Narrative:

During departure from phl, aircraft was at 10000 ft level flight -- clear, smooth air. Aircraft was cleared to 14000 ft and flying PIC in right seat initiated climb. Passing 10600 ft aircraft began to experience some turbulence, then, within 2 seconds, began an uncommanded left roll. PIC countered roll, but within 2 more seconds, roll rate/turbulence increased. PIC was unable to counter roll with full right aileron deflection. Climb rate diminished to zero with 8-10 degrees nose-up pitch. As roll approached 35-40 degrees, PIC reduced power, lowered nose, and as aircraft descended below 10000 ft, lateral control was regained. Heading remained fairly constant, and level flight was obtained at approximately 9500 ft. Crew queried phl departure control and was told that aircraft was approximately 12 NM behind a departing B757. A reduced rate of climb was utilized until ATC reported divergent flight paths between B757 and incident aircraft. 12 mi in-trail spacing would appear to be sufficient, but in this case was not. Contributing factor may have been 35 KT tailwind in area. Of note, despite fact that passenger seat belt was still illuminated, a passenger was out of his seat and momentarily lost his balance, with no injuries. Callback conversation with reporter revealed the following information: reporter states that whenever he is lined up after a heavier aircraft has departed he starts his clock to assure enough time prior to his departure to avoid wake turbulence. He had the required 3 mins behind the B757 and never expected to have a problem. When the controller indicated the B757 was 12 mi ahead he was quite surprised to have experienced the wake turbulence. When the roll upset occurred the rate of roll was not severe or rapid, more like entering a normal turn. However, he could not control the turn until he started the descent and removed himself from the area of the wake rotation. He descended about 800 FPM and the incident was over within 30 seconds. Reporter remembers contacting ATC and receiving no response. He received no other advisories. Reporter has tried to convince his company to install TCASII on the aircraft and feels he would have a better awareness of the in trail distance. Recently he was flying and sighted a B757 overhead and the light was such that one could see the contrails in rotation. It was the classic example that one sees in test films of wake turbulence. Reporter feels this wake turbulence is peculiar to the B757 wing, but does not know why.

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Original NASA ASRS Text

Title: CITATION 5 FLC RPT OF WAKE TURB ENCOUNTER FOLLOWING A B757 ON CLBOUT FROM PHL. EXTREME ROLL OF 35-40 DEGS AND INABILITY TO CONTINUE CLB OR HOLD ALT RESULTED. RPTR DSNDED AND TURNED A FEW DEGS OFF COURSE UNTIL GAINING CTL AGAIN. CTLR INDICATED ACFT WERE ABOUT 12 MI APART.

Narrative: DURING DEP FROM PHL, ACFT WAS AT 10000 FT LEVEL FLT -- CLR, SMOOTH AIR. ACFT WAS CLRED TO 14000 FT AND FLYING PIC IN R SEAT INITIATED CLB. PASSING 10600 FT ACFT BEGAN TO EXPERIENCE SOME TURB, THEN, WITHIN 2 SECONDS, BEGAN AN UNCOMMANDED L ROLL. PIC COUNTERED ROLL, BUT WITHIN 2 MORE SECONDS, ROLL RATE/TURB INCREASED. PIC WAS UNABLE TO COUNTER ROLL WITH FULL R AILERON DEFLECTION. CLB RATE DIMINISHED TO ZERO WITH 8-10 DEGS NOSE-UP PITCH. AS ROLL APCHED 35-40 DEGS, PIC REDUCED PWR, LOWERED NOSE, AND AS ACFT DSNDED BELOW 10000 FT, LATERAL CTL WAS REGAINED. HDG REMAINED FAIRLY CONSTANT, AND LEVEL FLT WAS OBTAINED AT APPROX 9500 FT. CREW QUERIED PHL DEP CTL AND WAS TOLD THAT ACFT WAS APPROX 12 NM BEHIND A DEPARTING B757. A REDUCED RATE OF CLB WAS UTILIZED UNTIL ATC RPTED DIVERGENT FLT PATHS BTWN B757 AND INCIDENT ACFT. 12 MI IN-TRAIL SPACING WOULD APPEAR TO BE SUFFICIENT, BUT IN THIS CASE WAS NOT. CONTRIBUTING FACTOR MAY HAVE BEEN 35 KT TAILWIND IN AREA. OF NOTE, DESPITE FACT THAT PAX SEAT BELT WAS STILL ILLUMINATED, A PAX WAS OUT OF HIS SEAT AND MOMENTARILY LOST HIS BAL, WITH NO INJURIES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT WHENEVER HE IS LINED UP AFTER A HEAVIER ACFT HAS DEPARTED HE STARTS HIS CLOCK TO ASSURE ENOUGH TIME PRIOR TO HIS DEP TO AVOID WAKE TURB. HE HAD THE REQUIRED 3 MINS BEHIND THE B757 AND NEVER EXPECTED TO HAVE A PROB. WHEN THE CTLR INDICATED THE B757 WAS 12 MI AHEAD HE WAS QUITE SURPRISED TO HAVE EXPERIENCED THE WAKE TURB. WHEN THE ROLL UPSET OCCURRED THE RATE OF ROLL WAS NOT SEVERE OR RAPID, MORE LIKE ENTERING A NORMAL TURN. HOWEVER, HE COULD NOT CTL THE TURN UNTIL HE STARTED THE DSCNT AND REMOVED HIMSELF FROM THE AREA OF THE WAKE ROTATION. HE DSNDED ABOUT 800 FPM AND THE INCIDENT WAS OVER WITHIN 30 SECONDS. RPTR REMEMBERS CONTACTING ATC AND RECEIVING NO RESPONSE. HE RECEIVED NO OTHER ADVISORIES. RPTR HAS TRIED TO CONVINCE HIS COMPANY TO INSTALL TCASII ON THE ACFT AND FEELS HE WOULD HAVE A BETTER AWARENESS OF THE IN TRAIL DISTANCE. RECENTLY HE WAS FLYING AND SIGHTED A B757 OVERHEAD AND THE LIGHT WAS SUCH THAT ONE COULD SEE THE CONTRAILS IN ROTATION. IT WAS THE CLASSIC EXAMPLE THAT ONE SEES IN TEST FILMS OF WAKE TURB. RPTR FEELS THIS WAKE TURB IS PECULIAR TO THE B757 WING, BUT DOES NOT KNOW WHY.

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.