Date: 201410
Local time of day: 1801-2400
Location: SFB.Airport, FL
Light: Night
Aircraft: Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Flight phase: Final Approach
Airspace: Class C SFB
ATC / advisory: Tower SFB
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Confusion; Distraction; Situational Awareness
Anomaly: Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Incursion Runway
Detector: Person Air Traffic Control
When detected: Taxi
Result: Air Traffic Control Separated Traffic; Flight Crew Returned To Clearance
Contributing factors: Human Factors; Procedure
Primary problem: Procedure

Narrative: While working Local 1; I had several aircraft on final. The local 2 controller asked if he could circle to land Runway 27 Right.  I told him I had the request depending on traffic load on final.  He then said the winds favor a Landing on 36; and he will hold short of my runway.  I approved and went back to work; I forgot to change the 18/36 strip over that says it is released to ground control.  When my first aircraft landed I advised them to turn Left on runway 18 and right on taxiway bravo; this is a normal exit for a west operation.  The ground controller then questioned me when the aircraft started to turn onto runway 18 that Local 2 had an aircraft landing runway 36. I realized what I had done which I then told the aircraft to expedite the turn onto bravo.  The Local 2 aircraft was about a half mile final when the aircraft started the turn onto Runway 36.  Aircraft X made the turn onto taxiway Bravo and off of runway 36 approximately 15-20 seconds prior to Aircraft Y crossing the threshold for Runway 36.There are a few things that led to this event.  The first problem was forgetting to turn the strip over that reads Runway 18/36 to Ground Control.  It is also not normal for our airport to use Runway 18/36 since it can affect the traffic flow into the airport.  Whenever we are on a West operation it is normal for the Local controller to use runway 18 as an exit since it is almost always the first exit that an aircraft can make when landing the runway.  This started after the airport extended the runway; aircraft usually will land and fail to make the turn at Bravo 7 which causes them to have to continue down the runway to either exit at Runway 18/36 or Romeo. When this happens the aircraft end up at taxi speed between taxiway Bravo 7 and Runway 18/36; which is a few thousand feet.  It is better to use Runway 18/36 for two reasons; it gets the aircraft off the runway quicker and we use taxiway Romeo as a departure point.  There are several things I would have done differently if this was to happen again.  I would not use Runway 18 as an exit in this instance; I would also ask Local 2 to give me an update on where the aircraft is in reference to landing runway 36.  I believe that it would be beneficial for the airport to put a taxiway for planes to exit between Bravo 7 and Runway 18/36.




Synopsis: SFB Tower Controller reports of an incident where he advises an aircraft to turn onto an active runway with an arrival on short final to that runway.  Traffic exits runway before aircraft on final crosses the threshold.