Date: 201307
Local time of day: 1801-2400
Location: ATL.Airport, GA
Flight conditions: VMC
Light: Daylight
Aircraft: Regional Jet 700 ER/LR (CRJ700)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B ATL
ATC / advisory: TRACON A80
Aircraft component: Air/Ground Communication
Component problem: Improperly Operated; Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Communication Breakdown
Second reporter function: Pilot Flying; First Officer
Anomaly: Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Human Factors; Aircraft
Primary problem: Ambiguous

Narrative: We were receiving vectors from the final Approach Controller for the visual approach to Runway 28 in ATL. We had been given a turn to a heading of 360 degrees which was perpendicular to the final approach course to Runway 28. We were asked if we had the traffic in sight that we would be following; in which we responded in the affirmative. As we got within about 3 miles of the final approach course for Runway 28; the First Officer and I both questioned each other whether they were going to turn us in time to intercept. I; the pilot not flying; queried ATC as soon as radio traffic allowed. We were close to the final approach course with a 90 degree intercept at that point and ATC immediately gave us a turn to the southwest. We complied with the instructions as we overshot the localizer course for Runway 28 and encroached on the approach airspace for Runway 27L. We were told that we were on the wrong frequency. We were given the correct frequency. After checking in with final Approach Control for Runway 28; we were cleared for the visual approach. At some point while being vectored to final; the frequency got changed from the final Approach Controller to the initial Approach Controller. I do not know how the frequency got changed. I never heard a 'click' when a frequency is changed. I noticed the Controller's voice sounded somewhat different; but assumed there had been a controller change. At all times during the event we had visual contact with the other aircraft in the area and we did not receive a TCAS alert. Inadvertently changing an approach frequency during a critical time is an error that occurred during this event. This error led to the aircraft not being at its expected location on final approach. Fortunately; we were able to maintain visual separation with other aircraft and continue the approach uneventfully. Being that I can't determine how the frequency got changed when it did; I'm not sure there is a solution to prevent this event from happening. It's an error that could happen to anyone.


Second narrative: We had been handed off and checked in with the second Approach Controller in ATL and had received a vector to turn 360; expecting another turn for the visual approach to Runway 28 in ATL. ATC identified our traffic and we replied we had it in sight. We were on a perpendicular course to final. We did not receive instructions to turn to join; so the Captain inquired as soon as radio traffic allowed. We maintained visual separation with the traffic and were close to the final approach course with a 90 degree intercept at that point. ATC immediately gave us a turn to the southwest. We complied with the instructions as we overshot the localizer course for Runway 28 and encroached on the approach airspace for Runway 27L. We were then told that we were on the wrong frequency and given the correct frequency. We checked in with final Approach Control for Runway 28; and were cleared for the visual approach. The rest of the approach and landing were uneventful.Somehow; while being vectored to final; the frequency got changed from the final Approach Controller to the initial Approach Controller. I do not know how the frequency got changed. At all times during the event we had visual contact with the other aircraft in the area and we did not receive a TCAS alert. This error led to a momentary loss of communication with the correct controller. This led to the aircraft crossing through the final approach course momentarily. However; we were able to maintain situational awareness; visual separation with other aircraft and we were able reestablish communication with the correct controller and continue the approach uneventfully. Being unable to determine how the frequency got changed when it did; I'm not sure what the solution is to prevent this event from happening. I've never had this error happen before situational awareness and querying ATC was the key to a successful correction of the error.


Synopsis: CRJ700 flight crew reports an inadvertent frequency change during approach causing a localizer overshoot before communication can be reestablished. See ACN 1105166.