Air carrier call sign confusion with similar call signs creates an altitude deviation.

Attributes
ACN	143309
Time
Date	199004
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : tys
State Reference	TN
Altitude	msl bound lower : 27000 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 18000 flight time type : 2100
ASRS Report	143309
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 160 flight time total : 6000 flight time type : 1500
ASRS Report	143464
Events
Anomaly	altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	Pilot Deviation Operational Deviation

Narrative:

Airlines flight AB1 climbing to FL280. ZID gave clearance to FL330. All 3 crew members heard clearance for air carrier flight AB1 to climb to FL330, and captain acknowledged the climb to ZID ARTCC. Passing approximately FL280, center called, 'air carrier flight AB1, you were cleared to FL270, not 330. Air carrier flight AB7 was cleared to 330.' flight was subsequently cleared to FL330 and proceeded to destination west/O further problem. Controller stated that perhaps flight AB1 had acknowledged at the same time as AB7, but this is unlikely as it would have produced an overload squeal and the controller would have been obliged to query for a correct acknowledgement. Supplemental information from acn 143464: ZID ARTCC made a comment that we should be listening up for our call sign. I believe this system works both ways--readbacks are the only way to ensure clrncs.

Original NASA ASRS Text

Title: ACR CALL SIGN CONFUSION WITH SIMILAR CALL SIGNS CREATES AN ALT DEVIATION.

Narrative: AIRLINES FLT AB1 CLBING TO FL280. ZID GAVE CLRNC TO FL330. ALL 3 CREW MEMBERS HEARD CLRNC FOR ACR FLT AB1 TO CLB TO FL330, AND CAPT ACKNOWLEDGED THE CLB TO ZID ARTCC. PASSING APPROX FL280, CENTER CALLED, 'ACR FLT AB1, YOU WERE CLRED TO FL270, NOT 330. ACR FLT AB7 WAS CLRED TO 330.' FLT WAS SUBSEQUENTLY CLRED TO FL330 AND PROCEEDED TO DEST W/O FURTHER PROB. CTLR STATED THAT PERHAPS FLT AB1 HAD ACKNOWLEDGED AT THE SAME TIME AS AB7, BUT THIS IS UNLIKELY AS IT WOULD HAVE PRODUCED AN OVERLOAD SQUEAL AND THE CTLR WOULD HAVE BEEN OBLIGED TO QUERY FOR A CORRECT ACKNOWLEDGEMENT. SUPPLEMENTAL INFO FROM ACN 143464: ZID ARTCC MADE A COMMENT THAT WE SHOULD BE LISTENING UP FOR OUR CALL SIGN. I BELIEVE THIS SYS WORKS BOTH WAYS--READBACKS ARE THE ONLY WAY TO ENSURE CLRNCS.

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.