Narrative:

I just finished callback #189 and would like to add my 2 cents to the wake turbulence fund. I currently captain an emb-120 for a commuter airline although I have a long history of being an aviation junkie including soaring, aerobatics and being an avid reader of callback since its first issue. I personally have not had any noteworthy wake encounters lately, but I would like to offer some observations that might not have made it back to the 'lab' from the 'real world': although the text books teach that vortices descend 1000 ft and then level off, I personally have flown ILS's in cavu conditions and clipped the wake of preceding aircraft that were in sight and on the same profile as me. Local topography, such as the lone hill just short of runway 32 at pit can cause a segment of a preceding aircraft's wake to penetrate the approach path (read: thump on short final). Most anyone who has seen a famous pilot perform his low level aerobatic routine up at osh in his seafury has probably noted that occasionally the smoke he trails from his wingtips will break out of the classic parallel lines of static vortices and reform into a series of warped and twisted smoke rings made up of segments of the right and left vortices that have combined. I believe it would take an atmospheric physicist or at least a meteorologist who has a grip on how jetstreams, jet cores, high and low level low pressure areas interact to accurately describe the way these phenomena twist about once they form up. Although our kinder, gentler FAA has seen the (media) light on one level of safety and has acquired a heightened awareness of wake turbulence and its effects, there is one glaring oversight I would like to address: sequencing of faster and slower aircraft. In the simple case of a string of aircraft arriving at one altitude, the interval between the aircraft allows 1 wake to descend out of the way before another aircraft comes along. The common practice at pit has us slower folk at a lower altitude than the faster folk. Since we all fly the same path once inside the feeder fix, their wake is going to make it to my level, although there will usually be some xtrack drift of the wake. The real kicker is that the altitude difference is frequently maintained until glide slope intercept. This, of course, means that we have to intercept the faster (read heavier) aircraft's path from beneath. Perhaps I'm missing something, but that just doesn't seem very bright. Especially considering the significant number of times I find myself behind an airline 757.

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Original NASA ASRS Text

Title: WAKE TURB.

Narrative: I JUST FINISHED CALLBACK #189 AND WOULD LIKE TO ADD MY 2 CENTS TO THE WAKE TURB FUND. I CURRENTLY CAPT AN EMB-120 FOR A COMMUTER AIRLINE ALTHOUGH I HAVE A LONG HISTORY OF BEING AN AVIATION JUNKIE INCLUDING SOARING, AEROBATICS AND BEING AN AVID READER OF CALLBACK SINCE ITS FIRST ISSUE. I PERSONALLY HAVE NOT HAD ANY NOTEWORTHY WAKE ENCOUNTERS LATELY, BUT I WOULD LIKE TO OFFER SOME OBSERVATIONS THAT MIGHT NOT HAVE MADE IT BACK TO THE 'LAB' FROM THE 'REAL WORLD': ALTHOUGH THE TEXT BOOKS TEACH THAT VORTICES DSND 1000 FT AND THEN LEVEL OFF, I PERSONALLY HAVE FLOWN ILS'S IN CAVU CONDITIONS AND CLIPPED THE WAKE OF PRECEDING ACFT THAT WERE IN SIGHT AND ON THE SAME PROFILE AS ME. LOCAL TOPOGRAPHY, SUCH AS THE LONE HILL JUST SHORT OF RWY 32 AT PIT CAN CAUSE A SEGMENT OF A PRECEDING ACFT'S WAKE TO PENETRATE THE APCH PATH (READ: THUMP ON SHORT FINAL). MOST ANYONE WHO HAS SEEN A FAMOUS PLT PERFORM HIS LOW LEVEL AEROBATIC ROUTINE UP AT OSH IN HIS SEAFURY HAS PROBABLY NOTED THAT OCCASIONALLY THE SMOKE HE TRAILS FROM HIS WINGTIPS WILL BREAK OUT OF THE CLASSIC PARALLEL LINES OF STATIC VORTICES AND REFORM INTO A SERIES OF WARPED AND TWISTED SMOKE RINGS MADE UP OF SEGMENTS OF THE R AND L VORTICES THAT HAVE COMBINED. I BELIEVE IT WOULD TAKE AN ATMOSPHERIC PHYSICIST OR AT LEAST A METEOROLOGIST WHO HAS A GRIP ON HOW JETSTREAMS, JET CORES, HIGH AND LOW LEVEL LOW PRESSURE AREAS INTERACT TO ACCURATELY DESCRIBE THE WAY THESE PHENOMENA TWIST ABOUT ONCE THEY FORM UP. ALTHOUGH OUR KINDER, GENTLER FAA HAS SEEN THE (MEDIA) LIGHT ON ONE LEVEL OF SAFETY AND HAS ACQUIRED A HEIGHTENED AWARENESS OF WAKE TURB AND ITS EFFECTS, THERE IS ONE GLARING OVERSIGHT I WOULD LIKE TO ADDRESS: SEQUENCING OF FASTER AND SLOWER ACFT. IN THE SIMPLE CASE OF A STRING OF ACFT ARRIVING AT ONE ALT, THE INTERVAL BTWN THE ACFT ALLOWS 1 WAKE TO DSND OUT OF THE WAY BEFORE ANOTHER ACFT COMES ALONG. THE COMMON PRACTICE AT PIT HAS US SLOWER FOLK AT A LOWER ALT THAN THE FASTER FOLK. SINCE WE ALL FLY THE SAME PATH ONCE INSIDE THE FEEDER FIX, THEIR WAKE IS GOING TO MAKE IT TO MY LEVEL, ALTHOUGH THERE WILL USUALLY BE SOME XTRACK DRIFT OF THE WAKE. THE REAL KICKER IS THAT THE ALT DIFFERENCE IS FREQUENTLY MAINTAINED UNTIL GLIDE SLOPE INTERCEPT. THIS, OF COURSE, MEANS THAT WE HAVE TO INTERCEPT THE FASTER (READ HEAVIER) ACFT'S PATH FROM BENEATH. PERHAPS I'M MISSING SOMETHING, BUT THAT JUST DOESN'T SEEM VERY BRIGHT. ESPECIALLY CONSIDERING THE SIGNIFICANT NUMBER OF TIMES I FIND MYSELF BEHIND AN AIRLINE 757.

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.