Near midair collision in traffic pattern procedure. Problem with pilot judgement of traffic spacing.

Attributes
ACN	280090
Time
Date	199408
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : dpa
State Reference	IL
Altitude	msl bound lower : 1200 msl bound upper : 1200
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : dpa tracon : cid
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	other
Route In Use	approach : visual
Flight Plan	None
Aircraft 2
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	other
Route In Use	approach : visual
Flight Plan	VFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 22 flight time total : 181 flight time type : 4
ASRS Report	280090
Person 2
Affiliation	Other
Function	flight crew : single pilot
Events
Anomaly	conflict : nmac other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 300 vertical : 0
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

ATC cleared my aircraft for left base, runway 28 after reporting 2 mi southeast corner of field and advised I would be following a light twin on right base for runway 28, visual contact was made. Both aircraft were on approximately a head on course with a high closure speed. I immediately began a 360 degree turn to the left to avoid the other aircraft, who also initiated a 360 degree turn to the right. ATC was unaware of anything wrong until my evasive turn was almost complete. After completion of my turn I proceeded to land on runway 28. It took the twin longer to complete his turn and then he also landed on runway 28. I then spoke with the pilot of the twin via telephone. After speaking with the pilot, I called the tower and spoke with the controller who stated it was very busy in the pattern and that his attention was on several other aircraft at the time. Had there been a greater separation of aircraft, this would not have happened.

Original NASA ASRS Text

Title: NMAC IN TFC PATTERN PROC. PROBLEM WITH PLT JUDGEMENT OF TFC SPACING.

Narrative: ATC CLRED MY ACFT FOR L BASE, RWY 28 AFTER RPTING 2 MI SE CORNER OF FIELD AND ADVISED I WOULD BE FOLLOWING A LIGHT TWIN ON R BASE FOR RWY 28, VISUAL CONTACT WAS MADE. BOTH ACFT WERE ON APPROX A HEAD ON COURSE WITH A HIGH CLOSURE SPD. I IMMEDIATELY BEGAN A 360 DEG TURN TO THE L TO AVOID THE OTHER ACFT, WHO ALSO INITIATED A 360 DEG TURN TO THE R. ATC WAS UNAWARE OF ANYTHING WRONG UNTIL MY EVASIVE TURN WAS ALMOST COMPLETE. AFTER COMPLETION OF MY TURN I PROCEEDED TO LAND ON RWY 28. IT TOOK THE TWIN LONGER TO COMPLETE HIS TURN AND THEN HE ALSO LANDED ON RWY 28. I THEN SPOKE WITH THE PLT OF THE TWIN VIA TELEPHONE. AFTER SPEAKING WITH THE PLT, I CALLED THE TWR AND SPOKE WITH THE CTLR WHO STATED IT WAS VERY BUSY IN THE PATTERN AND THAT HIS ATTN WAS ON SEVERAL OTHER ACFT AT THE TIME. HAD THERE BEEN A GREATER SEPARATION OF ACFT, THIS WOULD NOT HAVE HAPPENED.

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.