Narrative:

Departed MD10 off runway 8. Taxied CRJ7 into position and hold. Cleared CRJ7 for takeoff anticipating I would have a minimum of 6 mi separation. The CRJ7 began its takeoff roll quicker than anticipated; the MD10 climbed out slower than anticipated. The end result was 4.5 mi in trail separation; instead of 5 mi.

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Original NASA ASRS Text

Title: DEN LCL CTLR EXPERIENCED OPERROR WHEN UTILIZING ANTICIPATED IN TRAIL DEP SEPARATION WITH CRJ FOLLOWING MD10 HEAVY.

Narrative: DEPARTED MD10 OFF RWY 8. TAXIED CRJ7 INTO POS AND HOLD. CLRED CRJ7 FOR TKOF ANTICIPATING I WOULD HAVE A MINIMUM OF 6 MI SEPARATION. THE CRJ7 BEGAN ITS TKOF ROLL QUICKER THAN ANTICIPATED; THE MD10 CLBED OUT SLOWER THAN ANTICIPATED. THE END RESULT WAS 4.5 MI IN TRAIL SEPARATION; INSTEAD OF 5 MI.

Data retrieved from NASA's ASRS site as of January 2009 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.