Narrative:

We were holding at lufco intersection, #1 for approach. RVR during holding was 600-700'. There were other aircraft holding above us waiting for the visibility to improve. RVR started to come up and ATC started to give us a clearance, but stopped mid-sentence and told us to 'continue.' at this time (or anytime) no reason or change of sequence was given to us. As we continued to hold I noticed a heavy jet being vectored beneath us, but I lost sight of it on our outbnd leg portion of holding (we were holding at 11000). When we were finally given approach clearance we had to lost approximately 5000' to intercept the G/south, so we hurried on down. We were under the impression we were #1 on the approach. About 7500', I noticed ahead of us was a large aircraft. It appeared we were catching up. A few seconds later we got caught in that aircraft's wake turbulence. It was a heavy jet. We were never warned/advised that we were following that aircraft with minimum spacing or that we were closing (speed and distance). As a rule (especially at oak), we have been advised of both type and speed of aircraft we are following. If this had happened at a lower altitude there could have been serious consequences. We then stayed slightly above the G/south for the remainder of the approach. Visibility at airport was improved! Callback conversation with reporter revealed the following: reporter stated distance behind widebody transport was approximately 3-4 mi. Her aircraft rolled to approximately 90 degrees before recovered. She stated wind was calm. She had no discussion with ATC. Aircraft's airspeed at time of incident was approximately 150-160 KTS.

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Original NASA ASRS Text

Title: LTT X ENCOUNTERED WAKE TURBULENCE BEHIND WDB Y. LESS THAN STANDARD SEPARATION WAS LESS THAN 4 MILES FROM THE WDB. THIS IS LESS THAN STANDARD SEPARATION. 5 MILES IS REQUIRED.

Narrative: WE WERE HOLDING AT LUFCO INTXN, #1 FOR APCH. RVR DURING HOLDING WAS 600-700'. THERE WERE OTHER ACFT HOLDING ABOVE US WAITING FOR THE VISIBILITY TO IMPROVE. RVR STARTED TO COME UP AND ATC STARTED TO GIVE US A CLRNC, BUT STOPPED MID-SENTENCE AND TOLD US TO 'CONTINUE.' AT THIS TIME (OR ANYTIME) NO REASON OR CHANGE OF SEQUENCE WAS GIVEN TO US. AS WE CONTINUED TO HOLD I NOTICED A HVY JET BEING VECTORED BENEATH US, BUT I LOST SIGHT OF IT ON OUR OUTBND LEG PORTION OF HOLDING (WE WERE HOLDING AT 11000). WHEN WE WERE FINALLY GIVEN APCH CLRNC WE HAD TO LOST APPROX 5000' TO INTERCEPT THE G/S, SO WE HURRIED ON DOWN. WE WERE UNDER THE IMPRESSION WE WERE #1 ON THE APCH. ABOUT 7500', I NOTICED AHEAD OF US WAS A LARGE ACFT. IT APPEARED WE WERE CATCHING UP. A FEW SECS LATER WE GOT CAUGHT IN THAT ACFT'S WAKE TURB. IT WAS A HVY JET. WE WERE NEVER WARNED/ADVISED THAT WE WERE FOLLOWING THAT ACFT WITH MINIMUM SPACING OR THAT WE WERE CLOSING (SPD AND DISTANCE). AS A RULE (ESPECIALLY AT OAK), WE HAVE BEEN ADVISED OF BOTH TYPE AND SPD OF ACFT WE ARE FOLLOWING. IF THIS HAD HAPPENED AT A LOWER ALT THERE COULD HAVE BEEN SERIOUS CONSEQUENCES. WE THEN STAYED SLIGHTLY ABOVE THE G/S FOR THE REMAINDER OF THE APCH. VISIBILITY AT ARPT WAS IMPROVED! CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR STATED DISTANCE BEHIND WDB WAS APPROX 3-4 MI. HER ACFT ROLLED TO APPROX 90 DEGS BEFORE RECOVERED. SHE STATED WIND WAS CALM. SHE HAD NO DISCUSSION WITH ATC. ACFT'S AIRSPD AT TIME OF INCIDENT WAS APPROX 150-160 KTS.

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.