EMB ERJ 170/175 ER/LR
Communication Breakdown; Situational Awareness; Confusion
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Company Policy; Human Factors; Procedure
Charlotte was in a north operation; and Atlanta Center slowed us to 250 KTS just prior to SHINE. Upon checking in with CLT Approach; the Controller increased our speed to 290 KTS and pointed out Dash-8 traffic a few miles ahead. He descended us to 11;000 FT; and we overtook the Dash; which was at 9;000 FT; with a speed differential of approximately 50 KTS. A similar call sign Company; ABCD; was on frequency; and the Controller slowed them to 210 KTS and descended them to 6;000 FT. Immediately after that transmission; CLT issued 'Company ABED; thanks for the help with the speed; descend and maintain nine thousand FT.' The First Officer was off frequency; so I acknowledged his thanks and readback the assignment to 9;000 and began the descent. A moment later as I was about to level at 9;000 FT; the Controller pointed us out to the Dash; which had us in sight; and told him to maintain visual separation. He followed with our call sign and said 'you're supposed to be at 10;000 FT; maintain 9;000 FT.' The First Officer asked if I'd like to make the response; and I did. I replied 'Company ABED; we'll maintain 9;000 FT. You might want to mark the tape and check that'. His reply was 'don't worry about it; contact CLT Approach.' I'm human and make mistakes; but I'm certain I heard him say 9;000 FT; and I read back 9;000 FT as I was pointing to it and reading it in the altitude preselect field. But to be sure; I asked the crew of Company ABCD on the ground if they'd heard the exchange. Their Captain had been off the frequency at the time; but his First Officer indicated he heard ATC assign us 9;000 FT. I attempted to find the internet recording to include as an attachment to this report; but apparently that frequency isn't one of those monitored. Suggestions; with a thousand available call signs in the Company A000 series; it's reprehensible that we have so many similar-sounding and otherwise confusing call signs in use simultaneously in the same airspace. Monitor other facilities sometime during an arrival bank and you'll hear the occasional frustration in the Controllers' voices. Actually; more frequently than frustration; you'll hear mistakes; which is understandable because we're all human; but can result in loss of separation as in today's case; or worse. While the Controller today used the correct call sign; all the controllers along the way have difficulty keeping them straight. Whoever assigns the call signs should do a geographic analysis of the flights to ensure that no call signs with only one digit different are allowed to be sent to the same region simultaneously.
Air Carrier landing CLT described a confused descent clearance event most likely resulting due to same Company similar sounding call signs; the reporter acknowledging that his Company needs to correct the problem.