Narrative:

About 7 to 8 mi in trail of a B-757 received a strong jolt of moderate turbulence at 9000 ft, lasting less than 2 seconds. Was unable to get a word in to ATC to advise and received a second slightly lesser jolt at about 6500 ft during descent on downwind for runway 27L at ord. ATC was advised as we turned base leg. Separation of 7-8 mi remained with no other occurrences. No injuries were sustained. Callback conversation with reporter revealed the following: the reporter stated the primary cause of the problem was inadequate spacing in calm air behind the 757. He said there was nothing he did that he would have done differently were the situation to occur again. In his case, the controller did not advise him he was following a B757. He says he wishes the controller would have told him there was 757 ahead he would be following for the approach. He hit the 757 wake twice.

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Original NASA ASRS Text

Title: F-100 WAKE TURB VORTEX ENCOUNTER BEHIND A B757.

Narrative: ABOUT 7 TO 8 MI IN TRAIL OF A B-757 RECEIVED A STRONG JOLT OF MODERATE TURB AT 9000 FT, LASTING LESS THAN 2 SECONDS. WAS UNABLE TO GET A WORD IN TO ATC TO ADVISE AND RECEIVED A SECOND SLIGHTLY LESSER JOLT AT ABOUT 6500 FT DURING DSCNT ON DOWNWIND FOR RWY 27L AT ORD. ATC WAS ADVISED AS WE TURNED BASE LEG. SEPARATION OF 7-8 MI REMAINED WITH NO OTHER OCCURRENCES. NO INJURIES WERE SUSTAINED. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: THE RPTR STATED THE PRIMARY CAUSE OF THE PROB WAS INADEQUATE SPACING IN CALM AIR BEHIND THE 757. HE SAID THERE WAS NOTHING HE DID THAT HE WOULD HAVE DONE DIFFERENTLY WERE THE SIT TO OCCUR AGAIN. IN HIS CASE, THE CTLR DID NOT ADVISE HIM HE WAS FOLLOWING A B757. HE SAYS HE WISHES THE CTLR WOULD HAVE TOLD HIM THERE WAS 757 AHEAD HE WOULD BE FOLLOWING FOR THE APCH. HE HIT THE 757 WAKE TWICE.

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.