A B757 flight crew leaves their previously assigned altitude of FL350 when they possibly answer to a...

Attributes
ACN	466590
Time
Date	200003
Day	Fri
Local Time Of Day	0601 To 1200
Place
State Reference	SC
Altitude	msl bound lower : 31000 msl bound upper : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zjx.artcc
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : enroute altitude change
Route In Use	enroute airway : j79.airway
Flight Plan	IFR
Person 1
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 16000 flight time type : 700
ASRS Report	466590
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : multi engine
Events
Anomaly	non adherence : published procedure non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Airspace Structure ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Level at FL350. ATC said, 'air carrier X, descend and maintain FL310.' captain responded, 'air carrier X, out of FL350 for FL310.' while descending, ATC said, 'air carrier X say your altitude.' captain responded, 'air carrier X passing FL325 for FL310.' ATC said we were not given a clearance to FL310. Then ATC said 'air carrier X descend and maintain FL310.' captain said 'air carrier X descending to FL310.' possibly one or more of many reasons. 1) possibly, ATC 'meant clearance' for another aircraft, but verbally said our call sign. 2) possibly, ATC actually gave clearance to another aircraft, and the captain incorrectly read back the clearance, thinking it was for his aircraft. If this was the case, then ATC failed to notice an incorrect 'call sign' reading back his clearance, that was intended for a different aircraft. If ATC used incorrect call sign, (for a clearance meant for a different aircraft), ATC should double-check for correct call sign usage. Also, upon crew member reading back a clearance to ATC, listen closely for correct call sign reading back clearance. For crew: listen very closely for whom a clearance is intended. Contributing factors: the captain did not 'question' ATC's clearance, because the time/position was normal for such a descent. Also, the first officer did not question the clearance, or the readback, either.

Original NASA ASRS Text

Title: A B757 FLC LEAVES THEIR PREVIOUSLY ASSIGNED ALT OF FL350 WHEN THEY POSSIBLY ANSWER TO A WRONG CALL SIGN FOR A LOWER ALT NEAR AND, SC.

Narrative: LEVEL AT FL350. ATC SAID, 'ACR X, DSND AND MAINTAIN FL310.' CAPT RESPONDED, 'ACR X, OUT OF FL350 FOR FL310.' WHILE DSNDING, ATC SAID, 'ACR X SAY YOUR ALT.' CAPT RESPONDED, 'ACR X PASSING FL325 FOR FL310.' ATC SAID WE WERE NOT GIVEN A CLRNC TO FL310. THEN ATC SAID 'ACR X DSND AND MAINTAIN FL310.' CAPT SAID 'ACR X DSNDING TO FL310.' POSSIBLY ONE OR MORE OF MANY REASONS. 1) POSSIBLY, ATC 'MEANT CLRNC' FOR ANOTHER ACFT, BUT VERBALLY SAID OUR CALL SIGN. 2) POSSIBLY, ATC ACTUALLY GAVE CLRNC TO ANOTHER ACFT, AND THE CAPT INCORRECTLY READ BACK THE CLRNC, THINKING IT WAS FOR HIS ACFT. IF THIS WAS THE CASE, THEN ATC FAILED TO NOTICE AN INCORRECT 'CALL SIGN' READING BACK HIS CLRNC, THAT WAS INTENDED FOR A DIFFERENT ACFT. IF ATC USED INCORRECT CALL SIGN, (FOR A CLRNC MEANT FOR A DIFFERENT ACFT), ATC SHOULD DOUBLE-CHK FOR CORRECT CALL SIGN USAGE. ALSO, UPON CREW MEMBER READING BACK A CLRNC TO ATC, LISTEN CLOSELY FOR CORRECT CALL SIGN READING BACK CLRNC. FOR CREW: LISTEN VERY CLOSELY FOR WHOM A CLRNC IS INTENDED. CONTRIBUTING FACTORS: THE CAPT DID NOT 'QUESTION' ATC'S CLRNC, BECAUSE THE TIME/POS WAS NORMAL FOR SUCH A DSCNT. ALSO, THE FO DID NOT QUESTION THE CLRNC, OR THE READBACK, EITHER.

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.

A B757 flight crew leaves their previously assigned altitude of FL350 when they possibly answer to a wrong call sign for a lower altitude near and, sc.