Local controller trainee reported an aircraft turned in too close to the preceding aircraft it was t...

Attributes
ACN	1402608
Time
Date	201611
Local Time Of Day	1801-2400
Place
Locale Reference	PRC.Tower
State Reference	AZ
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Cessna 310/T310C
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Route In Use	Visual Approach
Flight Plan	None
Aircraft 2
Make Model Name	Cessna Single Piston Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Flight Plan	None
Person 1
Function	Local
Qualification	Air Traffic Control Developmental
Events
Anomaly	ATC Issue All Types Conflict NMAC

Narrative:

I was working the local control position. Aircraft X was given number two; follow a cessna on a left base to a three mile final. Aircraft X was looking for traffic. Aircraft Y was given runway 21L cleared for touch and go. Aircraft X reported the traffic in sight. Aircraft X was given runway 21L cleared for touch and go. I noticed aircraft X's target turned base quickly so I picked up the binoculars to look for both aircraft. I noticed aircraft X was close behind aircraft Y and instructed aircraft X to go around offset left. Aircraft X read back go around. Aircraft X appeared to be offset on the left. Aircraft Y reported the twin cessna flew under him 50 feet. Aircraft X was on upwind ahead of aircraft Y. Aircraft Y reiterated the twin cessna flew under him 50 feet and said he wanted to report near midair collision. I didn't understand the acronym he gave. My instructor keyed up and said roger. I later found out in our debrief that aircraft Y said 'near midair collision' and that it was a near midair collision.

Original NASA ASRS Text

Title: Local Controller trainee reported an aircraft turned in too close to the preceding aircraft it was to follow and issued go-around instructions. The preceding aircraft filed a NMAC.

Narrative: I was working the Local Control position. Aircraft X was given number two; follow a Cessna on a left base to a three mile final. Aircraft X was looking for traffic. Aircraft Y was given Runway 21L cleared for touch and go. Aircraft X reported the traffic in sight. Aircraft X was given Runway 21L cleared for touch and go. I noticed Aircraft X's target turned base quickly so I picked up the binoculars to look for both aircraft. I noticed Aircraft X was close behind Aircraft Y and instructed Aircraft X to go around offset left. Aircraft X read back go around. Aircraft X appeared to be offset on the left. Aircraft Y reported the Twin Cessna flew under him 50 feet. Aircraft X was on upwind ahead of Aircraft Y. Aircraft Y reiterated the Twin Cessna flew under him 50 feet and said he wanted to report NMAC. I didn't understand the acronym he gave. My instructor keyed up and said roger. I later found out in our debrief that Aircraft Y said 'NMAC' and that it was a near midair collision.

Data retrieved from NASA's ASRS site 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.

Local controller trainee reported an aircraft turned in too close to the preceding aircraft it was to follow and issued go-around instructions. The preceding aircraft filed a near midair collision.