Narrative:

We were on base leg at 4000 ft, speed 210 KTS assigned, heading 300 degrees assigned, we were advised that we were following a foreign air carrier B747-300 and to call him insight. We called him insight and were given a 330 degree heading to intercept and told to follow him. No spacing information was given us by ATC. After establishing on the 330 degree heading, we saw the B747 was less than 5 mi ahead on our TCASII. We started slowing rapidly and ATC told us to hold 170 KTS till 5 DME. Our spacing continued to reduce despite continuing to slow. We were told to contact tower and, after checking in, were told we had minimum spacing behind the B747. Immediately thereafter, we hit his wake. Our aircraft rolled right and nosed down. The aircraft reached approximately 50 degrees right bank and 5-10 degrees nose down during recovery. Altitude was approximately 2700 ft MSL at recovery, a normal missed approach was initiated and an uneventful VFR landing made. Callback conversation with reporter revealed the following information: this reporter was flying a B737-200 and was being sequenced behind a B747-300. The approach controller kept asking if the captain saw the airport and the preceding aircraft. The controller said that the B747 was 5 mi ahead and was doing 170 KTS. The captain said that at this time he was doing about 210 KTS, as requested, and was on a square base leg. Just after the flight crew of the B737 called the B747 insight, the approach controller turned them on a dogleg to final closing the in-trail distance. They were then turned over to the tower controller. The tower controller reported that they were at minimum separation. The B737 crew had begun to slow and with the tower's advisory they slowed even further. The TCASII showed that they were only 2 1/2 - 3 mi behind the B747 and they were at 150 KTS. The B747 had been told to maintain at least 170 KTS to the OM, however its speed was much slower. At about 10 DME and 3300 ft the B737 hit the B747's wake. The B737's pitch changed from about 4-5 degrees nose up to 5-10 degrees nose down and the aircraft rolled right to about 50 degrees of bank. The captain attempted to correct the right bank with left aileron, but the aircraft did not respond. He finally took out the full left aileron deflection and, as he was doing so, he put in full left rudder to roll the wings level. He then pulled back on the elevator while applying some power to bring the nose up. The total altitude loss was 600 ft. The captain was a highly experienced aerobatic pilot who had been trained in the military. The first officer had not had aerobatic training. According to the captain the first officer said that when the aircraft would not roll wings level initially he thought that he was dead. The upset and the recovery lasted about 30 seconds.

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Original NASA ASRS Text

Title: WAKE ENCOUNTER -- ACR B737-200 HITS THE WAKE OF A B747- 300 AND IS UPSET. THE B737-200 RECOVERS AND MAKES A GAR.

Narrative: WE WERE ON BASE LEG AT 4000 FT, SPD 210 KTS ASSIGNED, HDG 300 DEGS ASSIGNED, WE WERE ADVISED THAT WE WERE FOLLOWING A FOREIGN ACR B747-300 AND TO CALL HIM INSIGHT. WE CALLED HIM INSIGHT AND WERE GIVEN A 330 DEG HDG TO INTERCEPT AND TOLD TO FOLLOW HIM. NO SPACING INFO WAS GIVEN US BY ATC. AFTER ESTABLISHING ON THE 330 DEG HDG, WE SAW THE B747 WAS LESS THAN 5 MI AHEAD ON OUR TCASII. WE STARTED SLOWING RAPIDLY AND ATC TOLD US TO HOLD 170 KTS TILL 5 DME. OUR SPACING CONTINUED TO REDUCE DESPITE CONTINUING TO SLOW. WE WERE TOLD TO CONTACT TWR AND, AFTER CHKING IN, WERE TOLD WE HAD MINIMUM SPACING BEHIND THE B747. IMMEDIATELY THEREAFTER, WE HIT HIS WAKE. OUR ACFT ROLLED R AND NOSED DOWN. THE ACFT REACHED APPROX 50 DEGS R BANK AND 5-10 DEGS NOSE DOWN DURING RECOVERY. ALT WAS APPROX 2700 FT MSL AT RECOVERY, A NORMAL MISSED APCH WAS INITIATED AND AN UNEVENTFUL VFR LNDG MADE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THIS RPTR WAS FLYING A B737-200 AND WAS BEING SEQUENCED BEHIND A B747-300. THE APCH CTLR KEPT ASKING IF THE CAPT SAW THE ARPT AND THE PRECEDING ACFT. THE CTLR SAID THAT THE B747 WAS 5 MI AHEAD AND WAS DOING 170 KTS. THE CAPT SAID THAT AT THIS TIME HE WAS DOING ABOUT 210 KTS, AS REQUESTED, AND WAS ON A SQUARE BASE LEG. JUST AFTER THE FLC OF THE B737 CALLED THE B747 INSIGHT, THE APCH CTLR TURNED THEM ON A DOGLEG TO FINAL CLOSING THE IN-TRAIL DISTANCE. THEY WERE THEN TURNED OVER TO THE TWR CTLR. THE TWR CTLR RPTED THAT THEY WERE AT MINIMUM SEPARATION. THE B737 CREW HAD BEGUN TO SLOW AND WITH THE TWR'S ADVISORY THEY SLOWED EVEN FURTHER. THE TCASII SHOWED THAT THEY WERE ONLY 2 1/2 - 3 MI BEHIND THE B747 AND THEY WERE AT 150 KTS. THE B747 HAD BEEN TOLD TO MAINTAIN AT LEAST 170 KTS TO THE OM, HOWEVER ITS SPD WAS MUCH SLOWER. AT ABOUT 10 DME AND 3300 FT THE B737 HIT THE B747'S WAKE. THE B737'S PITCH CHANGED FROM ABOUT 4-5 DEGS NOSE UP TO 5-10 DEGS NOSE DOWN AND THE ACFT ROLLED R TO ABOUT 50 DEGS OF BANK. THE CAPT ATTEMPTED TO CORRECT THE R BANK WITH L AILERON, BUT THE ACFT DID NOT RESPOND. HE FINALLY TOOK OUT THE FULL L AILERON DEFLECTION AND, AS HE WAS DOING SO, HE PUT IN FULL L RUDDER TO ROLL THE WINGS LEVEL. HE THEN PULLED BACK ON THE ELEVATOR WHILE APPLYING SOME PWR TO BRING THE NOSE UP. THE TOTAL ALT LOSS WAS 600 FT. THE CAPT WAS A HIGHLY EXPERIENCED AEROBATIC PLT WHO HAD BEEN TRAINED IN THE MIL. THE FO HAD NOT HAD AEROBATIC TRAINING. ACCORDING TO THE CAPT THE FO SAID THAT WHEN THE ACFT WOULD NOT ROLL WINGS LEVEL INITIALLY HE THOUGHT THAT HE WAS DEAD. THE UPSET AND THE RECOVERY LASTED ABOUT 30 SECONDS.

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.