Narrative:

We had been cleared for an ILS to 27L in atl. We joined the final at 3500 ft and, as the GS started to move, we got hit by wake turbulence that banked the aircraft about 45 degrees to the right. We recovered and continued. We asked approach for the type of aircraft we were following. He stated that we were 3 1/2 mi behind an large transport. We intercepted the GS and got hit again by wake turbulence although not as bad. We had the airport in sight and decided to stay above the GS to avoid the wake. We were about 1 1/2 dots high, above the GS when we hit extreme wake turbulence, the aircraft violently rolled into a 90 degree bank to the right, pitched 10 to 12 degrees down, and the IAS went to zero in less than 5 seconds. It took between 130-140 percent torque to recover and start flying again. We initiated a go around and advised the tower. We returned for a normal landing. After landing, we learned from another company pilot that, before we switched to the tower frequency, the large transport had reported to the tower that he was full deflection above the GS because of wake turbulence from a widebody transport. The tower cleared the large transport for a visual approach after the large transport said he saw the airport. The large transport made a quick descent and landed. Because of this, our normal procedure of staying above the GS to stay out of harm's way did not work. The tower should have told us that the large transport went high. I would have abandoned the approach. In atl, we follow many different types of large aircraft and the large transport has the worst wake turbulence. I think that the large transport should be classified as a heavy so we could get heavy separation. 3 mi behind an large transport is too close.

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Original NASA ASRS Text

Title: AN LTT ACR HAD AN ENCOUNTER WITH SEVERE WAKE TURB REQUIRING A GAR.

Narrative: WE HAD BEEN CLRED FOR AN ILS TO 27L IN ATL. WE JOINED THE FINAL AT 3500 FT AND, AS THE GS STARTED TO MOVE, WE GOT HIT BY WAKE TURB THAT BANKED THE ACFT ABOUT 45 DEGS TO THE R. WE RECOVERED AND CONTINUED. WE ASKED APCH FOR THE TYPE OF ACFT WE WERE FOLLOWING. HE STATED THAT WE WERE 3 1/2 MI BEHIND AN LGT. WE INTERCEPTED THE GS AND GOT HIT AGAIN BY WAKE TURB ALTHOUGH NOT AS BAD. WE HAD THE ARPT IN SIGHT AND DECIDED TO STAY ABOVE THE GS TO AVOID THE WAKE. WE WERE ABOUT 1 1/2 DOTS HIGH, ABOVE THE GS WHEN WE HIT EXTREME WAKE TURB, THE ACFT VIOLENTLY ROLLED INTO A 90 DEG BANK TO THE R, PITCHED 10 TO 12 DEGS DOWN, AND THE IAS WENT TO ZERO IN LESS THAN 5 SECONDS. IT TOOK BTWN 130-140 PERCENT TORQUE TO RECOVER AND START FLYING AGAIN. WE INITIATED A GAR AND ADVISED THE TWR. WE RETURNED FOR A NORMAL LNDG. AFTER LNDG, WE LEARNED FROM ANOTHER COMPANY PLT THAT, BEFORE WE SWITCHED TO THE TWR FREQ, THE LGT HAD RPTED TO THE TWR THAT HE WAS FULL DEFLECTION ABOVE THE GS BECAUSE OF WAKE TURB FROM A WDB. THE TWR CLRED THE LGT FOR A VISUAL APCH AFTER THE LGT SAID HE SAW THE ARPT. THE LGT MADE A QUICK DSCNT AND LANDED. BECAUSE OF THIS, OUR NORMAL PROC OF STAYING ABOVE THE GS TO STAY OUT OF HARM'S WAY DID NOT WORK. THE TWR SHOULD HAVE TOLD US THAT THE LGT WENT HIGH. I WOULD HAVE ABANDONED THE APCH. IN ATL, WE FOLLOW MANY DIFFERENT TYPES OF LARGE ACFT AND THE LGT HAS THE WORST WAKE TURB. I THINK THAT THE LGT SHOULD BE CLASSIFIED AS A HEAVY SO WE COULD GET HVY SEPARATION. 3 MI BEHIND AN LGT IS TOO CLOSE.

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.