RadioBanter - View Single Post

May 2nd 04, 10:47 AM

(Jim) wrote in message . com...
All jokes aside, it is interesting to note that ATC were talking to
Royal Dutch Airlines on that frequency. I guess aircrafts have VHF as
well as HF radios onboard.

Sure. Many airliners have at least two HF radios, "one a backup", and
at least two or more VHF. That they were talking to Nairobi doesn't
necessarily mean they were flying there, or even flying over Africa,
although they may well have been. In general, the HF radios are not
ATC in the narrow sense. ATC is what is on VHF in general. IE:
departure, approach, tower freq's, etc...The HF radio you hear are
private companies that *sell* their services to the airlines. The time
of day, propagation, and signal quality, etc, will determine what
cities "radio" they use, more than destination, or flight path. This
will also determine the freq's used, and the backups. The backups will
usually be a lower freq than the main assigned freq, if they advise
them to stick around for calls. Again , purely propagation
related...Many cities have these aviation radio service companies.
There is one here in Houston. "Houston Universal Radio". They have a
web site. You can listen to them on 17.965,13.330, 10.075,6.637,
etc...10 and 13 probably the most active in the day...You won't hear
them working many planes flying to Texas, or Houston. They are usually
working ones quite a ways off, but depends on the freq. They do get
some route info, etc, which I guess could be called ATC in a way, but
it's more for company use than ATC, unless they are over the oceans
maybe...I suspect usable VHF "center" freq's are kind of scarce over
the atlantic...:/ They use it to talk to the dispatchers, get updated
wx, complain about stuff breaking, get sel-call checks, etc...Of
course, they do a lot of that with ACARS now...But when you hear them
talking on HF, they are paying for that service, and they can use
other cities services if they want, and their company does biz with
that particular radio co. The actual ATC on VHF is gov supplied and
paid for...The airlines don't pay for it, as neither do private
pilots. You can hear cities with HF aviation radio co's all over the
world. London, Tokyo, San Francisco, Houston, Miami, NY, Iowa,
Johannasburg, Honolulu, .heck, you name it nearly...You can nearly
make a SWL career just listening to HF aircraft services...:/ Heck, I
wouldn't be surprised if a few haven't sent out QSL cards
before...After all, they like signal reports same as SWBC'ers. Most
run multiple freqs, and I suspect use monster "all band" log periodic
beams, etc...About like the offshore oil company HF radio setups...
MK