Air carrier descends below what ARTCC assumes to be their cleared altitude.

Attributes
ACN	473550
Time
Date	200005
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : lrp.vortac
State Reference	PA
Altitude	msl single value : 15500
Environment
Flight Conditions	IMC
Weather Elements	Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other
Route In Use	arrival other enroute airway : v143.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : atp pilot : flight engineer pilot : instrument
Experience	flight time last 90 days : 210 flight time total : 3900 flight time type : 747
ASRS Report	473550
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	inflight encounter : turbulence other anomaly other
Independent Detector	other controllerb other flight crewa
Resolutory Action	controller : issued new clearance
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

In and out of scattered clouds and buildups, we asked for a lower altitude (we were at FL200) or slower speed (assigned 300 KIAS). We were assigned 17000 ft and descended. 17000 ft was still a rough ride and we asked for 280 KIAS. We were assigned 280 KIAS by center then a few moments later received a clearance to be at 10000 ft and 250 KIAS at robrt. Passing 15500 ft, the controller asked what was our assigned altitude and we responded that he cleared us to robrt at 10000 ft at 250 KIAS. He disagreed and then assigned us to level off at 14000 ft. Both of us (the captain and myself) were positive that we heard our call sign and the 10000 ft clearance.

Original NASA ASRS Text

Title: ACR DSNDS BELOW WHAT ARTCC ASSUMES TO BE THEIR CLRED ALT.

Narrative: IN AND OUT OF SCATTERED CLOUDS AND BUILDUPS, WE ASKED FOR A LOWER ALT (WE WERE AT FL200) OR SLOWER SPD (ASSIGNED 300 KIAS). WE WERE ASSIGNED 17000 FT AND DSNDED. 17000 FT WAS STILL A ROUGH RIDE AND WE ASKED FOR 280 KIAS. WE WERE ASSIGNED 280 KIAS BY CTR THEN A FEW MOMENTS LATER RECEIVED A CLRNC TO BE AT 10000 FT AND 250 KIAS AT ROBRT. PASSING 15500 FT, THE CTLR ASKED WHAT WAS OUR ASSIGNED ALT AND WE RESPONDED THAT HE CLRED US TO ROBRT AT 10000 FT AT 250 KIAS. HE DISAGREED AND THEN ASSIGNED US TO LEVEL OFF AT 14000 FT. BOTH OF US (THE CAPT AND MYSELF) WERE POSITIVE THAT WE HEARD OUR CALL SIGN AND THE 10000 FT CLRNC.

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.