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.