Regional Jet 900 (CRJ900)
Flight Crew Air Transport Pilot (ATP)
Distraction; Communication Breakdown
Aircraft Equipment Problem Less Severe
Flight Crew FLC Overrode Automation
Human Factors; Aircraft
During the initial climb of the flight we experience 9 events of strong radio interference due to ACARS transmissions/crosstalk. These events caused both discomfort due to the very loud volume of the interfering transmissions and difficulty in understanding ATC communication.  We followed the temporary procedure issued recently by the company and switched the COMM 3 radio from 'DATA' to 'VOICE' disabling ACARS communications. Above FL180 we reactivated ACARS communications and there was right away 2 more events of interference. During the last eight weeks many crews have been experiencing frequent events of radio interference due to ACARS transmissions/crosstalk. These interference events should be a safety concern. They caused in more than one occasion to miss/misunderstand critical ATC communications and instructions during the departure phase of the flight. Last week the company has finally made available a temporary mitigation procedure but did not notify the pilot group about it. Some of the airplanes in our fleet do not have the COMM 3 VOICE/DATA button which allow to disable the ACARS system as recommended by the temporary procedure.Root cause: Something changed since December 2013. The interference could be caused by changes in the ACARS communication software; protocols; procedures; equipment. Usually after Weight off Wheel both the FMS and the EICAS show an 'ACARS NO COMM' message; shortly after that a very loud burst of digital communication is heard into the pilot headsets. In the worst cases the interfering signal is repeated multiple times during the first few minutes after takeoff. There should be an investigation of these events. Only last week; 8 weeks after the beginning of the interference problems the airline has finally provided pilots with a mitigation procedure for the interference problems. The procedure is not applicable on some of the airplanes in our fleet because they do not have a COMM 3 VOICE/DATA button which allows to disable ACARS system communications. It is also true that they never notified the pilots about the issue nor of the availability of the mitigation procedure.
CRJ900 First Officer reports strong VHF radio interference when the ACARS transmits data on VHF 3 after takeoff. Switching VHF3 to voice will stop the data transmission but not all aircraft have this switch.