Air carrier X descent below assigned altitude.

Attributes
ACN	298320
Time
Date	199503
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : lrp
State Reference	NY
Altitude	msl bound lower : 10000 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : csg
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 enroute airway : zny
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 205 flight time total : 16106 flight time type : 10144
ASRS Report	298320
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : overshoot non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

Air carrier X, dtw to phl. On bucks 3 arrival (har.BUCKS3). ZNY cleared us to 10000 ft. We acknowledged. Immediately after acknowledging, center cleared us to cross bouhn at 11000 ft. We thought that this was in addition to the clearance to descend to 10000 ft. We crossed bouhn at 11000 ft, and then continued down to 10000 ft. Almost at the lancaster VOR (lrp) center asked us what our altitude was. We stated 10000 ft. He said that he meant for us to cross bouhn and maintain 11000 ft. He said, 'that's okay.' he did indicate that he understood how the previously issued clearance could have been misunderstood. He said, 'just maintain 10000 ft now, there is no problem.'

Original NASA ASRS Text

Title: ACR X DSCNT BELOW ASSIGNED ALT.

Narrative: ACR X, DTW TO PHL. ON BUCKS 3 ARR (HAR.BUCKS3). ZNY CLRED US TO 10000 FT. WE ACKNOWLEDGED. IMMEDIATELY AFTER ACKNOWLEDGING, CTR CLRED US TO CROSS BOUHN AT 11000 FT. WE THOUGHT THAT THIS WAS IN ADDITION TO THE CLRNC TO DSND TO 10000 FT. WE CROSSED BOUHN AT 11000 FT, AND THEN CONTINUED DOWN TO 10000 FT. ALMOST AT THE LANCASTER VOR (LRP) CTR ASKED US WHAT OUR ALT WAS. WE STATED 10000 FT. HE SAID THAT HE MEANT FOR US TO CROSS BOUHN AND MAINTAIN 11000 FT. HE SAID, 'THAT'S OKAY.' HE DID INDICATE THAT HE UNDERSTOOD HOW THE PREVIOUSLY ISSUED CLRNC COULD HAVE BEEN MISUNDERSTOOD. HE SAID, 'JUST MAINTAIN 10000 FT NOW, THERE IS NO PROB.'

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.