Instructor with spi has near midair collision with C172 using improper pattern entry procedures.

Attributes
ACN	324975
Time
Date	199601
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : 50f
State Reference	TX
Altitude	agl bound lower : 1700 agl bound upper : 1700
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : instructional
Make Model Name	Cessna 152
Operating Under FAR Part	Part 91
Flight Phase	descent other other
Flight Plan	None
Aircraft 2
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	descent other other
Person 1
Affiliation	Other
Function	instruction : instructor
Qualification	pilot : cfi pilot : commercial
Experience	flight time last 90 days : 100 flight time total : 360 flight time type : 300
ASRS Report	324975
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : student
Events
Anomaly	conflict : nmac non adherence : far
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 150 vertical : 0
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While flying traffic patterns with a student in a C152 at 50F, a C172 entered the pattern from overhead the field. The C172 executed a descending left turn onto downwind. The pattern is l-hand onto runway 17. As the C172 joined the pattern, he descended over and into the path of our C152. The C152 had to reduce power to idle and execute a steep descending turn to the right to avoid a midair collision. Although the pilot of the C172 made radio calls, they were incorrect and did not justify his position. Incorrect entry procedures were used for pattern flying. The pilot of the C172 was queried on the correct entry procedure. He remained adamant that his procedure was correct. Only way it was discovered was visually. Pilot of C172 should be refreshed on entry procedures, or remain current with the far/aim. I believe the pilot entering the pattern did not bother to enter correctly, nor to hold the position of traffic. In addition, erroneous radio calls helped to further confuse the situation.

Original NASA ASRS Text

Title: INSTRUCTOR WITH SPI HAS NMAC WITH C172 USING IMPROPER PATTERN ENTRY PROCS.

Narrative: WHILE FLYING TFC PATTERNS WITH A STUDENT IN A C152 AT 50F, A C172 ENTERED THE PATTERN FROM OVERHEAD THE FIELD. THE C172 EXECUTED A DSNDING L TURN ONTO DOWNWIND. THE PATTERN IS L-HAND ONTO RWY 17. AS THE C172 JOINED THE PATTERN, HE DSNDED OVER AND INTO THE PATH OF OUR C152. THE C152 HAD TO REDUCE PWR TO IDLE AND EXECUTE A STEEP DSNDING TURN TO THE R TO AVOID A MIDAIR COLLISION. ALTHOUGH THE PLT OF THE C172 MADE RADIO CALLS, THEY WERE INCORRECT AND DID NOT JUSTIFY HIS POS. INCORRECT ENTRY PROCS WERE USED FOR PATTERN FLYING. THE PLT OF THE C172 WAS QUERIED ON THE CORRECT ENTRY PROC. HE REMAINED ADAMANT THAT HIS PROC WAS CORRECT. ONLY WAY IT WAS DISCOVERED WAS VISUALLY. PLT OF C172 SHOULD BE REFRESHED ON ENTRY PROCS, OR REMAIN CURRENT WITH THE FAR/AIM. I BELIEVE THE PLT ENTERING THE PATTERN DID NOT BOTHER TO ENTER CORRECTLY, NOR TO HOLD THE POS OF TFC. IN ADDITION, ERRONEOUS RADIO CALLS HELPED TO FURTHER CONFUSE THE SIT.

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.