Altitude deviation.

Attributes
ACN	298050
Time
Date	199503
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : gcv
State Reference	MS
Altitude	msl bound lower : 31300 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	MD-88
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial
Experience	flight time last 90 days : 145 flight time total : 5020 flight time type : 1818
ASRS Report	298050
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
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 other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Center gave a descent for traffic from FL330 to FL310. We read it back and started the descent. At about FL313, center told us to climb back to FL330, because the descent was for another aircraft. As it turned out, there was a foreign carrier on frequency with a call sign of 'air carrier X abcd.' our call sign was 'air carrier Y aecd.' we were not aware there was an aircraft with a similar call sign on our frequency. We climbed back to FL330. We didn't have to deviate at all and rest of flight was uneventful. Callback conversation with reporter revealed the following information: the reporter flies as first officer on the md-88 for a major united states air carrier. The other aircraft did not respond to the clearance. ARTCC did not correct the reporter's faulty readback and did not notice the error until the reporter was well out of its assigned altitude. ARTCC's demand that the reporter climb back up was the first indication that there was another aircraft on frequency with a similar call sign.

Original NASA ASRS Text

Title: ALTDEV.

Narrative: CTR GAVE A DSCNT FOR TFC FROM FL330 TO FL310. WE READ IT BACK AND STARTED THE DSCNT. AT ABOUT FL313, CTR TOLD US TO CLB BACK TO FL330, BECAUSE THE DSCNT WAS FOR ANOTHER ACFT. AS IT TURNED OUT, THERE WAS A FOREIGN CARRIER ON FREQ WITH A CALL SIGN OF 'ACR X ABCD.' OUR CALL SIGN WAS 'ACR Y AECD.' WE WERE NOT AWARE THERE WAS AN ACFT WITH A SIMILAR CALL SIGN ON OUR FREQ. WE CLBED BACK TO FL330. WE DIDN'T HAVE TO DEVIATE AT ALL AND REST OF FLT WAS UNEVENTFUL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES AS FO ON THE MD-88 FOR A MAJOR UNITED STATES ACR. THE OTHER ACFT DID NOT RESPOND TO THE CLRNC. ARTCC DID NOT CORRECT THE RPTR'S FAULTY READBACK AND DID NOT NOTICE THE ERROR UNTIL THE RPTR WAS WELL OUT OF ITS ASSIGNED ALT. ARTCC'S DEMAND THAT THE RPTR CLB BACK UP WAS THE FIRST INDICATION THAT THERE WAS ANOTHER ACFT ON FREQ WITH A SIMILAR CALL SIGN.

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.