Date: 201403
Local time of day: 1201-1800
Location: ZOB.ARTCC, OH
Flight conditions: VMC
Light: Daylight
Aircraft: Regional Jet 900 (CRJ900)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Climb
Airspace: Class A ZOB
ATC / advisory: Center ZOB
Aircraft component: ACARS
Component problem: Design
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Human-Machine Interface; Communication Breakdown; Troubleshooting
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Contributing factors: Aircraft; Company Policy; Human Factors
Primary problem: Aircraft

Narrative: During the initial climb of the flight we experienced 7 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; one more event 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 have caused flight crews--on more than one occasion--to miss/misunderstand critical ATC communications and clearances during the departure phase of flights. Last week the company finally made available a temporary mitigation procedure but did not notify the pilot group about it. Something has changed in the last few months to generate this problem. The interference could be caused by changes in the ACARS communication software; protocols; procedures or equipment. Usually; after Weight off Wheels; 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 worse 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; eight weeks after the beginning of the interference problems; the airline finally provided pilots with a mitigation procedure for the interference problems. The procedure; however; is not applicable on some of the airplanes in our fleet because they do not have the COMM 3 VOICE/DATA button which allows crews to disable ACARS system communications. It is also true that the company never notified the pilots about the issue nor of the availability of the mitigation procedure. Our airline's inability to listen and communicate in a timely fashion with flight crews about safety issues like this should be; on its own; a serious safety concern.




Synopsis: A CRJ-900 First Officer reported repeated and strong VHF COM interference episodes that have been determined to be the result of ACARS data transmissions. The reporter declares the events to be at a very high volume and disruptive of communications with ATC. A procedure found to mitigate the interference was developed but not adequately distributed to the pilot group. In addition; the means by which the procedure is implemented--a switch to select 'ACARS' or 'COMM' functionality on the number three VHF transceiver--is not installed on all the company's adversely affected fleet.