Close proximity GA-small aircraft commuter-small transport near sfo TCA floor.

Attributes
ACN	110232
Time
Date	198905
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : pao
State Reference	CA
Altitude	msl bound lower : 3950 msl bound upper : 3950
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other cruise other
Flight Plan	None
Aircraft 2
Make Model Name	Small Transport
Flight Phase	cruise other
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 60 flight time total : 2700 flight time type : 2000
ASRS Report	110232
Person 2
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : nmac
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	Other
Miss Distance	horizontal : 400 vertical : 100
Supplementary
Primary Problem	Flight Crew Human Performance

Narrative:

Departed pao toward coast for aerobatic hop. Had leveled out at 3800' to stay under TCA (base 4000') until passing osi 150 degree right, where climb is allowed to 6000'. Momentarily distracted by LORAN/VOR in flight check--looked up and saw a commercial jet descending at my 12 O'clock. Since he looked close, I checked my altitude, saw I had gained 100-150' (up to 3950'). Started an immediate descent and saw an small transport at my 9 O'clock at approximately 400' pass just behind me. If I had not started a descent, we would have been extremely close (the small transport and I). To prevent this type of situation, neither of us should have been that close to the controled airspace limit. I should have stayed at approximately 3500'. No one should have been assigned 4000' at that location; it is too close to the adjoining TCA level which borders non-controled airspace.

Original NASA ASRS Text

Title: CLOSE PROX GA-SMA COMMUTER-SMT NEAR SFO TCA FLOOR.

Narrative: DEPARTED PAO TOWARD COAST FOR AEROBATIC HOP. HAD LEVELED OUT AT 3800' TO STAY UNDER TCA (BASE 4000') UNTIL PASSING OSI 150 DEG R, WHERE CLB IS ALLOWED TO 6000'. MOMENTARILY DISTRACTED BY LORAN/VOR IN FLT CHK--LOOKED UP AND SAW A COMMERCIAL JET DSNDING AT MY 12 O'CLOCK. SINCE HE LOOKED CLOSE, I CHKED MY ALT, SAW I HAD GAINED 100-150' (UP TO 3950'). STARTED AN IMMEDIATE DSCNT AND SAW AN SMT AT MY 9 O'CLOCK AT APPROX 400' PASS JUST BEHIND ME. IF I HAD NOT STARTED A DSCNT, WE WOULD HAVE BEEN EXTREMELY CLOSE (THE SMT AND I). TO PREVENT THIS TYPE OF SITUATION, NEITHER OF US SHOULD HAVE BEEN THAT CLOSE TO THE CTLED AIRSPACE LIMIT. I SHOULD HAVE STAYED AT APPROX 3500'. NO ONE SHOULD HAVE BEEN ASSIGNED 4000' AT THAT LOCATION; IT IS TOO CLOSE TO THE ADJOINING TCA LEVEL WHICH BORDERS NON-CTLED AIRSPACE.

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.