An ATP GA pilot penetrates the class D of bjc, co.

Attributes
ACN	468990
Time
Date	200004
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bjc.airport
State Reference	CO
Altitude	msl bound lower : 6500 msl bound upper : 2600
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : d01.tracon tower : bjc.tower
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	enroute : direct
Flight Plan	None
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : multi engine pilot : instrument pilot : commercial pilot : atp pilot : cfi
Experience	flight time last 90 days : 160 flight time total : 9000 flight time type : 100
ASRS Report	468990
Person 2
Affiliation	government : faa
Function	controller : local
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : less severe airspace violation : entry non adherence : far other anomaly other
Independent Detector	atc equipment other atc equipment : radar other controllera
Resolutory Action	controller : issued alert flight crew : exited penetrated airspace
Consequence	faa : reviewed incident with flight crew other
Supplementary
Problem Areas	Aircraft ATC Human Performance Airspace Structure
Air Traffic Incident	Pilot Deviation

Narrative:

I requested a clearance to transit bjc's class D airspace from north to south. Tower controller advised he was in the middle of a runway change, was very busy, to maintain above 7500 ft MSL and gave me a frequency to contact denver approach. I contacted denver approach and was given a transponder code. I proceeded south thinking I had approval to enter his airspace. I called him again, was told I was in radar contact but that I was 'in class D airspace,' with an altitude readout of 6500 ft. I stated that my altimeter was reading 7600 ft. He then told me to turn off my mode C transponder. I proceeded south, confident that my altimeter was reading correctly and that the problem was with my transponder. Visually I was certain that I was at 7600 ft since I am very familiar with the area and bjc airport. The problem with the transponder has been reported to the flight club maintenance director. I was rushed and should have remained absolutely clear of class D and class B airspace until confirmed in radar contact, at least then I would not have compromised denver's or bjc's airspace even if the readout on altitude was mistaken. My lesson on this -- slow down and don't assume anything.

Original NASA ASRS Text

Title: AN ATP GA PLT PENETRATES THE CLASS D OF BJC, CO.

Narrative: I REQUESTED A CLRNC TO TRANSIT BJC'S CLASS D AIRSPACE FROM N TO S. TWR CTLR ADVISED HE WAS IN THE MIDDLE OF A RWY CHANGE, WAS VERY BUSY, TO MAINTAIN ABOVE 7500 FT MSL AND GAVE ME A FREQ TO CONTACT DENVER APCH. I CONTACTED DENVER APCH AND WAS GIVEN A XPONDER CODE. I PROCEEDED S THINKING I HAD APPROVAL TO ENTER HIS AIRSPACE. I CALLED HIM AGAIN, WAS TOLD I WAS IN RADAR CONTACT BUT THAT I WAS 'IN CLASS D AIRSPACE,' WITH AN ALT READOUT OF 6500 FT. I STATED THAT MY ALTIMETER WAS READING 7600 FT. HE THEN TOLD ME TO TURN OFF MY MODE C XPONDER. I PROCEEDED S, CONFIDENT THAT MY ALTIMETER WAS READING CORRECTLY AND THAT THE PROB WAS WITH MY XPONDER. VISUALLY I WAS CERTAIN THAT I WAS AT 7600 FT SINCE I AM VERY FAMILIAR WITH THE AREA AND BJC ARPT. THE PROB WITH THE XPONDER HAS BEEN RPTED TO THE FLT CLUB MAINT DIRECTOR. I WAS RUSHED AND SHOULD HAVE REMAINED ABSOLUTELY CLR OF CLASS D AND CLASS B AIRSPACE UNTIL CONFIRMED IN RADAR CONTACT, AT LEAST THEN I WOULD NOT HAVE COMPROMISED DENVER'S OR BJC'S AIRSPACE EVEN IF THE READOUT ON ALT WAS MISTAKEN. MY LESSON ON THIS -- SLOW DOWN AND DON'T ASSUME ANYTHING.

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.