Flight crew readback, 'descend to 10000'.' controller had cleared the flight to 11000'.

Attributes
ACN	121156
Time
Date	198908
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : elm
State Reference	NY
Altitude	msl bound lower : 10000 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer pilot : cfi
Experience	flight time last 90 days : 210 flight time total : 6000 flight time type : 800
ASRS Report	121156
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : clearance other anomaly
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were given a clearance to cross gibbe intersection (26 DME north of elm VOR) at 10000'. The captain read back 10000' to the controller. Just before we were given the clearance, our senior F/a came into the cockpit and started talking. This was at the same time the center controller started giving the clearance. I motioned to the first officer to be quiet. For this reason, I missed the clearance that ZOB gave to us, but I heard the readback given as 10000'. I asked what altitude we were given. The captain said 10000'. Upon reaching 10000', ZOB asked to confirm 11000'. We said we were cleared to 10000', and that we had read back 10000'. The center controller said 10000' was ok, and handed us over to roc approach. 10000 and 11000 sound much the same, and are easy to misunderstand. The controller, if he intended us to descend to 11000', should have corrected our readback of 10000'. Our senior F/a should have knocked before entering the cabin. It is a contributing factor here because of the first officer entering the cabin unannounced. A uniform altitude should be used for handing off traffic from center to approach controllers. 10000 and 11000' altitude deviations occur much too often.

Original NASA ASRS Text

Title: FLT CREW READBACK, 'DESCEND TO 10000'.' CTLR HAD CLEARED THE FLT TO 11000'.

Narrative: WE WERE GIVEN A CLRNC TO CROSS GIBBE INTXN (26 DME N OF ELM VOR) AT 10000'. THE CAPT READ BACK 10000' TO THE CTLR. JUST BEFORE WE WERE GIVEN THE CLRNC, OUR SENIOR F/A CAME INTO THE COCKPIT AND STARTED TALKING. THIS WAS AT THE SAME TIME THE CENTER CTLR STARTED GIVING THE CLRNC. I MOTIONED TO THE F/O TO BE QUIET. FOR THIS REASON, I MISSED THE CLRNC THAT ZOB GAVE TO US, BUT I HEARD THE READBACK GIVEN AS 10000'. I ASKED WHAT ALT WE WERE GIVEN. THE CAPT SAID 10000'. UPON REACHING 10000', ZOB ASKED TO CONFIRM 11000'. WE SAID WE WERE CLRED TO 10000', AND THAT WE HAD READ BACK 10000'. THE CENTER CTLR SAID 10000' WAS OK, AND HANDED US OVER TO ROC APCH. 10000 AND 11000 SOUND MUCH THE SAME, AND ARE EASY TO MISUNDERSTAND. THE CTLR, IF HE INTENDED US TO DSND TO 11000', SHOULD HAVE CORRECTED OUR READBACK OF 10000'. OUR SENIOR F/A SHOULD HAVE KNOCKED BEFORE ENTERING THE CABIN. IT IS A CONTRIBUTING FACTOR HERE BECAUSE OF THE F/O ENTERING THE CABIN UNANNOUNCED. A UNIFORM ALT SHOULD BE USED FOR HANDING OFF TFC FROM CENTER TO APCH CTLRS. 10000 AND 11000' ALT DEVIATIONS OCCUR MUCH TOO OFTEN.

Data retrieved from NASA's ASRS site as of August 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.