An air carrier medium large transport descended thorough its clearance altitude.

Attributes
ACN	246465
Time
Date	199307
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : yqo airport : dtw
State Reference	ON
Altitude	msl bound lower : 32400 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : instrument pilot : commercial
Experience	flight time last 90 days : 220 flight time total : 7500 flight time type : 750
ASRS Report	246465
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

During cruise at FL350 approximately 100 DME east of yqo, ZOB issued us a clearance to cross yqo at FL280. At approximately 63 DME from yqo, ZOB issued a clearance to descend now to FL330. Captain responded that we were descending to FL330 with clearance to cross yqo at FL280. There was no reply or contradiction from center to this reply. As we descended through approximately 32400 MSL, center called to say our clearance was to FL330 and for us to climb back to FL330, which we did. Captain spoke to the ZOB supervisor after landing. He had listened to the tape and verified what I had described above. The descent to FL330 was not stated as an amended clearance, nor was the crossing of yqo at FL280 rescinded.

Original NASA ASRS Text

Title: AN ACR MLG DSNDED THOROUGH ITS CLRNC ALT.

Narrative: DURING CRUISE AT FL350 APPROX 100 DME E OF YQO, ZOB ISSUED US A CLRNC TO CROSS YQO AT FL280. AT APPROX 63 DME FROM YQO, ZOB ISSUED A CLRNC TO DSND NOW TO FL330. CAPT RESPONDED THAT WE WERE DSNDING TO FL330 WITH CLRNC TO CROSS YQO AT FL280. THERE WAS NO REPLY OR CONTRADICTION FROM CTR TO THIS REPLY. AS WE DSNDED THROUGH APPROX 32400 MSL, CTR CALLED TO SAY OUR CLRNC WAS TO FL330 AND FOR US TO CLB BACK TO FL330, WHICH WE DID. CAPT SPOKE TO THE ZOB SUPVR AFTER LNDG. HE HAD LISTENED TO THE TAPE AND VERIFIED WHAT I HAD DESCRIBED ABOVE. THE DSCNT TO FL330 WAS NOT STATED AS AN AMENDED CLRNC, NOR WAS THE XING OF YQO AT FL280 RESCINDED.

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.