C172 instructor reports an near midair collision with another C172 in the traffic pattern at sgs. Th...

Narrative:

I am a cfii and was coaching an instrument student through the localizer approach to runway 34 at sgs (south st. Paul; mn). ATC cleared us for the approach. There was another small skyhawk ahead of us flying the same approach. ATC told us that the plane was 4 miles ahead of us and told us to change to advisory frequency. (Winds at sgs were reported calm. The designated calm wind runway is 16). At approximately 5 NM from the runway we heard an archer pilot call departure from runway 16 and staying in the pattern. Just outside the airport traffic pattern; I spotted the archer coming directly towards us. I banked sharply to the right; as did the archer. We entered the downwind leg for runway 16. About mid-field we heard the skyhawk call and say that we had just flown past him; passing within 100 ft. We never saw the plane. The student and I never expected to see the skyhawk in the traffic pattern; since he was reported 4 miles ahead of us. The skyhawk pilot must have slowed considerably upon reaching the airport traffic pattern. My student's airspeed was approximately 20 KTS faster than I normally recommend; but I failed to notice this. This could explain some; but certainly not all; of the diminished spacing between our airplane and the skyhawk. After calling us; the skyhawk pilot asked our intentions. I reported we would enter a base leg and land. He replied that he would exit and re-enter the traffic pattern to increase spacing. The archer pilot reported back farther back on the downwind leg. This situation was caused primarily because I failed to notice the student's excessive airspeed on the traffic pattern and because I did not instruct the student to break off the approach and move to enter the downwind leg soon enough. The student and I both failed to see the skyhawk ahead of us on downwind.

Original NASA ASRS Text

Title: C172 instructor reports an NMAC with another C172 in the traffic pattern at SGS. The reporter and his student never saw the other aircraft and the NMAC report is second hand; from the other pilot.

Narrative: I am a CFII and was coaching an instrument student through the LOC approach to Runway 34 at SGS (South St. Paul; MN). ATC cleared us for the approach. There was another small Skyhawk ahead of us flying the same approach. ATC told us that the plane was 4 miles ahead of us and told us to change to Advisory Frequency. (Winds at SGS were reported calm. The designated calm wind Runway is 16). At approximately 5 NM from the runway we heard an Archer pilot call departure from Runway 16 and staying in the pattern. Just outside the airport traffic pattern; I spotted the Archer coming directly towards us. I banked sharply to the right; as did the Archer. We entered the downwind leg for Runway 16. About mid-field we heard the Skyhawk call and say that we had just flown past him; passing within 100 FT. We never saw the plane. The student and I never expected to see the Skyhawk in the traffic pattern; since he was reported 4 miles ahead of us. The Skyhawk pilot must have slowed considerably upon reaching the airport traffic pattern. My student's airspeed was approximately 20 KTS faster than I normally recommend; but I failed to notice this. This could explain some; but certainly not all; of the diminished spacing between our airplane and the Skyhawk. After calling us; the Skyhawk pilot asked our intentions. I reported we would enter a base leg and land. He replied that he would exit and re-enter the traffic pattern to increase spacing. The Archer pilot reported back farther back on the downwind leg. This situation was caused primarily because I failed to notice the student's excessive airspeed on the traffic pattern and because I did not instruct the student to break off the approach and move to enter the downwind leg soon enough. The student and I both failed to see the Skyhawk ahead of us on downwind.

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.

Attributes
ACN	1158491
Time
Date	201403
Local Time Of Day	1201-1800
Place
Locale Reference	SGS.Airport
State Reference	MN
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Route In Use	None
Flight Plan	VFR
Aircraft 2
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Person 1
Function	Pilot Not Flying Instructor
Qualification	Flight Crew Flight Instructor Flight Crew Commercial Flight Crew Instrument
Experience	Flight Crew Last 90 Days 20 Flight Crew Total 1585 Flight Crew Type 1300
Events
Anomaly	Conflict NMAC Deviation - Procedural Published Material / Policy
Miss Distance	Horizontal 100

C172 instructor reports an near midair collision with another C172 in the traffic pattern at sgs. The reporter and his student never saw the other aircraft and the near midair collision report is second hand; from the other pilot.