Narrative:

On the morning of oct/xx/08 I was working the local position; it was approximately XA56 and was still dark outside. I cleared air carrier X; a B757; for takeoff and then subsequently placed air carrier Y into position and hold. I did not observe that air carrier X was a B757 until after I had issued takeoff clearance to air carrier Y and he was airborne. Upon realization that the preceding aircraft was a B757; I immediately issued caution wake turbulence to air carrier Y and stopped his climb out at 2000 ft; approximately 1500 ft below the B757. I coordinated with the departure controller and advised my supervisor of my mistake. I was relieved from position and an investigation took place. It was determined that takeoff clearance was issued to air carrier Y 1 min 33 seconds after the air carrier X; and initial separation was measured at 3.33 mi. In the early morning hours of the shift; I failed to fully read the flight progress strip and notice that air carrier X was a B757. When looking out the windows at the aircraft themselves in the dark hours; the lights on the air carrier X looked to me to be similar of those of a B737.

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Original NASA ASRS Text

Title: LOCAL CONTROLLER FAILED TO PROVIDE REQUIRED HEAVY JET SEPARATION WHEN CLEARING AN A320 BEHIND A PREVIOUS B757 DEPARTURE; FAILING TO NOTE TYPE ACFT ON STRIP.

Narrative: ON THE MORNING OF OCT/XX/08 I WAS WORKING THE LCL POS; IT WAS APPROX XA56 AND WAS STILL DARK OUTSIDE. I CLRED ACR X; A B757; FOR TKOF AND THEN SUBSEQUENTLY PLACED ACR Y INTO POS AND HOLD. I DID NOT OBSERVE THAT ACR X WAS A B757 UNTIL AFTER I HAD ISSUED TKOF CLRNC TO ACR Y AND HE WAS AIRBORNE. UPON REALIZATION THAT THE PRECEDING ACFT WAS A B757; I IMMEDIATELY ISSUED CAUTION WAKE TURB TO ACR Y AND STOPPED HIS CLBOUT AT 2000 FT; APPROX 1500 FT BELOW THE B757. I COORDINATED WITH THE DEP CTLR AND ADVISED MY SUPVR OF MY MISTAKE. I WAS RELIEVED FROM POS AND AN INVESTIGATION TOOK PLACE. IT WAS DETERMINED THAT TKOF CLRNC WAS ISSUED TO ACR Y 1 MIN 33 SECONDS AFTER THE ACR X; AND INITIAL SEPARATION WAS MEASURED AT 3.33 MI. IN THE EARLY MORNING HRS OF THE SHIFT; I FAILED TO FULLY READ THE FLT PROGRESS STRIP AND NOTICE THAT ACR X WAS A B757. WHEN LOOKING OUT THE WINDOWS AT THE ACFT THEMSELVES IN THE DARK HRS; THE LIGHTS ON THE ACR X LOOKED TO ME TO BE SIMILAR OF THOSE OF A B737.

Data retrieved from NASA's ASRS site as of May 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.