Narrative:

After taking off of runway 17R at dfw and passing 1200 ft MSL our medium large transport encountered severe wake turbulence created by a previously departing large transport. The PF was struggling to retain aircraft control, using full flight control inputs to counteract the roll rate. The wake turbulence had changed the aircraft's heading to approximately 155 degree from the assigned 170 degree runway heading. As the PNF I told departure control that we were encountering severe wake turbulence and turning left now to get out of it. Departure control responded 'negative on the turn.' I reinformed departure that we had no choice to which they instructed that our turn must be limited to no more than 10 degree. Still in the wake we advanced power to maximum and took an approximately 140 degree heading and escaped the turbulence. We were visually clear of all obstructions and traffic. It seems as though the tower controller issued takeoff clearance with less than normal time separation. Additionally, the departure controller, despite our advisory, gave instructions that would have further endangered our flight by restricting our turn. It may be that 1 or both of these controllers were unaware of the effects of wake turbulence or feel that it's more important to keep aircraft from overflying noise sensitive areas than it is to have them operate safely. Our crew could have asked for increased separation for takeoff.

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Original NASA ASRS Text

Title: ACR MLG WAKE TURB ENCOUNTER IN ICB OFF RWY 17R AT DFW.

Narrative: AFTER TAKING OFF OF RWY 17R AT DFW AND PASSING 1200 FT MSL OUR MLG ENCOUNTERED SEVERE WAKE TURB CREATED BY A PREVIOUSLY DEPARTING LGT. THE PF WAS STRUGGLING TO RETAIN ACFT CTL, USING FULL FLT CTL INPUTS TO COUNTERACT THE ROLL RATE. THE WAKE TURB HAD CHANGED THE ACFT'S HDG TO APPROX 155 DEG FROM THE ASSIGNED 170 DEG RWY HDG. AS THE PNF I TOLD DEP CTL THAT WE WERE ENCOUNTERING SEVERE WAKE TURB AND TURNING L NOW TO GET OUT OF IT. DEP CTL RESPONDED 'NEGATIVE ON THE TURN.' I REINFORMED DEP THAT WE HAD NO CHOICE TO WHICH THEY INSTRUCTED THAT OUR TURN MUST BE LIMITED TO NO MORE THAN 10 DEG. STILL IN THE WAKE WE ADVANCED PWR TO MAX AND TOOK AN APPROX 140 DEG HDG AND ESCAPED THE TURB. WE WERE VISUALLY CLR OF ALL OBSTRUCTIONS AND TFC. IT SEEMS AS THOUGH THE TWR CTLR ISSUED TKOF CLRNC WITH LESS THAN NORMAL TIME SEPARATION. ADDITIONALLY, THE DEP CTLR, DESPITE OUR ADVISORY, GAVE INSTRUCTIONS THAT WOULD HAVE FURTHER ENDANGERED OUR FLT BY RESTRICTING OUR TURN. IT MAY BE THAT 1 OR BOTH OF THESE CTLRS WERE UNAWARE OF THE EFFECTS OF WAKE TURB OR FEEL THAT IT'S MORE IMPORTANT TO KEEP ACFT FROM OVERFLYING NOISE SENSITIVE AREAS THAN IT IS TO HAVE THEM OPERATE SAFELY. OUR CREW COULD HAVE ASKED FOR INCREASED SEPARATION FOR TKOF.

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.