Potential conflict less than standard separation.

Attributes
ACN	314787
Time
Date	199508
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : dtw
State Reference	MI
Altitude	msl bound lower : 9500 msl bound upper : 11000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dtw
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	other : unknown
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 225 flight time total : 8900 flight time type : 3750
ASRS Report	314787
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : required legal separation non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance flight crew : took evasive action other
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 6000 vertical : 800
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

During vectors to approach at dtw, the very busy approach controller cleared us to descend from 11000 ft to 9000 ft. During our descent received a TCASII RA at about 9800 ft warning us of a conflict at 2 O'clock position, below us and climbing. We received a TCASII climb command and bottomed out about 9500 ft. Notifying the controller, he gave us a climb back to 11000 ft and passing 10500 ft he cleared us 'back to 9000 ft.' dtw ground controller notified us to call for potential altitude deviation!?! There was no doubt in our minds as to the clearance which was read back and set in the altitude alerter.

Original NASA ASRS Text

Title: POTENTIAL CONFLICT LTSS.

Narrative: DURING VECTORS TO APCH AT DTW, THE VERY BUSY APCH CTLR CLRED US TO DSND FROM 11000 FT TO 9000 FT. DURING OUR DSCNT RECEIVED A TCASII RA AT ABOUT 9800 FT WARNING US OF A CONFLICT AT 2 O'CLOCK POS, BELOW US AND CLBING. WE RECEIVED A TCASII CLB COMMAND AND BOTTOMED OUT ABOUT 9500 FT. NOTIFYING THE CTLR, HE GAVE US A CLB BACK TO 11000 FT AND PASSING 10500 FT HE CLRED US 'BACK TO 9000 FT.' DTW GND CTLR NOTIFIED US TO CALL FOR POTENTIAL ALT DEV!?! THERE WAS NO DOUBT IN OUR MINDS AS TO THE CLRNC WHICH WAS READ BACK AND SET IN THE ALT ALERTER.

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.