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McDonnell Douglas PA system

Posted: Tue May 19, 2020 8:00 pm
by PhotographyNYC
Whenever I fly on a MD-80 or 88 or 90 (especially delta) whenever the intercom system is in use there’s A continuous whiny sound in the background, what is that, and why is it only on MD airplanes?

Re: McDonnell Douglas PA system

Posted: Tue May 19, 2020 9:42 pm
by CoronadoConrad
Interference from the 400Hz AC system, aircraft with better shielding/filtering might not make this sound over the PA.