Unauthorized penetration of class D airspace, proximity of air traffic area.

Attributes
ACN	265106
Time
Date	199403
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : sck airport : ccr
State Reference	CA
Altitude	agl bound lower : 1500 agl bound upper : 1500
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tower : sck
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Navigation In Use	Other
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 30 flight time total : 1320 flight time type : 300
ASRS Report	265106
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	inflight encounter : weather non adherence : far other anomaly other other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact none taken : anomaly accepted
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were on an IFR flight from scottsdale, az, to concord, ca, and had been cleared from near lidat intersection direct ccr. Isolated thunderstorms were evident with cumulus and stratus cloud sloping down from 28000 ft to 6000 ft over the valley. About 50 mi out I was cleared to 6000 ft. Approaching that altitude I was VFR and was approaching some cumulus which looked pretty rough. Since concord ATIS was reporting 2500 ft scattered and the ceiling immediately ahead looked at least that high, I canceled my IFR and descended below the clouds, knowing that there were no obstructions between my position and ccr. At the time of my cancellation, stockton approach switched me to 127.75. I called approach but did not receive a reply. The ceiling in fact turned out to be 2000 ft at my location and upon leveling at 1500 ft I saw that I was just south of stockton airport and probably within their class D airspace. I was out before I could find the tower frequency and received no calls from stockton approach, which makes me think in retrospect that I may have failed to tune 127.75 correctly. I proceeded to concord and landed. I saw no other traffic in the stockton area and perceived no actual conflict. This situation was caused by a last min decision to cancel IFR and descend without knowing my exact position. I thought I was beyond stockton. Since I was cleared to ccr both VOR and GPS navs were on that NAVAID. The airport was blocked by the clouds ahead until it was too late to prevent an incursion. I also should not have assumed the ceiling to be higher than it was.

Original NASA ASRS Text

Title: UNAUTH PENETRATION OF CLASS D AIRSPACE, PROX OF ATA.

Narrative: WE WERE ON AN IFR FLT FROM SCOTTSDALE, AZ, TO CONCORD, CA, AND HAD BEEN CLRED FROM NEAR LIDAT INTXN DIRECT CCR. ISOLATED TSTMS WERE EVIDENT WITH CUMULUS AND STRATUS CLOUD SLOPING DOWN FROM 28000 FT TO 6000 FT OVER THE VALLEY. ABOUT 50 MI OUT I WAS CLRED TO 6000 FT. APCHING THAT ALT I WAS VFR AND WAS APCHING SOME CUMULUS WHICH LOOKED PRETTY ROUGH. SINCE CONCORD ATIS WAS RPTING 2500 FT SCATTERED AND THE CEILING IMMEDIATELY AHEAD LOOKED AT LEAST THAT HIGH, I CANCELED MY IFR AND DSNDED BELOW THE CLOUDS, KNOWING THAT THERE WERE NO OBSTRUCTIONS BTWN MY POS AND CCR. AT THE TIME OF MY CANCELLATION, STOCKTON APCH SWITCHED ME TO 127.75. I CALLED APCH BUT DID NOT RECEIVE A REPLY. THE CEILING IN FACT TURNED OUT TO BE 2000 FT AT MY LOCATION AND UPON LEVELING AT 1500 FT I SAW THAT I WAS JUST S OF STOCKTON ARPT AND PROBABLY WITHIN THEIR CLASS D AIRSPACE. I WAS OUT BEFORE I COULD FIND THE TWR FREQ AND RECEIVED NO CALLS FROM STOCKTON APCH, WHICH MAKES ME THINK IN RETROSPECT THAT I MAY HAVE FAILED TO TUNE 127.75 CORRECTLY. I PROCEEDED TO CONCORD AND LANDED. I SAW NO OTHER TFC IN THE STOCKTON AREA AND PERCEIVED NO ACTUAL CONFLICT. THIS SIT WAS CAUSED BY A LAST MIN DECISION TO CANCEL IFR AND DSND WITHOUT KNOWING MY EXACT POS. I THOUGHT I WAS BEYOND STOCKTON. SINCE I WAS CLRED TO CCR BOTH VOR AND GPS NAVS WERE ON THAT NAVAID. THE ARPT WAS BLOCKED BY THE CLOUDS AHEAD UNTIL IT WAS TOO LATE TO PREVENT AN INCURSION. I ALSO SHOULD NOT HAVE ASSUMED THE CEILING TO BE HIGHER THAN IT WAS.

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.