A C172 flight instructor on a left base for the right runway experiences a near midair collision wit...

Narrative:

Approaching from the east; aircraft X was following another C-172 (aircraft Y); who tower claimed to have called up '30 seconds' prior at the same point. Tower directed aircraft X to follow that traffic and report a two mile left base for the left runway. As aircraft X continued to the airport aircraft Z; who had been on the right runway practicing touch-and-goes; requested a transition to the left runway for landing. Aircraft Z was cleared to make the transition to the left runway by entering a right base for the right runway. Right before reporting the two mile right base for aircraft X; aircraft Y was on final and cleared to land; aircraft Z was told they were number two for landing. When aircraft X reported the left base; tower told the pilots they were number two for landing. Aircraft X assumed they were number two behind aircraft X; who was now on short final; not aircraft Z (on the right base). Both aircraft X and aircraft Z started to turn final at the same time; luckily aircraft Z saw what was happening and alerted the tower. Aircraft X was cleared to land on the left runway; while aircraft Z went around. The confusion between the landing order of aircraft was a major contributor to this event. Also; the position of the two converging aircraft was in question.

Original NASA ASRS Text

Title: A C172 Flight Instructor on a left base for the right runway experiences a NMAC with another flight school C172 on a right base for the left runway. The instructor in a third aircraft detects the conflict and goes around.

Narrative: Approaching from the east; Aircraft X was following another C-172 (Aircraft Y); who Tower claimed to have called up '30 seconds' prior at the same point. Tower directed Aircraft X to follow that traffic and report a two mile left base for the left runway. As Aircraft X continued to the airport Aircraft Z; who had been on the right runway practicing touch-and-goes; requested a transition to the left runway for landing. Aircraft Z was cleared to make the transition to the left runway by entering a right base for the right runway. Right before reporting the two mile right base for Aircraft X; Aircraft Y was on final and cleared to land; Aircraft Z was told they were number two for landing. When Aircraft X reported the left base; Tower told the pilots they were number two for landing. Aircraft X assumed they were number two behind Aircraft X; who was now on short final; not Aircraft Z (on the right base). Both Aircraft X and Aircraft Z started to turn final at the same time; luckily Aircraft Z saw what was happening and alerted the Tower. Aircraft X was cleared to land on the left runway; while Aircraft Z went around. The confusion between the landing order of aircraft was a major contributor to this event. Also; the position of the two converging aircraft was in question.

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	971161
Time
Date	201109
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Tower
State Reference	US
Aircraft 1
Make Model Name	Skyhawk 172/Cutlass 172
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	None
Aircraft 2
Make Model Name	Skyhawk 172/Cutlass 172
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	None
Person 1
Function	Instructor
Qualification	Flight Crew Commercial Flight Crew Multiengine Flight Crew Instrument Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 30 Flight Crew Total 275 Flight Crew Type 150
Events
Anomaly	Conflict NMAC
Miss Distance	Horizontal 300 Vertical 50

A C172 flight instructor on a left base for the right runway experiences a near midair collision with another flight school C172 on a right base for the left runway. The instructor in a third aircraft detects the conflict and goes around.