Air carrier X altitude deviation unauthorized descent from assigned altitude.

Attributes
ACN	289687
Time
Date	199411
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : bdf
State Reference	IL
Altitude	msl bound lower : 32500 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zau
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 23500 flight time type : 12000
ASRS Report	289687
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While at cruise at FL330 air carrier X was given a frequency change to ord center. Upon checking in, we were issued clearance to FL290. I responded with, 'roger, air carrier X leaving FL330 for FL290.' shortly after commencing descent (approximately FL326) ord center told us to return to FL330. It became apparent that the clearance to descend was intended for different company X. We deviated 500 ft during that miscom and are unaware of any conflicts which resulted. Similar call signs continue to create problems for us all.

Original NASA ASRS Text

Title: ACR X ALTDEV UNAUTH DSCNT FROM ASSIGNED ALT.

Narrative: WHILE AT CRUISE AT FL330 ACR X WAS GIVEN A FREQ CHANGE TO ORD CTR. UPON CHKING IN, WE WERE ISSUED CLRNC TO FL290. I RESPONDED WITH, 'ROGER, ACR X LEAVING FL330 FOR FL290.' SHORTLY AFTER COMMENCING DSCNT (APPROX FL326) ORD CTR TOLD US TO RETURN TO FL330. IT BECAME APPARENT THAT THE CLRNC TO DSND WAS INTENDED FOR DIFFERENT COMPANY X. WE DEVIATED 500 FT DURING THAT MISCOM AND ARE UNAWARE OF ANY CONFLICTS WHICH RESULTED. SIMILAR CALL SIGNS CONTINUE TO CREATE PROBS FOR US ALL.

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.