Narrative:

The pilots report a constant squeal or static on frequency 120.0 from the moment they dial in the numbers and switch on the radio. This occurs while they monitor the frequency and they always ask to switch to another available frequency because the interference is too much. The controllers in the tower never hear the noise. The interference is in the aircraft. The only optional frequency to switch these aircraft to is the ground control frequency 121.9. A potential unsafe condition arises every time we switch these aircraft to another controller's frequency. This happens too often. Supplemental information from acn 226604: continuous side tone, reported to sound like a stuck microphone by air crews. Problem at time believed to be associated with antenna location for ACARS system on aircraft. Noise very distracting on final and a potential associated distraction in a deteriorated environment. Callback conversation with reporter revealed the following information: the planning procedure specialist was called to see if any solution to the frequency problem was forthcoming. Analyst was referred to facility manager who had been investigating the problem. Facility manager stated the problem was found to be with aircraft equipment radio. Cpr aircraft are now having same problem. Other ATC facilities are also having problem. The interference only involves frequencys ending with decimal 0 (120.0, 118.0, 119.0, etc). Manager stated he had been contacted by an air carrier company which looked into the problem and said it was caused by ACARS symbol generator in the aircraft. FAA region and washington are aware of problem.

Related reports:

Google
 

Original NASA ASRS Text

Title: ACR AND CPR ACFT WITH ACARS EQUIP RECEIVE INTERFERENCE ON LCL CTL FREQ 120 PT 0. ACFT EQUIP PROBLEM RADIO.

Narrative: THE PLTS RPT A CONSTANT SQUEAL OR STATIC ON FREQ 120.0 FROM THE MOMENT THEY DIAL IN THE NUMBERS AND SWITCH ON THE RADIO. THIS OCCURS WHILE THEY MONITOR THE FREQ AND THEY ALWAYS ASK TO SWITCH TO ANOTHER AVAILABLE FREQ BECAUSE THE INTERFERENCE IS TOO MUCH. THE CTLRS IN THE TWR NEVER HEAR THE NOISE. THE INTERFERENCE IS IN THE ACFT. THE ONLY OPTIONAL FREQ TO SWITCH THESE ACFT TO IS THE GND CTL FREQ 121.9. A POTENTIAL UNSAFE CONDITION ARISES EVERY TIME WE SWITCH THESE ACFT TO ANOTHER CTLR'S FREQ. THIS HAPPENS TOO OFTEN. SUPPLEMENTAL INFO FROM ACN 226604: CONTINUOUS SIDE TONE, RPTED TO SOUND LIKE A STUCK MIKE BY AIR CREWS. PROBLEM AT TIME BELIEVED TO BE ASSOCIATED WITH ANTENNA LOCATION FOR ACARS SYS ON ACFT. NOISE VERY DISTRACTING ON FINAL AND A POTENTIAL ASSOCIATED DISTR IN A DETERIORATED ENVIRONMENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE PLANNING PROC SPECIALIST WAS CALLED TO SEE IF ANY SOLUTION TO THE FREQ PROBLEM WAS FORTHCOMING. ANALYST WAS REFERRED TO FACILITY MGR WHO HAD BEEN INVESTIGATING THE PROBLEM. FACILITY MGR STATED THE PROBLEM WAS FOUND TO BE WITH ACFT EQUIP RADIO. CPR ACFT ARE NOW HAVING SAME PROBLEM. OTHER ATC FACILITIES ARE ALSO HAVING PROBLEM. THE INTERFERENCE ONLY INVOLVES FREQS ENDING WITH DECIMAL 0 (120.0, 118.0, 119.0, ETC). MGR STATED HE HAD BEEN CONTACTED BY AN ACR COMPANY WHICH LOOKED INTO THE PROBLEM AND SAID IT WAS CAUSED BY ACARS SYMBOL GENERATOR IN THE ACFT. FAA REGION AND WASHINGTON ARE AWARE OF PROBLEM.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.