Pilot complies with bogus clearance to descend.

Attributes
ACN	317159
Time
Date	199509
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mli
State Reference	IL
Altitude	msl bound lower : 5600 msl bound upper : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau
Operator	general aviation : corporate
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 128 flight time total : 5078 flight time type : 30
ASRS Report	317159
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : reviewed incident with flight crew
Supplementary
Air Traffic Incident	other

Narrative:

At 7000 ft, eastbound on V-8 we were handed off from quad city approach to ZAU. We checked in, the controller acknowledged. About 5 mins later, I heard a weak radio transmission, sounded like it might have been for us, I didn't respond. About 30 seconds later I heard it again I responded 'was that for ---?' the voice said 'affirmative descend and maintain 4000 ft.' it was a different voice from the earlier ZAU controller. We acknowledged 'out of 7 for 4.' out of 5600 ft and descending, ZAU (earlier controller voice) called and asked 'verify assigned altitude?' 'is out of 56 for 40 as assigned' I replied. Chicago 'we did not issue you a descent clearance maintain 6000 ft.' I told the controller I was issued a clearance to descend to 4000 ft. I maintained 6000 ft and continued the flight. Upon reaching my destination the center supervisor called. I told him of our situation he said it would be investigated.

Original NASA ASRS Text

Title: PLT COMPLIES WITH BOGUS CLRNC TO DSND.

Narrative: AT 7000 FT, EBOUND ON V-8 WE WERE HANDED OFF FROM QUAD CITY APCH TO ZAU. WE CHKED IN, THE CTLR ACKNOWLEDGED. ABOUT 5 MINS LATER, I HEARD A WEAK RADIO XMISSION, SOUNDED LIKE IT MIGHT HAVE BEEN FOR US, I DIDN'T RESPOND. ABOUT 30 SECONDS LATER I HEARD IT AGAIN I RESPONDED 'WAS THAT FOR ---?' THE VOICE SAID 'AFFIRMATIVE DSND AND MAINTAIN 4000 FT.' IT WAS A DIFFERENT VOICE FROM THE EARLIER ZAU CTLR. WE ACKNOWLEDGED 'OUT OF 7 FOR 4.' OUT OF 5600 FT AND DSNDING, ZAU (EARLIER CTLR VOICE) CALLED AND ASKED 'VERIFY ASSIGNED ALT?' 'IS OUT OF 56 FOR 40 AS ASSIGNED' I REPLIED. CHICAGO 'WE DID NOT ISSUE YOU A DSCNT CLRNC MAINTAIN 6000 FT.' I TOLD THE CTLR I WAS ISSUED A CLRNC TO DSND TO 4000 FT. I MAINTAINED 6000 FT AND CONTINUED THE FLT. UPON REACHING MY DEST THE CTR SUPVR CALLED. I TOLD HIM OF OUR SIT HE SAID IT WOULD BE INVESTIGATED.

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.