Medium Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Confusion
ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Procedure; Company Policy; Human Factors
During descent into CLT had Company flight ABA come on same frequency. Immediately noticed that AB and ABA we're difficult to differentiate on a busy frequency. The F/O and I discussed the problems when the company assigns similar sounding call signs; particularly at busy airports or in international airspace. A few times there was confusion as to whom ATC was talking to; both by ATC and by the crews. The last clearance which we responded to was a descent to 4000.  There was later a clearance for a turn and intercept LOC for 18C which was either issued to or accepted by ABA. As we approached the LOC ATC was very busy and we were waiting for our clearance to intercept when we received a 'TRAFFIC' advisory from TCAS. I increased our rate of descent to avoid a resolution advisory when ATC told us to increase our rate to 4000. He then asked us why we were not turning onto the LOC as cleared. We responded that we had NOT received any clearance other than descend and maintain 4000. We were broken out of the sequence and reslotted. It is unclear whether the controller issued our clearance to ABA or ABA took our clearance. Even during the final approach tower was getting the two flights confused. Similar sounding call sign.  This problem keeps reoccurring and simply MUST stop.  Whomever makes these decisions should listen to an ATC recording with the rapid fire of flight numbers; similar sounding flight numbers from other airlines; talk over transmissions; clearances; amended clearances and all; of the other assorted typical issues involving radio ops at a major airport.  Then MAYBE they will get the idea that selecting flight numbers to ease internal tracking can result in confusion aloft; a reduction in efficiency; increase in fuel burn (like this flight) and a potential degradation in safety (ie: our nose-to-nose with the traffic intercepting the LOC from the opposite side).
Air carrier Captain describes the confusion that ensues when a company aircraft comes on the Approach Control frequency with a nearly identical call sign.