310@8; 10 miles; light rain; few 2000 TS E moving E. Sounded better than what we flew through and out the window looked like the anvil tops had sheared off the original storms; butthey were still in the area. Only a few smalls cells; isolated and we were one of the only planes in the area it seemed. We flew through light turbulence and then broke out to what seemed like a different world; clear skies; clam wind and sunny ATL terminal area. The landing was a greaser by the First Officer. Most of my concern lies with the weather that was sitting over the ATL airport. We were not advised of the extreme precipitation and only saw it when it was too late to do anything about it but go around and fly through it. Had I known; I might have gone into holding or gotten a route to the backside and waited it out to the west. One variable was our low altitude restriction which made the onboard radar less effective. It seemed that at our altitude; 35-40 miles was the limit of accurate returns; at that range we were able to avoid the little weather we encountered north of ATL.

Data retrieved from NASA's ASRS site as of April 2012 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.