A DA20 instructor pilot reports a near miss event with a C340 in a busy CTAF traffic pattern.

Attributes
ACN	634517
Time
Date	200410
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : pvu.vor
State Reference	UT
Altitude	msl single value : 5500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	climbout : initial
Route In Use	approach : traffic pattern
Flight Plan	VFR
Aircraft 2
Make Model Name	Cessna 340/340A
Flight Phase	descent : approach
Route In Use	approach : traffic pattern arrival : vfr
Person 1
Affiliation	other
Function	instruction : instructor
Qualification	pilot : multi engine pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 103 flight time total : 465 flight time type : 110
ASRS Report	634517
Person 2
Affiliation	other
Function	instruction : trainee
Events
Anomaly	conflict : nmac non adherence : far other anomaly other other spatial deviation
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : insufficient time none taken : anomaly accepted
Miss Distance	horizontal : 0 vertical : 300
Supplementary
Problem Areas	Environmental Factor Airspace Structure Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

It was a typical busy afternoon in provo. There were around 6 planes in the pattern on an instrument approach. We did a touch-and-go behind a departing C152. They departed the pattern straight out so we turned our crosswind. Numerous calls were made on the radio, most of which were getting stepped on to some degree. One that managed to make it through was an arrow coming in on the 45 degree entry for downwind. We had them in sight despite the sun in our eyes (we were wbound at sunset). We made our call turning downwind, arrow on the 45 degree in sight. As we made the turn, about 3 xmissions occurred at the same time, so nothing could be understood. About the point we rolled out on downwind, we saw a twin cessna pass directly below us at a high rate of speed and call turning downwind off the 45 degree entry. They were probably around 200-400 ft below us. The only call we had heard them make was a call 15 mi south about the time we were on final. There was a good possibility that if they made a 45 degree entry call it got blocked by another transmission. The sunset was also a contributing factor because it made it difficult to see things directly in front of us. The twin cessna also made their 45 degree entry to downwind right where we turned from crosswind which reduced the possibility of us noticing them earlier so a gradual correction could be made. The other aircraft did need to maneuver to avoid a collision, but we didn't.

Original NASA ASRS Text

Title: A DA20 INSTRUCTOR PLT RPTS A NEAR MISS EVENT WITH A C340 IN A BUSY CTAF TFC PATTERN.

Narrative: IT WAS A TYPICAL BUSY AFTERNOON IN PROVO. THERE WERE AROUND 6 PLANES IN THE PATTERN ON AN INST APCH. WE DID A TOUCH-AND-GO BEHIND A DEPARTING C152. THEY DEPARTED THE PATTERN STRAIGHT OUT SO WE TURNED OUR XWIND. NUMEROUS CALLS WERE MADE ON THE RADIO, MOST OF WHICH WERE GETTING STEPPED ON TO SOME DEGREE. ONE THAT MANAGED TO MAKE IT THROUGH WAS AN ARROW COMING IN ON THE 45 DEG ENTRY FOR DOWNWIND. WE HAD THEM IN SIGHT DESPITE THE SUN IN OUR EYES (WE WERE WBOUND AT SUNSET). WE MADE OUR CALL TURNING DOWNWIND, ARROW ON THE 45 DEG IN SIGHT. AS WE MADE THE TURN, ABOUT 3 XMISSIONS OCCURRED AT THE SAME TIME, SO NOTHING COULD BE UNDERSTOOD. ABOUT THE POINT WE ROLLED OUT ON DOWNWIND, WE SAW A TWIN CESSNA PASS DIRECTLY BELOW US AT A HIGH RATE OF SPD AND CALL TURNING DOWNWIND OFF THE 45 DEG ENTRY. THEY WERE PROBABLY AROUND 200-400 FT BELOW US. THE ONLY CALL WE HAD HEARD THEM MAKE WAS A CALL 15 MI S ABOUT THE TIME WE WERE ON FINAL. THERE WAS A GOOD POSSIBILITY THAT IF THEY MADE A 45 DEG ENTRY CALL IT GOT BLOCKED BY ANOTHER XMISSION. THE SUNSET WAS ALSO A CONTRIBUTING FACTOR BECAUSE IT MADE IT DIFFICULT TO SEE THINGS DIRECTLY IN FRONT OF US. THE TWIN CESSNA ALSO MADE THEIR 45 DEG ENTRY TO DOWNWIND RIGHT WHERE WE TURNED FROM XWIND WHICH REDUCED THE POSSIBILITY OF US NOTICING THEM EARLIER SO A GRADUAL CORRECTION COULD BE MADE. THE OTHER ACFT DID NEED TO MANEUVER TO AVOID A COLLISION, BUT WE DIDN'T.

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.