Whining on frequency?
 

Hi,


Something I've long wondered is why some aircraft's radio transmissions carry with them a distinctive whine?

Its far less common that it once was - but it was very noticeable when a certain Nordic operator's MD82 came on frequency the other day - kind of took me back to the 1980s !

What is it? is it a fault that has developed? or is it a property of poor voltage regulation and bad design on some radios?

Cheers

And there I was thinking you were talking about pilots!!!!:E

That would be Aussie pilots then:rolleyes:

Funny our cabin crew complain about the same thing.:E

Probably the 'certain nordic airline' 's pilots prefer using the hand mike, which picks up more background noise, to wearing a headset.

I seem to remember a certain nordic airline being criticized for not hearing ATC transmissions (in connection with a TCAS RA report, if memory serves) for the same reason. It was recommended that they use headsets.

Some of our pilots whine more than the engines.

This used to be a common problem with Ansett and I believe that Qantas still experience it.

The ex-pat Engineers tried to troubleshoot it but could never reproduce it although our Aussie colleagues had it every time.

It remained one of lifes great mysteries.:rolleyes:

I believe it was more of an Ansett problem if memory serves me right, strange how it was only apparent with local crews and engineers:rolleyes:

But at least the Ansett and Qantas engineers were up to the task of sorting the problem.

Sounds like poor filtering - interference from another transmitter on a nearby frequency..

The whine you hear is probably right at 400hz, one can hear it in many birds, it is the same frequency as the aircraft's AC systems. The bulk of the electrical power used on the aircraft is of this frequency, so it can be expected to bleed through from time to time. You can hear the identical noise standing next to a jetway power supply - also 400hz. One also notices that its never heard from small, piston aircraft with an exclusively DC electrical system. Lots of other squeals and scratchiness, but never the 400hz hum.

We used to get it on our first A320's but only when giving OJT to engineers from a certain now defunct Aussie airline.:rolleyes: