Narrative:

During a busy session on local control working combined position, lcn, lcs, ccn, and ccs, I cleared a widebody transport X for takeoff. Approximately 1 min later I cleared a widebody transport Y for takeoff. The widebody transport Y was overtaking the preceding aircraft by approximately 60 KTS and a loss of standard separation occurred 4 mi east of the airport. The slow speed of the widebody transport X was the cause of the loss of standard separation. I had anticipated the 4 mi radar separation when I cleared the second aircraft for takeoff.

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Original NASA ASRS Text

Title: LCL CTLR ALLOWED WDB Y TO OVERTAKE WDB X RESULTING IN LTSS.

Narrative: DURING A BUSY SESSION ON LCL CTL WORKING COMBINED POS, LCN, LCS, CCN, AND CCS, I CLRED A WDB X FOR TKOF. APPROX 1 MIN LATER I CLRED A WDB Y FOR TKOF. THE WDB Y WAS OVERTAKING THE PRECEDING ACFT BY APPROX 60 KTS AND A LOSS OF STANDARD SEPARATION OCCURRED 4 MI E OF THE ARPT. THE SLOW SPD OF THE WDB X WAS THE CAUSE OF THE LOSS OF STANDARD SEPARATION. I HAD ANTICIPATED THE 4 MI RADAR SEPARATION WHEN I CLRED THE SECOND ACFT 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.