Narrative:

There were only a couple of planes on the scope due to bad weather so it was incredibly slow. I was waiting for flight XXXX to check on. I was discussing issues with a fellow controller when company flight xxyy checked on. At the time; I was only aware of the call sign sounding like what I was expecting so I advised 'flight XXXX descend and maintain 80'. Unaware to me flight xxyy read back descending. Shortly after cleveland called and had me level off flight xxyy. It was at this time that I realized that I had two company flights on my frequency and one was not supposed to be there. The best I could recommend would be to have reminders periodically posted to listen for read backs and to give situations like this as how easy it is to miss something.

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Original NASA ASRS Text

Title: LAN Controller described an airspace procedural error caused by a missed read back involving same company aircraft with similar sounding call signs.

Narrative: There were only a couple of planes on the scope due to bad weather so it was incredibly slow. I was waiting for Flight XXXX to check on. I was discussing issues with a fellow controller when company Flight XXYY checked on. At the time; I was only aware of the call sign sounding like what I was expecting so I advised 'Flight XXXX descend and maintain 80'. Unaware to me Flight XXYY read back descending. Shortly after Cleveland called and had me level off Flight XXYY. It was at this time that I realized that I had two company flights on my frequency and one was not supposed to be there. The best I could recommend would be to have reminders periodically posted to listen for read backs and to give situations like this as how easy it is to miss something.

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.