Small aircraft X had less than standard separation from small aircraft Y. System error.

Attributes
ACN	135987
Time
Date	199002
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : rdg
State Reference	PA
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	ground : holding
Flight Plan	VFR
Aircraft 2
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	landing other
Flight Plan	VFR
Person 1
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Experience	controller military : 4 controller radar : 12
ASRS Report	135987
Person 2
Affiliation	Other
Function	flight crew : single pilot
Events
Anomaly	conflict : ground less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	unspecified : 2200 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Local control was moderate. Workload was mostly student and led by the hand. Commuter landed. I put small aircraft X into position and hold at mid-runway intersection. Other traffic in the pattern and crossing traffic on a practice instrument approach on another runway. My attention was diverted to this crossing traffic. The small aircraft X on runway was not cleared for takeoff. Small aircraft Y landing was in the flare. I used small aircraft X's call sign for small aircraft Y about to land to, 'go around.' small aircraft X on the runway then rolled for takeoff. Both aircraft numbers were similar. Aircraft on the runway had just been in the pattern with me for 30 mins. Taxied to the drop off instructor before taxiing back out. Usually ground control is combined with local. However training was in progress on ground and approach control (tracab). My view of runways was a bit restr because of all the personnel in the tower. I got caught concentrating my attention to the pattern. When I returned my scan to the runway, I had lost runway separation, then confused the call signs. Small aircraft X rolling and small aircraft Y landing had about 2200' separation.

Original NASA ASRS Text

Title: SMA X HAD LESS THAN STANDARD SEPARATION FROM SMA Y. SYSTEM ERROR.

Narrative: LCL CTL WAS MODERATE. WORKLOAD WAS MOSTLY STUDENT AND LED BY THE HAND. COMMUTER LANDED. I PUT SMA X INTO POSITION AND HOLD AT MID-RWY INTXN. OTHER TFC IN THE PATTERN AND XING TFC ON A PRACTICE INSTRUMENT APCH ON ANOTHER RWY. MY ATTN WAS DIVERTED TO THIS XING TFC. THE SMA X ON RWY WAS NOT CLRED FOR TKOF. SMA Y LNDG WAS IN THE FLARE. I USED SMA X'S CALL SIGN FOR SMA Y ABOUT TO LAND TO, 'GO AROUND.' SMA X ON THE RWY THEN ROLLED FOR TKOF. BOTH ACFT NUMBERS WERE SIMILAR. ACFT ON THE RWY HAD JUST BEEN IN THE PATTERN WITH ME FOR 30 MINS. TAXIED TO THE DROP OFF INSTRUCTOR BEFORE TAXIING BACK OUT. USUALLY GND CTL IS COMBINED WITH LCL. HOWEVER TRAINING WAS IN PROGRESS ON GND AND APCH CTL (TRACAB). MY VIEW OF RWYS WAS A BIT RESTR BECAUSE OF ALL THE PERSONNEL IN THE TWR. I GOT CAUGHT CONCENTRATING MY ATTN TO THE PATTERN. WHEN I RETURNED MY SCAN TO THE RWY, I HAD LOST RWY SEPARATION, THEN CONFUSED THE CALL SIGNS. SMA X ROLLING AND SMA Y LNDG HAD ABOUT 2200' SEPARATION.

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.