[TowerTalk] Rain static

[Dennis O'Connor]

We have beat this particular horse to insensibility in the past on this forum...  As soon as I saw the first posting I knew that Tom would chime in...  Let me add a factoid...
Numerous times in flying I have flown through precip that causes severe static in the COM radios (aircraft com radios are VHF AM), such as rain and snow,... I have also read reports of air tankers having static problems flying in heavy smoke over forest fires... 

The worst I precip static was ever in was flying across Lake Erie one night from Cleveland towards Detroit in 18-20 F degree temps and heavy snow...  I was flying my Super Viking which has wood wings and a steel tube fuselage with a dacron fabric cover...  We were doing 180 mph through the air...
The static charge built up on the airframe surface until it began to arc across various parts of the airframe (probably from the wing surface to the steel frame of the fuselage at exposed bolts, etc.)
It would begin as a sharp "tick" in the headphones... The tick would be perhaps once a second, then  increase in frequency until it was like a machine gun, then start elevating in pitch until it became a mixed howling / roaring sound that obliterated all communications... From just before the machine gun stage onwards I could not hear air traffic control... Then there would be an enormous 'bang' followed by complete silence during which I could get a 5 - 10 second transmission from ATC, by then the tick, tick restarted...  The whole cycle would take from 30 to 60 seconds...
The interesting part is that as I flew in and out of the snow showers, there was not a trace of static when I was out of the snow...  As soon as the snow thickened in the windscreen it would promptly start ticking again...  

denny