Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Confusion
ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Requested ATC Assistance / Clarification
Procedure
Descending on the BTSEY 2 Arrival into CLT for 36L. After BTSEY the Controller cleared us to CEDOX. We thought we heard DEFOX ON THE 36L Localizer. We tried to query the Controller; but the radios were so congested that we couldn't get a word in. Before we had a chance to ask; the Controller gave us a heading for downwind. As we started to investigate; we found CEDOX on the PARQR 3 Arrival. We noticed that the PARQR 3 is one of the SIDs that we are unable to fly. The PM; on initial check-in gave the Controller all of the required information including the SID we were on and the transition.Recommend changing the name of either CEDOX or DEFOX. They're too similar to be that close together.
Air Carrier Captain reported a track heading deviation during arrival to CLT airport due to similar sounding fix names CEDOX and DEFOX.