Sea ground controller described a confused call sign issue when the wrong strip was placed at local ...

Narrative:

It was my last time on position for the day. I'll have to admit I was pretty tired when I took position because it had been my quick turn. Air carrier X called for taxi and I thought he said air carrier XXX something; when I looked at my strips I had air carrier xxy so I taxied him out to the runway. A couple of minutes later an aircraft that departed tagged up as air carrier xxy and the local controller said that he/she had called him air carrier XXX because that is what strip indicated and the pilot hadn't corrected her; but it was apparently air carrier xxy with air carrier XXX's strip. The aircraft that I had taxied out was air carrier XXX and I had called him air carrier xxy. I honestly don't know if I taxied the first aircraft; normally if I have taxied someone with like sounding call signs; I recognize that and double check so I don't think I had taxied the first carrier outbound; but I can't swear to it. One of the call signs should be changed because this is not the first time that something like this has happened. Also; the numeral X and the numeral Y look very similar on the asde-X and the stars and that can lead to other problems and misunderstandings. Recommendation: the air carrier should change one of the call signs of these aircraft; especially because these aircraft depart different directions and if the local controller is expecting one to turn the opposite direction it could cause a much more serious problem in the air. I should have listened to the little voice that told me I thought he said air carrier XXX rather than air carrier xxy and questioned him. If I had; right then I would have been able to realize what was going on before the local controller departed the other aircraft. Also; neither of the pilots called attention to the fact that both the ground controller and the local controller were calling them by the wrong call signs; basically a failure all along the line. There are other sets of call signs that have created problems as well.

Original NASA ASRS Text

Title: SEA Ground Controller described a confused call sign issue when the wrong strip was placed at Local Control; noting the call signs are similar sounding and very closely numbered.

Narrative: It was my last time on position for the day. I'll have to admit I was pretty tired when I took position because it had been my quick turn. Air Carrier X called for taxi and I thought he said Air Carrier XXX something; when I looked at my strips I had Air Carrier XXY so I taxied him out to the runway. A couple of minutes later an aircraft that departed tagged up as Air Carrier XXY and the Local Controller said that he/she had called him Air Carrier XXX because that is what strip indicated and the pilot hadn't corrected her; but it was apparently Air Carrier XXY with Air Carrier XXX's strip. The aircraft that I had taxied out was Air Carrier XXX and I had called him Air Carrier XXY. I honestly don't know if I taxied the first aircraft; normally if I have taxied someone with like sounding call signs; I recognize that and double check so I don't think I had taxied the first Carrier outbound; but I can't swear to it. One of the call signs should be changed because this is not the first time that something like this has happened. Also; the numeral X and the numeral Y look very similar on the ASDE-X and the STARS and that can lead to other problems and misunderstandings. Recommendation: the Air Carrier should change one of the call signs of these aircraft; especially because these aircraft depart different directions and if the Local Controller is expecting one to turn the opposite direction it could cause a much more serious problem in the air. I should have listened to the little voice that told me I thought he said Air Carrier XXX rather than Air Carrier XXY and questioned him. If I had; right then I would have been able to realize what was going on before the Local Controller departed the other aircraft. Also; neither of the pilots called attention to the fact that both the Ground Controller and the Local Controller were calling them by the wrong call signs; basically a failure all along the line. There are other sets of call signs that have created problems as well.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	952361
Time
Date	201106
Local Time Of Day	0001-0600
Place
Locale Reference	SEA.Airport
State Reference	WA
Aircraft 1
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Flight Plan	IFR
Person 1
Function	Ground
Qualification	Air Traffic Control Fully Certified
Person 2
Function	Handoff / Assist
Qualification	Air Traffic Control Developmental
Events
Anomaly	ATC Issue All Types Deviation - Procedural Published Material / Policy

Sea ground controller described a confused call sign issue when the wrong strip was placed at local control; noting the call signs are similar sounding and very closely numbered.