Near midair collision uncontrolled airport traffic pattern.

Attributes
ACN	111143
Time
Date	198905
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : 069
State Reference	CA
Altitude	msl bound lower : 1050 msl bound upper : 1050
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : hio
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	descent : approach other
Flight Plan	None
Aircraft 2
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	climbout : intermediate altitude climbout : initial
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 12 flight time total : 200 flight time type : 25
ASRS Report	111143
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 none taken : insufficient time
Consequence	Other
Miss Distance	vertical : 50
Supplementary
Primary Problem	Flight Crew Human Performance

Narrative:

I was entering the pattern at petaluma municipal and just as I was about to make my downwind call for runway 29R traffic, I saw a blue small aircraft Y, either an xx or xy, out the passenger window on my right. He was climbing out and we were on a collision course. He had just departed petaluma municipal on runway 29 and was making a right downwind departure. I was able to reduce my power and descend quickly. The small aircraft Y passed over me approximately 50'. I landed and reported the incident to the airport manager. I don't recall the north # of the small aircraft Y. I'm not sure why this incident occurred. I had reported that I was inbound at a 45 degree angle for runway 29R traffic--and I heard the small aircraft Y make his departure call. I was looking for him and he should have been looking for me. I was flying an small aircraft X, and I had my navigation light, my anti-collision light and the landing light on!

Original NASA ASRS Text

Title: NMAC UNCONTROLLED ARPT TRAFFIC PATTERN.

Narrative: I WAS ENTERING THE PATTERN AT PETALUMA MUNI AND JUST AS I WAS ABOUT TO MAKE MY DOWNWIND CALL FOR RWY 29R TFC, I SAW A BLUE SMA Y, EITHER AN XX OR XY, OUT THE PAX WINDOW ON MY RIGHT. HE WAS CLBING OUT AND WE WERE ON A COLLISION COURSE. HE HAD JUST DEPARTED PETALUMA MUNI ON RWY 29 AND WAS MAKING A RIGHT DOWNWIND DEP. I WAS ABLE TO REDUCE MY PWR AND DSND QUICKLY. THE SMA Y PASSED OVER ME APPROX 50'. I LANDED AND RPTED THE INCIDENT TO THE ARPT MGR. I DON'T RECALL THE N # OF THE SMA Y. I'M NOT SURE WHY THIS INCIDENT OCCURRED. I HAD RPTED THAT I WAS INBND AT A 45 DEG ANGLE FOR RWY 29R TFC--AND I HEARD THE SMA Y MAKE HIS DEP CALL. I WAS LOOKING FOR HIM AND HE SHOULD HAVE BEEN LOOKING FOR ME. I WAS FLYING AN SMA X, AND I HAD MY NAV LIGHT, MY ANTI-COLLISION LIGHT AND THE LNDG LIGHT ON!

Data retrieved from NASA's ASRS site as of August 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.