Wake encounter. - NASA ASRS

Attributes
ACN	295124
Time
Date	199501
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : bos
State Reference	MA
Altitude	msl bound lower : 5600 msl bound upper : 5600
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bos
Operator	common carrier : air taxi
Make Model Name	Learjet 35
Operating Under FAR Part	Part 135
Flight Phase	descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 145 flight time total : 7000 flight time type : 2200
ASRS Report	295124
Person 2
Affiliation	Other
Qualification	pilot : atp
Events
Anomaly	inflight encounter other
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other

Narrative:

Our flight was being vectored to the ILS runway 4R behind a B757. While descending through 5600 ft MSL we encountered the wake turbulence. I immediately disconnected the autoplt and arrested the rolling moment. This encounter was brief and mild compared to some in the past. Still a problem that needs to be addressed. The issuing of wake turbulence advisories doesn't solve the safety problem. We received several advisories from approach and tower, which tied up valuable radio time, but didn't help us avoid the wake. As it was, we only saw the B-757 briefly while being vectored for the approach. Callback conversation with reporter revealed the following information: the reporter says that the flight crew anticipated the major rolling moment because they felt a few nibbles before it hit. So they disconnected the autoplt just as they started to roll and were able to keep it to about 10 degrees left bank and a 10 degree left heading change. This is the reporter's second wake turbulence report and though this was milder he is just as strongly convinced that the advisories are of limited value. Spacing in- trail and altitude separation, with the hvys being lower is something we should be doing according to the reporter.

Original NASA ASRS Text

Title: WAKE ENCOUNTER.

Narrative: OUR FLT WAS BEING VECTORED TO THE ILS RWY 4R BEHIND A B757. WHILE DSNDING THROUGH 5600 FT MSL WE ENCOUNTERED THE WAKE TURB. I IMMEDIATELY DISCONNECTED THE AUTOPLT AND ARRESTED THE ROLLING MOMENT. THIS ENCOUNTER WAS BRIEF AND MILD COMPARED TO SOME IN THE PAST. STILL A PROB THAT NEEDS TO BE ADDRESSED. THE ISSUING OF WAKE TURB ADVISORIES DOESN'T SOLVE THE SAFETY PROB. WE RECEIVED SEVERAL ADVISORIES FROM APCH AND TWR, WHICH TIED UP VALUABLE RADIO TIME, BUT DIDN'T HELP US AVOID THE WAKE. AS IT WAS, WE ONLY SAW THE B-757 BRIEFLY WHILE BEING VECTORED FOR THE APCH. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR SAYS THAT THE FLC ANTICIPATED THE MAJOR ROLLING MOMENT BECAUSE THEY FELT A FEW NIBBLES BEFORE IT HIT. SO THEY DISCONNECTED THE AUTOPLT JUST AS THEY STARTED TO ROLL AND WERE ABLE TO KEEP IT TO ABOUT 10 DEGS L BANK AND A 10 DEG L HDG CHANGE. THIS IS THE RPTR'S SECOND WAKE TURB RPT AND THOUGH THIS WAS MILDER HE IS JUST AS STRONGLY CONVINCED THAT THE ADVISORIES ARE OF LIMITED VALUE. SPACING IN- TRAIL AND ALT SEPARATION, WITH THE HVYS BEING LOWER IS SOMETHING WE SHOULD BE DOING ACCORDING TO THE RPTR.

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.