Tower controller described a loss of runway separation event involving landing and departing aircraf...

Narrative:

I was local assist for our local controller who had taken the position after being off for several days straight. It was a busy hour and it had its technical moments. A C152 was cleared for take off from runway 24 with a cessna 172 on about a mile and a half final. The conflict alert (ca) alarm had gone off as the C152 was rolling for an aircraft in right crosswind to downwind. Our attention was removed from the aircraft on final momentarily. When local noticed separation would not exist he quickly told the C172 to go around after the aircraft had just crossed the threshold; only he called him by the wrong call sign. The C172 never went around and ended up landing safely. Although the C172 had crossed the threshold before the C152 was 3;000 ft; from my vantage point it appeared as if the C152 had offset slightly north of the runway on a heading of 270. Biggest recommendation would be to ease someone back into local after being off for 12 straight days. I feel it would have been far more beneficial had I worked local and had our local controller work the assist position.

Original NASA ASRS Text

Title: Tower Controller described a loss of runway separation event involving landing and departing aircraft; the reporter listing time away from the job as a possible contributing factor.

Narrative: I was Local Assist for our Local Controller who had taken the position after being off for several days straight. It was a busy hour and it had its technical moments. A C152 was cleared for take off from Runway 24 with a Cessna 172 on about a mile and a half final. The Conflict Alert (CA) alarm had gone off as the C152 was rolling for an aircraft in right crosswind to downwind. Our attention was removed from the aircraft on final momentarily. When Local noticed separation would not exist he quickly told the C172 to go around after the aircraft had just crossed the threshold; only he called him by the wrong call sign. The C172 never went around and ended up landing safely. Although the C172 had crossed the threshold before the C152 was 3;000 FT; from my vantage point it appeared as if the C152 had offset slightly north of the runway on a heading of 270. Biggest recommendation would be to ease someone back into Local after being off for 12 straight days. I feel it would have been far more beneficial had I worked Local and had our Local Controller work the assist position.

Data retrieved from NASA's ASRS site as of April 2012 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	979316
Time
Date	201111
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	Cessna 152
Flight Phase	Initial Climb
Route In Use	None
Flight Plan	VFR
Aircraft 2
Make Model Name	Skyhawk 172/Cutlass 172
Flight Phase	Landing
Route In Use	None
Flight Plan	VFR
Person 1
Function	Handoff / Assist
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Deviation - Procedural Published Material / Policy

Tower controller described a loss of runway separation event involving landing and departing aircraft; the reporter listing time away from the job as a possible contributing factor.