:
: >I bought this handheld Uniden Bearcat BC120XLT to listen to aviation
: >communication between air traffic controllers (ATC) and airplane pilots. The
: >problem I'm having is that I can only hear airplane pilots chat but I don't
: >hear any air traffic controllers. When I scan the local airport frequencies
: >(approach, tower, departure, ground, center, clearance, atis) I get a fairly
: >clear reception of airplane pilot communications but I don't hear the ATC.
: >
: >Is this a weakness of my handheld BC120XLT scanner?
:
: Nope.
:
: >Am I not supposed to hear both the airplane pilots and ATC?
:
: Often you will not hear ATC or Unicom even when you're on the ground
: only a mile or two from the airport.
:
: >BTW, I live at about 8 miles from a major international airport (MIA) and
: >about 2 miles from an fairly active executive & training airport (TMB).
:
: That's far enough...
:
: Aircraft communications is a line of sight business. I believe the
: antennas on ground stations are designed so very little of the RF
: stays near the ground. After all, it simply wouldn't do to have an
: aircraft directly overhead unable to maintain contact with ATC.
Keep in mind as well, the higher the transmitting antenna, the longer the
reception distance.
Take a standard 3 inch post-it note and call it the coverage area of the
tower antenna at ground level. Now stick it to the 50 yard line of a
football field, and call the stadium the coverage area of the airplane.
That give you any idea of the comparison? :)
That's one of the reasons (so I'm told, and it makes good sense - better
than the lame one about screwing up avionics, at least) that you aren't
allowed to use a cell-phone on an airplane in flight. Instead of hitting
one or two cell towers, you might end up hitting 50, since the "footprint"
of your signal is so gawd-awful huge compared to what it would be on the
ground. A situation like that would likely SNAFU the cell towers in a big
way...
--
Horseman by day, 'net-freak by night. What a contrast, eh?
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