Narrative:

I was working local control at ewr. I told small transport X to taxi into position and hold runway 29, on departure, turn right heading 230. (I actually meant turn left, but I did not catch my error). I received acknowledgement. I cleared small transport X for takeoff and put the next departure, medium large transport Y into position and hold runway 29, on departure. Turn right heading 300. I received acknowledgement. I looked for small transport X and didn't see him. I figured he'd cranked it around the tower and was obscured from view by the tower roof. I determined small transport X was not where medium large transport Y would be and I cleared medium large transport Y for takeoff. I told small transport X to contact new york departure heading 230. A few seconds later he asked to verify heading 320. I restated '230'. He acknowledged. Doubt is now raised in my mind about exactly what small transport X is doing so I tell him that I lost sight of him and to say position now. He said he was on a 320 heading and then I spotted him as described, on a 320 heading. I told him to continue a left turn and advised him of the medium large transport Y off his left, climbing out of about a thousand, and did he see him. He stated affirmative and I told him to contact ny departure. When I reestablished visual contact with him, I realize there is room to get him on course in front of the medium large transport Y without danger of collision so I applied visual separation in accordance with FAA manual 'ATC', 7110.65F, chapter 7, paragraph 7-10, 'visual separation', part a, 1 and 2. I coordination with departure control about small transport X and medium large transport Y. By now, small transport X is south of medium large transport Y flight path so I told medium large transport Y to contact ny departure. He asked about this traffic 'straight ahead', and I advised him that visual separation was being applied. He acknowledged.

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Original NASA ASRS Text

Title: LTSS BTWN DEPARTING ACFT OFF EWR, LCL CTLR APPLIED VISUAL SEPARATION TOO LATE.

Narrative: I WAS WORKING LCL CTL AT EWR. I TOLD SMT X TO TAXI INTO POS AND HOLD RWY 29, ON DEP, TURN R HDG 230. (I ACTUALLY MEANT TURN L, BUT I DID NOT CATCH MY ERROR). I RECEIVED ACKNOWLEDGEMENT. I CLRED SMT X FOR TKOF AND PUT THE NEXT DEP, MLG Y INTO POS AND HOLD RWY 29, ON DEP. TURN R HDG 300. I RECEIVED ACKNOWLEDGEMENT. I LOOKED FOR SMT X AND DIDN'T SEE HIM. I FIGURED HE'D CRANKED IT AROUND THE TWR AND WAS OBSCURED FROM VIEW BY THE TWR ROOF. I DETERMINED SMT X WAS NOT WHERE MLG Y WOULD BE AND I CLRED MLG Y FOR TKOF. I TOLD SMT X TO CONTACT NEW YORK DEP HDG 230. A FEW SECONDS LATER HE ASKED TO VERIFY HDG 320. I RESTATED '230'. HE ACKNOWLEDGED. DOUBT IS NOW RAISED IN MY MIND ABOUT EXACTLY WHAT SMT X IS DOING SO I TELL HIM THAT I LOST SIGHT OF HIM AND TO SAY POS NOW. HE SAID HE WAS ON A 320 HDG AND THEN I SPOTTED HIM AS DESCRIBED, ON A 320 HDG. I TOLD HIM TO CONTINUE A L TURN AND ADVISED HIM OF THE MLG Y OFF HIS L, CLBING OUT OF ABOUT A THOUSAND, AND DID HE SEE HIM. HE STATED AFFIRMATIVE AND I TOLD HIM TO CONTACT NY DEP. WHEN I REESTABLISHED VISUAL CONTACT WITH HIM, I REALIZE THERE IS ROOM TO GET HIM ON COURSE IN FRONT OF THE MLG Y WITHOUT DANGER OF COLLISION SO I APPLIED VISUAL SEPARATION IN ACCORDANCE WITH FAA MANUAL 'ATC', 7110.65F, CHAPTER 7, PARAGRAPH 7-10, 'VISUAL SEPARATION', PART A, 1 AND 2. I COORD WITH DEP CTL ABOUT SMT X AND MLG Y. BY NOW, SMT X IS S OF MLG Y FLT PATH SO I TOLD MLG Y TO CONTACT NY DEP. HE ASKED ABOUT THIS TFC 'STRAIGHT AHEAD', AND I ADVISED HIM THAT VISUAL SEPARATION WAS BEING APPLIED. HE ACKNOWLEDGED.

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.