Frank wrote:
David Casey ...

^ Do aircraft and folks on the ground talk to each other on
^ 2 different frequencies?

It is common with flight service stations. The FSS transmits on 122.0 and the
pilot may be required to transmit on 122.1.

Frank


Actually in cases where "duplexed" is used for FSS FSS at those times
transmits via a VOR (108-118 MHz) that is close to the plane. The pilot
will tune his COM radio to 122.0, 122.1 or what ever other frequency is
is listed on the sectional above the VOR's information block. The pilot
whould then transmit on that frequency.

FSS would receive the pilot on 122.0, 122.1 etc. The pilot however
would turn up the volumn on his NAV radio and have it tuned to closest
VOR to his location, FSS would be transmitting through the VOR on the
VOR's frequency via a dedicated phone line link.

Great example where I have actual experience with this was when I was
living and flying out of the Lancaster, PA area. The Lancaster VOR
freq (LRP) is 117.3 MHz however FSS was to far away (located in
Williamsport, PA) to be heard by an aircraft at low altitudes. However
since the plane was flying at 1,000' or higher FSS could receive my
signal on 122.0 however I would be two far away to hear FSS's reply on
122.0 so I would be listening for the reply on 117.3 as the Lancaster
VOR was only a few miles away where has FSS in Williamsport was about
100 miles away.

Now so FSS actually knows that you're expecting them to reply on a VOR
freq instead of direct on 122.0 here is how you would make your radio
call "Williamsport Radio, Cherokee 9335W receiving Lancaster VOR".

George
http://www.MilAirComms.com