Small transport and small aircraft have near midair collision within air traffic area.

Attributes
ACN	236028
Time
Date	199303
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : smo
State Reference	CA
Altitude	agl bound lower : 900 agl bound upper : 900
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : smo
Operator	general aviation : personal
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	climbout : initial
Flight Plan	VFR
Aircraft 2
Operator	other
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	climbout : intermediate altitude
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : cfi pilot : instrument
Experience	flight time last 90 days : 25 flight time total : 2500 flight time type : 350
ASRS Report	236028
Person 2
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Events
Anomaly	conflict : nmac
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	vertical : 40
Supplementary
Primary Problem	Flight Crew Human Performance

Narrative:

I had departed santa monica airport, cleared by the tower to proceed straight out to the shoreline and then northwest along the coast. Suddenly an small aircraft towing a banner was directly in front of me. I had to dive so violently that all of the loose objects in the airplane were thrown against the ceiling of the cabin. I believe that the banner towing aircraft was not at the altitude that he had been cleared for, to pass through the control zone. I really don't have any corrective actions to suggest. It appeared the banner towing airport turned inland after the episode. My guess is that he had begun his climb prematurely. Part of the visual problem probably occurred due to the tow plane being higher than I was, and I was climbing up to him. He was hidden by my cabin ceiling until I was very close. It is conceivable that I could have climbed into him with an aft part of my aircraft and never have seen him.

Original NASA ASRS Text

Title: SMT AND SMA HAVE NMAC WITHIN ATA.

Narrative: I HAD DEPARTED SANTA MONICA ARPT, CLRED BY THE TWR TO PROCEED STRAIGHT OUT TO THE SHORELINE AND THEN NW ALONG THE COAST. SUDDENLY AN SMA TOWING A BANNER WAS DIRECTLY IN FRONT OF ME. I HAD TO DIVE SO VIOLENTLY THAT ALL OF THE LOOSE OBJECTS IN THE AIRPLANE WERE THROWN AGAINST THE CEILING OF THE CABIN. I BELIEVE THAT THE BANNER TOWING ACFT WAS NOT AT THE ALT THAT HE HAD BEEN CLRED FOR, TO PASS THROUGH THE CTL ZONE. I REALLY DON'T HAVE ANY CORRECTIVE ACTIONS TO SUGGEST. IT APPEARED THE BANNER TOWING ARPT TURNED INLAND AFTER THE EPISODE. MY GUESS IS THAT HE HAD BEGUN HIS CLB PREMATURELY. PART OF THE VISUAL PROBLEM PROBABLY OCCURRED DUE TO THE TOW PLANE BEING HIGHER THAN I WAS, AND I WAS CLBING UP TO HIM. HE WAS HIDDEN BY MY CABIN CEILING UNTIL I WAS VERY CLOSE. IT IS CONCEIVABLE THAT I COULD HAVE CLBED INTO HIM WITH AN AFT PART OF MY ACFT AND NEVER HAVE SEEN HIM.

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.