Narrative:

I have been curious why we have so many alpha characters behind call signs. I know many times it's due to same airline flights overlapping for various reasons. Yesterday; trying to satisfy my curiosity; I queried ACARS to see if we were indeed overlapping. Turns out we were only [flight number] 'XXX'. I then queried dispatch as to why we were XXXC vs. XXX. My dispatcher could not provide a reason for the extra character. After a few minutes; I queried our current ATC facility; if they knew why we were XXXC and why we couldn't be just XXX. After a time; the controller called back and told us we were from that point forward. I informed dispatch of the ATC change. My dispatcher then informed me she was filing a report for the change as she was worried about loss of separation. We proceeded to our destination without incident. Upon arrival; after turning on my cell phone; I had a message to contact our duty manager. I did and he encouraged me to file a report for this event and told me I could face some FAA sanctions. I offered my side of the event and he reviewed the transcripts of the ACARS dialogue and softened his view but still thought it was wise to file this report. While driving home; I contacted the dispatch manager to find out the impetus for filing FAA documentation. He said that sometimes ATC directs these alpha characters to differentiate like call signs with other carriers; not necessarily same; just like to help avoid confusion and reduce the likelihood of someone accepting someone else's clearance. I learned something from this event. I don't think this is a major event like an altitude deviation or actual loss of separation between aircraft but am aware that it is not always about just our carrier related to call signs.

Google
 

Original NASA ASRS Text

Title: Air Carrier flight crew expressed bewilderment as why an alpha character was attached to their flight number (call sign).

Narrative: I have been curious why we have so many alpha characters behind call signs. I know many times it's due to same airline flights overlapping for various reasons. Yesterday; trying to satisfy my curiosity; I queried ACARS to see if we were indeed overlapping. Turns out we were only [flight number] 'XXX'. I then queried Dispatch as to why we were XXXC vs. XXX. My Dispatcher could not provide a reason for the extra character. After a few minutes; I queried our current ATC facility; if they knew why we were XXXC and why we couldn't be just XXX. After a time; the Controller called back and told us we were from that point forward. I informed Dispatch of the ATC change. My Dispatcher then informed me she was filing a report for the change as she was worried about loss of separation. We proceeded to our destination without incident. Upon arrival; after turning on my cell phone; I had a message to contact our duty manager. I did and he encouraged me to file a report for this event and told me I could face some FAA sanctions. I offered my side of the event and he reviewed the transcripts of the ACARS dialogue and softened his view but still thought it was wise to file this report. While driving home; I contacted the Dispatch manager to find out the impetus for filing FAA documentation. He said that sometimes ATC directs these alpha characters to differentiate like call signs with other carriers; not necessarily same; just like to help avoid confusion and reduce the likelihood of someone accepting someone else's clearance. I learned something from this event. I don't think this is a major event like an altitude deviation or actual loss of separation between aircraft but am aware that it is not always about just our carrier related to call signs.

Data retrieved from NASA's ASRS site as of July 2013 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.