What is the use of COM and NAV in an aircraft?

Question

I am sorry if my questions are sometimes wage, I am totally new in this field.

I know com stands for Communication and Nav stands for Navigation. I want to know exactly when I push comm.1 or comm.2 button what will happens? and the same for navigation.

By pushing comm button, I can listen only to the radio? which one connects me to the ground unit?

Answer 1

Depends on how your audio panel is set up in the aircraft you are in.

Some allow you to listen to only one device at a time. Others offer a lot more versatility.

In my plane for example, there is a k**b that will move between Com 1 and Com 2, the two Nav/Com radios installed in the panel. Switching between the two allows me to listen and talk on the selected radio. There are however buttons on the audio panel that will also allow me to additionally monitor the other Com radio from the one the k**b has selected, or monitor either Nav frequency that is tuned on either radio or other receivers such as NDB, Marker Beacon, etc. In that manner you could for example be on with Approach or a Tower frequency on your selected radio and still monitor the ATIS frequency, a VOR, the marker beacons, etc.

Answer 2

As other people have mentioned, audio panels vary. Typically, you will have two navigation radios and two communication radios. If you were always listening to every radio, you'd be constantly bombarded with junk. So the audio panel provides you a way to select what you're listening to and what you're talking to.

Starting with the communication radios, you usually have a primary selector and a monitor button for each radio. The primary selector allows you to listen to a radio and select which radio you would transmit on if you pushed the 'push to talk' button. This is probably your most frequently used button. If you're using com1 to talk to ground control and have com2 set for the tower frequency, you would push the selector for com2 to switch to talking and listening on com2 instead of com1.

There's usually a monitor button that allows you to listen to a com radio without changing which one you talk on. You might be talking to air traffic control on com2 and have com1 set to the terminal information frequency for an airport you plan to land it. You might push the com1 monitor button for a few seconds to check if you are in range of the terminal information broadcast.

As for the navigation radios, you usually only need to listen to them in certain circumstances. Probably the most common is to identify a navigational aid. If you have, say, nav1 tuned to a VOR, you may want to make sure it is actually receiving that VOR and that the VOR is operational. The way to do this would be to push the nav1 monitor button and listen. The VOR will transmit an identification code (its identifier in morse code, also indicated as dots and dashes on approach plates, sectional charts, and the like). This allows you to confirm that you are strongly receiving the correct signal. You can't transmit on navigation radios, so there's only a monitor button.

Again, audio layouts and panel capabilities vary. However, the basic setup of two navigation radios, two communication radios, and a way to monitor any combination of them, is present on the majority of aircraft.

Answer 3

Sounds like you are describing the selector buttons on the audio panel.  These select the source of audio signal for the speakers or headphones.

Don't know exactly what you mean by the "ground unit."  With a typical audio panel, you have a miniature toggle switch or a push on/push off button for each device.  Push "comm1" to connect the audio output of the #1 comm radio to your headphones or "comm2" to connect to the #2 comm radio.

The features of these audio panels vary; some include additional devices like Marker Beacon receivers.

If you need to understand more, ask your instructor to explain the audio panel to you.

Good luck!