B737-300
Air Traffic Control Fully Certified
Situational Awareness
ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Human Factors
A B737 2 mile left base for Runway 14 Visual Approach; a C441 departing Runway 14. The C441 was ready for departure. I issued cleared for immediate take off and exchanged traffic; 'C441 cleared for immediate take off traffic on 2 mile left base. The C441 acknowledged. The B737 was given traffic departing prior to your arrival; the B737 acknowledged with; 'We'll square the base to final.' The C441 took his time rolling. At the time of lift off it appeared that less than 6;000 FT existed between the still airborne B737 and the C441. In the future I will not trust the C441 to comply with an immediate take off clearance; and/or; I would make a decision earlier whether to issue a go around or cancel take off clearance.
Tower Controller described a questionable runway separation event when traffic cleared for an 'immediate take off' failed to respond as expected.