Narrative:

Began takeoff with minimum distance behind previous aircraft, maintaining visual on that aircraft, and assigned the same departure heading (125 degrees). At approximately 500 ft AGL, I entered his vortex and was unable to out climb the turbulence. I then deviated from normal departure procedure and lowered the nose, reduced my climb rate and proceeded below the problem area. Shortly I was given a different heading and was able to resume normal climb procedures. Comment: I believe when two aircraft are departing with minimum separation, they should be assigned diverging headings to minimize the problem. Most jet transport aircraft have similar performance, so it stands to reason we are flying in each other's vortex. Just after lift-off is of particular concern. Callback conversation with reporter revealed the following information: callback was completed as part of the special wake turbulence incident questionnaire. Reporter captain verified his aircraft was a DC9-30 and the aircraft in front was an MD80. He estimated the wind very light -- less than 5 KTS and from the southeast and because the WX and visibility were good the tower was departing aircraft in close trail. As one aircraft was off the runway the next cleared for takeoff and spacing was less than 2 mi and assigned headings were runway heading, 125 degrees. Shortly after the gear was up, 500 ft, reporter aircraft experienced moderate turbulence from the MD80 ahead and aircraft rolled 40 degrees both right and left. Reporter lowered nose to fly out of the wake and experienced no more. Shortly they were handed off to departure controller and a new heading was assigned. Reporter says that tower should assign divergent headings to eliminate this problem and it shouldn't affect traffic control at all. After the encounter the passenger were concerned as reporter captain knew they would be, he made a PA announcement to advise the passenger of what occurred. He says that's another reason that flcs shouldn't be put in that position of soothing passenger when the encounter could have been avoided in the first place.

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Original NASA ASRS Text

Title: DC9-30 ACFT DEPARTING IN TRAIL OF AN MD80 ACFT ON THE SAME DEP HEADING, ENCOUNTERED MODERATE TURB FROM THE PRECEDING ACFT WAKE. RPTR CAPT LOWERED THE NOSE OF HIS ACFT TO STAY BELOW THE WAKE AND EXITED THE TURB.

Narrative: BEGAN TKOF WITH MINIMUM DISTANCE BEHIND PREVIOUS ACFT, MAINTAINING VISUAL ON THAT ACFT, AND ASSIGNED THE SAME DEP HEADING (125 DEGS). AT APPROX 500 FT AGL, I ENTERED HIS VORTEX AND WAS UNABLE TO OUT CLB THE TURB. I THEN DEVIATED FROM NORMAL DEP PROC AND LOWERED THE NOSE, REDUCED MY CLB RATE AND PROCEEDED BELOW THE PROB AREA. SHORTLY I WAS GIVEN A DIFFERENT HEADING AND WAS ABLE TO RESUME NORMAL CLB PROCS. COMMENT: I BELIEVE WHEN TWO ACFT ARE DEPARTING WITH MINIMUM SEPARATION, THEY SHOULD BE ASSIGNED DIVERGING HEADINGS TO MINIMIZE THE PROB. MOST JET TRANSPORT ACFT HAVE SIMILAR PERFORMANCE, SO IT STANDS TO REASON WE ARE FLYING IN EACH OTHER'S VORTEX. JUST AFTER LIFT-OFF IS OF PARTICULAR CONCERN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: CALLBACK WAS COMPLETED AS PART OF THE SPECIAL WAKE TURB INCIDENT QUESTIONNAIRE. RPTR CAPT VERIFIED HIS ACFT WAS A DC9-30 AND THE ACFT IN FRONT WAS AN MD80. HE ESTIMATED THE WIND VERY LIGHT -- LESS THAN 5 KTS AND FROM THE SE AND BECAUSE THE WX AND VISIBILITY WERE GOOD THE TWR WAS DEPARTING ACFT IN CLOSE TRAIL. AS ONE ACFT WAS OFF THE RWY THE NEXT CLRED FOR TKOF AND SPACING WAS LESS THAN 2 MI AND ASSIGNED HEADINGS WERE RWY HEADING, 125 DEGS. SHORTLY AFTER THE GEAR WAS UP, 500 FT, RPTR ACFT EXPERIENCED MODERATE TURB FROM THE MD80 AHEAD AND ACFT ROLLED 40 DEGS BOTH R AND L. RPTR LOWERED NOSE TO FLY OUT OF THE WAKE AND EXPERIENCED NO MORE. SHORTLY THEY WERE HANDED OFF TO DEP CTLR AND A NEW HEADING WAS ASSIGNED. RPTR SAYS THAT TWR SHOULD ASSIGN DIVERGENT HEADINGS TO ELIMINATE THIS PROB AND IT SHOULDN'T AFFECT TFC CTL AT ALL. AFTER THE ENCOUNTER THE PAX WERE CONCERNED AS RPTR CAPT KNEW THEY WOULD BE, HE MADE A PA ANNOUNCEMENT TO ADVISE THE PAX OF WHAT OCCURRED. HE SAYS THAT'S ANOTHER REASON THAT FLCS SHOULDN'T BE PUT IN THAT POS OF SOOTHING PAX WHEN THE ENCOUNTER COULD HAVE BEEN AVOIDED IN THE FIRST PLACE.

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.