C172 descends into class B airspace without clearance even though he is talking to the controller.

Attributes
ACN	453100
Time
Date	199910
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dtw.airport
State Reference	MI
Altitude	msl bound lower : 2500 msl bound upper : 8500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : d21.tracon
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	cruise : enroute altitude change
Route In Use	enroute : direct
Flight Plan	None
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 8000 flight time type : 300
ASRS Report	453100
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	airspace violation : entry non adherence : far non adherence : published procedure other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued advisory none taken : detected after the fact
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On oct/xa/99, I was traveling VFR from cleveland, oh, to ann arbor, mi. I was in contact with detroit approach at 8500 ft MSL above the class B ceiling. I announced my position, just south of the class B border, and was also aware that I was in radar contact. I requested a descent to 2500 ft, not requesting specific clearance through the class B as I thought that would be stating the obvious. The clearance to 2500 ft was given and the descent begun. After a few mins, I was asked if I was descending and told that I had not been given class B clearance. I apologized for the misunderstanding and stated that I was under the impression that I did have clearance. I thought my clearance to descend was clearance into class B airspace. In the future, I will not assume it is obvious, but use better communication in requesting and receiving a clearance.

Original NASA ASRS Text

Title: C172 DSNDS INTO CLASS B AIRSPACE WITHOUT CLRNC EVEN THOUGH HE IS TALKING TO THE CTLR.

Narrative: ON OCT/XA/99, I WAS TRAVELING VFR FROM CLEVELAND, OH, TO ANN ARBOR, MI. I WAS IN CONTACT WITH DETROIT APCH AT 8500 FT MSL ABOVE THE CLASS B CEILING. I ANNOUNCED MY POS, JUST S OF THE CLASS B BORDER, AND WAS ALSO AWARE THAT I WAS IN RADAR CONTACT. I REQUESTED A DSCNT TO 2500 FT, NOT REQUESTING SPECIFIC CLRNC THROUGH THE CLASS B AS I THOUGHT THAT WOULD BE STATING THE OBVIOUS. THE CLRNC TO 2500 FT WAS GIVEN AND THE DSCNT BEGUN. AFTER A FEW MINS, I WAS ASKED IF I WAS DSNDING AND TOLD THAT I HAD NOT BEEN GIVEN CLASS B CLRNC. I APOLOGIZED FOR THE MISUNDERSTANDING AND STATED THAT I WAS UNDER THE IMPRESSION THAT I DID HAVE CLRNC. I THOUGHT MY CLRNC TO DSND WAS CLRNC INTO CLASS B AIRSPACE. IN THE FUTURE, I WILL NOT ASSUME IT IS OBVIOUS, BUT USE BETTER COM IN REQUESTING AND RECEIVING A CLRNC.

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.