Setting Up Radios

[rddaos]

I'm currently working through some tutorials on setting up radios, and I have 3 major questions:

1. Why there are two different COM radios (COM 1 & COM 2) each with an active and standby frequency (a total of 4 frequencies)? Why not just use a single COM radio with a single frequency and switch the frequency as needed?  Or better yet, why not have 10 COM radios, if more is better?

2. My understanding is that the NAV radios exist so that aircraft instruments (e.g. ADF) may recieve signals from waypoint beacons, while the COM radios exist so that the pilot can have conversations with humans (e.g. air traffic control). Is this the correct distinction between the two categories of radio?

3. Is it only necessary to manually switch between waypoint frequencies when flying by hand? In other words, if the autopilot is engaged, and each waypoint has already been fed into the FMS, is there any need to fiddle with the NAV radios along the way?

Thanks guys!

[LA]

There are several advantages for having two comm radios. If a comm fails, it's great to have an easy and accessible backup. In my case (real life), I'll have three or four frequencies in use at the same time. When flying with several other aircraft, I'll use one for the airport I just left. Another frequency is for ATC, as I'm flying under Class B airspace. I might not be talking to them, but at least I'm aware of whats going on around me. The third frequency is for air to air, with the other airplanes in our group.

Another situation is where I fly around a point of the mountain that has an untowered airport on each side. One radio is set for one airport, and again ATC, as we're under the veil of Class B.

The second radio is set for the destination airport's unicom frequency, and it's AWOS. Sure you can do all this with one comm, and the flip/flop frequencies make it easier. But two comms managed through an audio panel make it even more convienient.

As for nav radios and auto-pilots (FMC. etc) , my plane is GPS auto-pilot coupled. I don't have NAV radios. My auto-pilot will fly from any waypoint I select, to the next & the next, automatically. Mine isn't legal for IFR, though

LA

[garrettm30]

Answer to # 2: Your understanding is correct.

Answer to # 3: For flying purposes, you don't need to enter waypoint frequencies in the nav radios if your are operating under the control of the FMS. The FMS does not use radio signal. It is essentially GPS (and maybe inertial?). However, you do need to enter a frequency for ILS when nearing final, even while FMS is still your source for the flight director until ILS intercept. Further, you should have tuned in things like fix and course for missed approach procedures, etc. Essentially, when you are flying with FMS, you still have the nav radios ready to go if you have to switch over to them. And if ATC tells you to hold, likely it will be radio fix. So they won't be working at the same time, but you do keep the radios ready. Did I make that clear enough?

As a side note, I often prefer to fly by the radios when on autopilot rather than the FMS. Otherwise, the en-route phase of flight is just too boring. I have learned a lot about navigation in this way.

Edit: Nav radios aren't just for flying by hand. You can have autopilot set to either the radios or the FMS for its source, but it is autopilot either way.