Tpa controller experienced a developing ground conflict when failing to observe a taxiing aircraft. ...

Narrative:

I taxied the SF34 to runway 19L via taxiway C. A few minutes later the B737 called ready to taxi. I issued taxi instructions to the B737 to runway 19R via C; B8; B and V taxiway. When I issued this; I had the B737 insight; I did not see any other aircraft in his way. The SF34 that I taxied; I did not see; I assumed he had already departed. The SF34 was actually on taxiway C; but he was obstructed from my view by the tdw display monitor. I didn't move from the spot that I was standing at because to my right was the console and to my left was my chair that I offered to other personnel. The B737 assumed that I had instructed the SF34 to give way to him; and began to taxi out as instructed. The SF34 continued to taxi. The B737 had to stop and give way to the SF34. I could have moved around and better scanned the taxi route prior to issuing the taxi clearance. I also recommend that the tdw display be lowered; so that the view of a major taxiway and the main entering/exiting point for taxing aircraft is not obstructed.

Original NASA ASRS Text

Title: TPA Controller experienced a developing ground conflict when failing to observe a taxiing aircraft. The reporter listed tower equipment placement and not moving around as contributing factors.

Narrative: I taxied the SF34 to Runway 19L via Taxiway C. A few minutes later the B737 called ready to taxi. I issued taxi instructions to the B737 to Runway 19R via C; B8; B and V Taxiway. When I issued this; I had the B737 insight; I did not see any other aircraft in his way. The SF34 that I taxied; I did not see; I assumed he had already departed. The SF34 was actually on Taxiway C; but he was obstructed from my view by the TDW display monitor. I didn't move from the spot that I was standing at because to my right was the console and to my left was my chair that I offered to other personnel. The B737 assumed that I had instructed the SF34 to give way to him; and began to taxi out as instructed. The SF34 continued to taxi. The B737 had to stop and give way to the SF34. I could have moved around and better scanned the taxi route prior to issuing the taxi clearance. I also recommend that the TDW display be lowered; so that the view of a major taxiway and the main entering/exiting point for taxing aircraft is not obstructed.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1006840
Time
Date	201204
Local Time Of Day	0601-1200
Place
Locale Reference	TPA.Airport
State Reference	FL
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Flight Plan	IFR
Aircraft 2
Make Model Name	Saab 340 Undifferentiated
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Route In Use	None
Flight Plan	IFR
Person 1
Function	Ground
Qualification	Air Traffic Control Developmental
Person 2
Function	First Officer
Experience	Flight Crew Last 90 Days 26
Events
Anomaly	ATC Issue All Types Conflict Ground Conflict Less Severe Deviation - Procedural Clearance

Tpa controller experienced a developing ground conflict when failing to observe a taxiing aircraft. The reporter listed tower equipment placement and not moving around as contributing factors.