Flight crew responded to another company aircraft's descent clearance.

Attributes
ACN	458540
Time
Date	199912
Day	Tue
Local Time Of Day	1801 To 2400
Place
State Reference	NJ
Altitude	msl bound lower : 13000 msl bound upper : 19000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	A310
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 60 flight time total : 4950 flight time type : 850
ASRS Report	458540
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 30 flight time total : 9000 flight time type : 700
ASRS Report	458389
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	atc equipment other atc equipment : mode c other controllera
Resolutory Action	controller : issued new clearance controller : issued alert
Consequence	faa : reviewed incident with flight crew other
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft ATC Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

First officer's leg, dtw-ewr, A310, departing approximately XA00. I was working the radios and began to have problems transmitting about 45 mins into the flight. In attempting to troubleshoot the problem, I tried swapping headsets, tried the hand microphone, while the first officer was flying and backing me up on the radio calls. During the troubleshooting, we also swapped back and forth who was flying. As the radio situation progressed I was hand flying the aircraft. In the midst of this rather confusing situation, the first officer read back an altitude clearance of 13000 ft. 13000 ft was set in the fcp and confirmed by me. During the descent to 13000 ft, ZNY informed us we were not cleared out of altitude and that we had read back one of our company's clrncs. Because of the confusion in the cockpit due to our communication #1 problem, I was not absolutely certain that the clearance to 13000 ft was for us. Meanwhile center cleared us down further to 9000 ft. We were not aware of any conflicts with the aircraft.

Original NASA ASRS Text

Title: FLC RESPONDED TO ANOTHER COMPANY ACFT'S DSCNT CLRNC.

Narrative: FO'S LEG, DTW-EWR, A310, DEPARTING APPROX XA00. I WAS WORKING THE RADIOS AND BEGAN TO HAVE PROBS XMITTING ABOUT 45 MINS INTO THE FLT. IN ATTEMPTING TO TROUBLESHOOT THE PROB, I TRIED SWAPPING HEADSETS, TRIED THE HAND MIKE, WHILE THE FO WAS FLYING AND BACKING ME UP ON THE RADIO CALLS. DURING THE TROUBLESHOOTING, WE ALSO SWAPPED BACK AND FORTH WHO WAS FLYING. AS THE RADIO SIT PROGRESSED I WAS HAND FLYING THE ACFT. IN THE MIDST OF THIS RATHER CONFUSING SIT, THE FO READ BACK AN ALT CLRNC OF 13000 FT. 13000 FT WAS SET IN THE FCP AND CONFIRMED BY ME. DURING THE DSCNT TO 13000 FT, ZNY INFORMED US WE WERE NOT CLRED OUT OF ALT AND THAT WE HAD READ BACK ONE OF OUR COMPANY'S CLRNCS. BECAUSE OF THE CONFUSION IN THE COCKPIT DUE TO OUR COM #1 PROB, I WAS NOT ABSOLUTELY CERTAIN THAT THE CLRNC TO 13000 FT WAS FOR US. MEANWHILE CTR CLRED US DOWN FURTHER TO 9000 FT. WE WERE NOT AWARE OF ANY CONFLICTS WITH THE ACFT.

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.