B737-700
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 134; Flight Crew Type 13000
Communication Breakdown
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude
Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action
Airspace Structure; Procedure; Human Factors
During descent on the KOLTT 2 to ATL; we received an RA requiring a climb. Before the RA we attempted to contact Approach numerous times to no avail due to blocked transmissions and high Controller workload. We complied with the RA; attempted to report our altitude excursion again to no avail. After returning to the last assigned clearance we elected to change radios (to the number two) thinking our original radio had failed. We were then called by Approach with the admonishment that for the last '30 miles we have been trying to call you.' At the next frequency change we switched back to the original communication radio (the number one) with no issues. We landed uneventfully.I feel we handled this event well using good airmanship and applied superior CRM skills. In general; two radio voice communications is (in my opinion) a very archaic way of controlling airplanes in congested airspace.
ATL Approach finally responded to our call. It was our sixth to eighth attempt to reach them. We tried COMM 2 and COMM 1 after we established communications with ATL. Both of our systems were operating normally. Also I had Guard frequency in COMM 2 the entire time; and never heard ATL Approach attempt to contact us on Guard.
A B737-700 flight crew reported they had difficulty contacting ATL Approach on a STAR arrival; citing frequency congestion and controller workload as contributing.