Flight crew of large transport took clearance meant for another aircraft. Descending, had TCASII TA.

Attributes
ACN	200014
Time
Date	199112
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dqo
State Reference	MD
Altitude	msl bound lower : 25500 msl bound upper : 26000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc tower : tlh
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : commercial pilot : flight engineer pilot : instrument
Experience	flight time last 90 days : 155 flight time total : 16000
ASRS Report	200014
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : required legal separation other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : took evasive action flight crew : returned to intended course or assigned course
Consequence	Other
Miss Distance	horizontal : 16000 vertical : 400
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Pilot Deviation Operational Error

Narrative:

After coming on to busy east coast frequency, we copied: xx cross holey at 11000 philly altimeter 2980. As captain/check airman I read back the clearance and in full using xx simultaneously resetting altitude on FD panel. I went to FMC to set VNAV crossing holey (?) not in FMC. I checked approach chart no holey (?) something wrong. Meantime first officer had initiated an idle descent (3500 FPM). A TA...I acknowledged. TCASII oncoming traffic. Something is wrong. I took aircraft from student first officer. 'I've got it.' while trying to call center I took autoplt off, autothrottles off, and started leveling aircraft. Power up and climbing back to altitude. More communications from center. We were only hearing call sign numbers, not company identify. YYY called to confirm their clearance. Now the problem was solved. I had read back the clearance intended for YYY. Why didn't someone tell me we had 2 aircraft on frequency with same call sign. Why didn't controller repeat call sign of company? I complained to controller. More communication problems. ZZZ complained. Controller was replaced. After discussing with my supervisor I called TCASII representative and company manager for ATC communication and manager handling industry wide similar call signs. I have since found out from transcripts that aircraft deviation of 2.75 NM and 400 ft.

Original NASA ASRS Text

Title: FLC OF LGT TOOK CLRNC MEANT FOR ANOTHER ACFT. DSNDING, HAD TCASII TA.

Narrative: AFTER COMING ON TO BUSY E COAST FREQ, WE COPIED: XX CROSS HOLEY AT 11000 PHILLY ALTIMETER 2980. AS CAPT/CHK AIRMAN I READ BACK THE CLRNC AND IN FULL USING XX SIMULTANEOUSLY RESETTING ALT ON FD PANEL. I WENT TO FMC TO SET VNAV XING HOLEY (?) NOT IN FMC. I CHKED APCH CHART NO HOLEY (?) SOMETHING WRONG. MEANTIME FO HAD INITIATED AN IDLE DSCNT (3500 FPM). A TA...I ACKNOWLEDGED. TCASII ONCOMING TFC. SOMETHING IS WRONG. I TOOK ACFT FROM STUDENT FO. 'I'VE GOT IT.' WHILE TRYING TO CALL CENTER I TOOK AUTOPLT OFF, AUTOTHROTTLES OFF, AND STARTED LEVELING ACFT. PWR UP AND CLBING BACK TO ALT. MORE COMS FROM CENTER. WE WERE ONLY HEARING CALL SIGN NUMBERS, NOT COMPANY IDENT. YYY CALLED TO CONFIRM THEIR CLRNC. NOW THE PROBLEM WAS SOLVED. I HAD READ BACK THE CLRNC INTENDED FOR YYY. WHY DIDN'T SOMEONE TELL ME WE HAD 2 ACFT ON FREQ WITH SAME CALL SIGN. WHY DIDN'T CTLR REPEAT CALL SIGN OF COMPANY? I COMPLAINED TO CTLR. MORE COM PROBLEMS. ZZZ COMPLAINED. CTLR WAS REPLACED. AFTER DISCUSSING WITH MY SUPVR I CALLED TCASII REPRESENTATIVE AND COMPANY MGR FOR ATC COM AND MGR HANDLING INDUSTRY WIDE SIMILAR CALL SIGNS. I HAVE SINCE FOUND OUT FROM TRANSCRIPTS THAT ACFT DEV OF 2.75 NM AND 400 FT.

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.