Altitude excursion by air carrier medium large transport responding to wrong call sign.

Attributes
ACN	103932
Time
Date	198902
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : abe
State Reference	NY
Altitude	msl bound lower : 8900 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
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	arrival other 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 : 150 flight time total : 13400 flight time type : 150
ASRS Report	103930
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	controller : issued new clearance flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

At approximately XA20Z, 2/wed/89, while descending to 11000' about 10 NM west of allentown VOR, both the copilot and I heard a clearance which we thought was for us to descend to 8000'. The copilot read back, 'medium large transport down to 8.' approaching 11000' I asked the copilot, 'cleared to 8000?' and he responded affirmatively. At about 8900' ZNY asked our altitude and said we had never been cleared below 11000' to climb back to 11000, which we did immediately. The center claimed it never cleared us to 8000', nor heard our readback. In retrospect, the clearance may have been for another flight, but we thought it was for us and read back same. Human factors considerations include the fact that with heavy communications loads at the time, the center wasn't using full calls signs (prefixed with company) and our readback was also abbreviated. The fact that the center often doesn't listen to a readback is also part of the problem.

Original NASA ASRS Text

Title: ALT EXCURSION BY ACR MLG RESPONDING TO WRONG CALL SIGN.

Narrative: AT APPROX XA20Z, 2/WED/89, WHILE DSNDING TO 11000' ABOUT 10 NM W OF ALLENTOWN VOR, BOTH THE COPLT AND I HEARD A CLRNC WHICH WE THOUGHT WAS FOR US TO DSND TO 8000'. THE COPLT READ BACK, 'MLG DOWN TO 8.' APCHING 11000' I ASKED THE COPLT, 'CLRED TO 8000?' AND HE RESPONDED AFFIRMATIVELY. AT ABOUT 8900' ZNY ASKED OUR ALT AND SAID WE HAD NEVER BEEN CLRED BELOW 11000' TO CLB BACK TO 11000, WHICH WE DID IMMEDIATELY. THE CENTER CLAIMED IT NEVER CLRED US TO 8000', NOR HEARD OUR READBACK. IN RETROSPECT, THE CLRNC MAY HAVE BEEN FOR ANOTHER FLT, BUT WE THOUGHT IT WAS FOR US AND READ BACK SAME. HUMAN FACTORS CONSIDERATIONS INCLUDE THE FACT THAT WITH HEAVY COMS LOADS AT THE TIME, THE CENTER WASN'T USING FULL CALLS SIGNS (PREFIXED WITH COMPANY) AND OUR READBACK WAS ALSO ABBREVIATED. THE FACT THAT THE CENTER OFTEN DOESN'T LISTEN TO A READBACK IS ALSO PART OF THE PROB.

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.