User Guide

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TRANSPONDER
While the transponder doesn’t tell you a whole lot, it tells
the world around you - specifically, air traffic controllers - some
things it’s very important for them to know.
Specifically, it tells the rest of the world two things: who you
are, by the numerical code you set into it; and, since ATC’s radars
see in only two dimensions, how high you are, by electronic
information it gets from your altimeter and transmits to the ground
radars every time they sweep past you (and “interrogate” your
transponder, if you want a fancy technical buzzword).
Its controls are very simple. Transponder codes consist of
four digits, from 0000 (which is never used) to 7777 (also never
used); the archaic computer brains of the FAA can’t recognize any
digit larger than 7. When you’re assigned a specific code by ATC
(typically, as part of an instrument clearance or during a conver-
sation with a controller when you want to enter controlled air-
space), just punch it in using the buttons. The “CLR” key can be
considered a “backspace” if you make a mistake.
Of course, often you’ll be flying in visual conditions without
talking to any controllers at all. There’s a standard VFR transponder
code for this, 1200 - and rather than having to punch it in every
time, just hit the “VFR” button and it’ll be set automatically. Often,
the first time you talk to a controller, you’ll be using this code, and
to help pick you out from all the other VFR traffic, he or she will ask
you to “squawk ident.” This makes your blip light up specially on
the screen; to do it, just hit the “IDT” button (which, despite what
your instructor may say, does not stand for “idiot”).
Finally, there’s the big mode selector switch on the right side
of the unit. The “OFF” position - surprise, surprise! - turns the whole
thing off altogether. “SBY” is a standby mode, in which the unit is
powered up but not responding to interrogations. It’s considered
Want to know your bearing “TO” the VOR station without all
that laborious OBS-knob twiddling? Push the mode button again,
and the standby frequency display will change to your current bear-
ing, complete with the word “TO.” Another push and the same
thing happens, except now you see the radial, and, appropriately
enough, the word “FROM.” In either of these modes, if the signal is
too weak, the display changes to a line of dashes.
Another push of the mode button gets you a very fancy stop-
watch, which starts counting up as soon as you enter this mode.
To stop it and reset it to zero, hold the frequency transfer button
for a couple of seconds. Subsequent pushes on the transfer button
start and stop the stopwatch.
But wait! There’s more! When you’ve reset the stopwatch to
zero, you can use the frequency knobs to preset times and use it
as a countdown timer, very handy for instrument approaches.
Left/Right click the knob to change minutes. Double click the
knob to toggle minutes and seconds. Left/Right click the knob to
change seconds. Now, pushing the frequency transfer button will
start the timer counting down from the preset value.
A final push of the mode button gets you back to the basic
frequency-select mode. The stopwatch, if running, will keep on
doing so; you can refer back to it any time with four quick push-
es on the mode button. Since both the #1 and #2 nav-comm
radios have this feature, you have two separate stopwatches at
your disposal - for example, one might be monitoring how long
it’s been since you took off, while the other might be counting
down to remind you to switch fuel tanks later on.
Flight Instruction
Flight Instruction