Narrative:

The departing aircraft was instructed to 'taxi into position and hold.' traffic was on 7 mi final but had not yet checked on. When he did check on, the developmental cleared him to land and advised him of traffic holding in position. The developmental then went back and advised the traffic in position of the traffic on final (as required). The pilot responded with what sounded like 'roger, holding on runway 30L,' but which (upon reviewing the tapes) was actually 'rolling on runway 30L.' he departed 2 mi in trail of the previous aircraft instead of the required (by LOA) 5 mi. Factors involved were poor controller technique. Developmental should have advised of traffic on final at time of clearance into position. Also, nonstandard phraseology by pilot -- should have read back 'cleared for takeoff' if he thought he was cleared.

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Original NASA ASRS Text

Title: DEVELOPMENTAL TWR CTLR CAUSED A LOSS OF LEGAL SEPARATION WITH ANOTHER DEPARTED ACFT, WHEN A B737, HOLDING IN POS FOR TKOF, MISUNDERSTOOD TWR CTLR INSTRUCTIONS TO HOLD POS FOR TKOF CLRNC, AND TOOK OFF.

Narrative: THE DEPARTING ACFT WAS INSTRUCTED TO 'TAXI INTO POS AND HOLD.' TFC WAS ON 7 MI FINAL BUT HAD NOT YET CHKED ON. WHEN HE DID CHK ON, THE DEVELOPMENTAL CLRED HIM TO LAND AND ADVISED HIM OF TFC HOLDING IN POS. THE DEVELOPMENTAL THEN WENT BACK AND ADVISED THE TFC IN POS OF THE TFC ON FINAL (AS REQUIRED). THE PLT RESPONDED WITH WHAT SOUNDED LIKE 'ROGER, HOLDING ON RWY 30L,' BUT WHICH (UPON REVIEWING THE TAPES) WAS ACTUALLY 'ROLLING ON RWY 30L.' HE DEPARTED 2 MI IN TRAIL OF THE PREVIOUS ACFT INSTEAD OF THE REQUIRED (BY LOA) 5 MI. FACTORS INVOLVED WERE POOR CTLR TECHNIQUE. DEVELOPMENTAL SHOULD HAVE ADVISED OF TFC ON FINAL AT TIME OF CLRNC INTO POS. ALSO, NONSTANDARD PHRASEOLOGY BY PLT -- SHOULD HAVE READ BACK 'CLRED FOR TKOF' IF HE THOUGHT HE WAS CLRED.

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.