What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Use cases for dual-COMM ?

H

humptybump

Well Known Member
I am looking for first hand use cases where having two COMM radios is better than having one COMM with "monitor" capability.
 
I have an SL-30 and an SL-40. I seldom fly into towered airports. I set local and destination CTAFs in the first, and ASOS/AWOS in the second. Just makes it easy for me. I do not use the monitor functions in either.
 
Flying IFR or out of our Charlie airspace airport it is nice but is something I could do without if necessary. Less workload if you can keep Approach Control and tower in the primary with ground and ATIS in the secondary.
 
ATIS/Tower/Ground freqs in the secondary with ATC in the primary. I fly a lot of cross country in the system so this works for me. Plus, on the odd occasion I want to talk to Flight Watch, it helps to have the secondary com
 
Once you have dual comms, you can never go back. I always have the #2 radio on the next expected contact frequency. With flip-flops on 2 radios you always have 4 frequencies at the ready.

I also monitor 121.5 on #2 while enroute.
 
Last edited:
Back when I flew a Mooney IFR everywhere with two comms it was great for the convenience but, frankly, the biggest nicety was being able to monitor one freq while talking to ATC on the other. Having four at the ready like Mel said was nice but with the integrated EFIS capabilities of "point and click" tuning I'm not sure that is as needed as before.

So, if I was outfitting a panel for IFR I"d probably really want two comms BUT if it was a choice of spending that dough for a second com versus better EFIS/moving map capability I"d go that route as long as the comm could monitor a second freq.

Make sense?
 
Last edited:
Dual comms

I can't imagine flying IFR without dual comms. It can be done but it wouldn't be fun. You need the second comm to check ATIS, weather, etc. without having to ask for permission to leave the frequency.
 
Lote said:
I can't imagine flying IFR without dual comms. It can be done but it wouldn't be fun. You need the second comm to check ATIS, weather, etc. without having to ask for permission to leave the frequency.
Click to expand...

Interesting. I always asked to leave even if I could monitor since I was worried about missing a call while I was talking. Found it to be a non-event.
 
Agreed, once you have it you'll never go back. It's just too darn useful to not install.
 
The downside of relying on the "monitor" function of the Garmin SL30/40 is that in busy airspace (where I often fly) you may have to "monitor" the ATIS/ASOS for a very long time to get all the info since it cuts out with every radio call on the primary freq.
 
The other advantage is redundancy.

Even as a VFR flier only you usually need comms. on a long trip. A single radio failure will not affect your trip if your second "monitoring" function is also a transmitter.

Go for two Tx/Rx units.
 
I'm based at a towered field and if I had a radio failure, it would be a major pain to get back in. Assuming murphys law will come into play, the com would fail when I was running late coming home one day and landing somewhere else to call tower, etc. would make me really late and so on. Besides that all these other posts made the other arguments for convenience I would have made.
 
You should also be monitoring 121.5 at all times. It can save you from a potential flight violation among other issues.

George
 
On top of dual com (sometimes I wish I had a third radio), we use Split-Com quite a bit. Left seat on com1, right seat on com2, both doing separate business, not just listening, but transmitting at the same time.
 
Try leading a large, or any size, formation in or out of a controlled field and it's worth it.
Agree with others who say, once you use two, you want two..
 
I have a single com radio with the standby frequency monitor function, but panel space is at a premium in my tight cockpit. If I could fit two, I would. Monitor functions by default have to prioritise reception so your primary or "more important" frequency needs to be relatively quiet for you to make sense of what is happening on the standby. That just isn't realistic in many scenarios.

I've been brought up on managing two comm radios in my day job and found the transition back to a single in my leisure time to be a bit of a PITA, even when operating in uncontrolled airspace.
 
Two coms is a really nice feature to have especially if you fly IFR. I only have a single com, SL30, and find it more than adequite. That said I also have a second antenna on my belly and access to the connector under the panel so it can easily hook up to my handheld with the adapter should my SL30 crash. I always fly with my HH on XC's.
 
Going to buck the trend here. I'm limited to VFR, but have never felt the need for two comms. I see that the original poster is also VFR.. My tiny brain can only listen or talk to one thing at a time so the SL40 with monitor suits me just fine. If you feel the need for quick access to more frequencies you can always use the preset memories, but frankly I don't bother and instead just plan ahead and tune in what I will need next on the standby/monitor side. Have never felt so rushed that I just couldn't live without a 2nd comm.

Redundancy is certainly a valid concern, but my sl40 has been rock solid and I carry a hand held as a back up for my longer flights. You can plan your wiring so that you can plug it right into your external antenna if needed, and of course into your headset as well. Haven't yet needed it as a backup, but do occasionally use it outside the plane as a true hand held, so good value there i figure.

May well have a different opinion if I was IFR and/or had more money, but Im flying and happy about that.
erich
 
I fly day VFR. I have single radio with monitor function and have never wished I had a second radio. The country is littered with cool little airports to land at and get gas and food that do not even require a radio to go visit. YMMV but that is the flying I do and love.
 
I appreciate the diversity of use cases. I couldn't have asked for nicer people or so many different responses - Thanks!

All things being equal - aka cost, install, panel space, etc. - I would not have asked this question. A second comm is every so handy. But, all things are not equal. With radios like the GTR-200 and it's competition, the single comm setup has one antenna, one radio, and can easily be used as the intercom and service the inputs for basic audio alerts from multiple devices (EFIS, AP, EMS, AOA, etc).

So the adding of a second comm means locating a second antenna and adding an audio panel.

I already have the audio panel so the added cost is really the second radio+antenna+figuring out the antenna placement (on a flying aircraft). The cost also includes any income from selling the used audio panel.

To Erich's comment - yes, the plane is VFR day/night today. I'm instrument rated and the plane will be suitably equipped the next time I cave to working on the panel.

I didn't want to give all that information because I really wanted people to share how and when the use the second comm. THANKS!
 
humptybump said:
So the adding of a second comm means locating a second antenna and adding an audio panel.
Click to expand...

If you have an intercom with unswitched inputs, you may not need an audio panel, just a switch to move the mike and PTT lines. Depends on your needs and desires.
 
An audio panel is not required for dual com radios. My -6 has been flying for over 21 years with dual coms and no audio panel.
 
One or two

I had a Nav **** out 2 miles from the COS LOM. Nice time for really good backup already set. With a threat of a missed approach, a second NAV set for the initial missed approach segment is really handy. I lost COM on another IFR flight over the continental divide. It sure is lonely without communication and navigation. On the other hand, my recollection is that T38's had only had one NAVCOM. Go figure!
 
With two pilots, they can each talk on a different radio. Handy when one is on with ATC and the other is calling Unicom for a rental car or whatever. Or one is talking to FSS while one is on with ATC.
Of course it doesn't happen often, but it's nice when it does.
 
jnmeade said:
With two pilots, they can each talk on a different radio. Handy when one is on with ATC and the other is calling Unicom for a rental car or whatever. Or one is talking to FSS while one is on with ATC.
Of course it doesn't happen often, but it's nice when it does.
Click to expand...

It just depends. It happens all the time in our world :). A comfortable way to roll :).
 
I don't generally like to disagree on this forum and stick my nose in too often but this is one topic that just gets to me. A few of you nice folks are stating that for VFR only 1 com is needed. We as pilots go through so much to make our planes safe to fly and redundant if possible ( I know we all fly single engines for the most part so redundant engines are not an option on RVs . . . at least I haven't seen a twin RV yet ), but why would you not want to add redundancy for 1 or even 2 of the 3 pillars of flying? Remember, Aviate, Navigate and communicate. Too many people fly in these uncontrolled/non-towered fields with no radios stating that communications are not required !!!! I will never understand why someone would fly in to a public field and not listen for other traffic or notices at the airport. You know, its NOT required to have to have 2 Magnetos either but most of us who have Mags, have 2 . . .

If you decide to go with just 1, at least carry a hand held in case you lose your radio, it may safe your life one day.
 
BCP Boys said:
I don't generally like to disagree on this forum and stick my nose in too often but this is one topic that just gets to me. A few of you nice folks are stating that for VFR only 1 com is needed. We as pilots go through so much to make our planes safe to fly and redundant if possible ( I know we all fly single engines for the most part so redundant engines are not an option on RVs . . . at least I haven't seen a twin RV yet ), but why would you not want to add redundancy for 1 or even 2 of the 3 pillars of flying? Remember, Aviate, Navigate and communicate. Too many people fly in these uncontrolled/non-towered fields with no radios stating that communications are not required !!!! I will never understand why someone would fly in to a public field and not listen for other traffic or notices at the airport. You know, its NOT required to have to have 2 Magnetos either but most of us who have Mags, have 2 . . .

If you decide to go with just 1, at least carry a hand held in case you lose your radio, it may safe your life one day.
Click to expand...

With current solid state electronics, how often do radios fail?

I fly almost every week with no radio airplanes in the pattern. Yes, they do weird stuff but if you are doing, as taught, to look outside, they are little more inconvenient then some one using a radio. Your experience may vary depending on how busy the airport is.

The saying "aviate, navigate, communicate" is to remind you that communications is not at the top of the list, not to say it is required (or a pillar of flying)

Opinions may vary depending on your experience. I do not fly much to towered airport and have lots of experience with no radio planes. That definitely sets my experience (opinion).
 
Last edited:
This may not apply to everyone but certainly where I come from, not flying to towered airports is not an excuse to not have a VHF com.

Maybe other countries are different, but not having a radio (and using it) for broadcasts here at non-towered airports does have the potential to get you in a lot of strife, both from a safety perspective and a regulatory perspective. We have the accident record to prove it. And as is often the case, bits of a plane showering down on someone's home can prompt the regulators to step in.
 
Pilot activated lighting

humptybump said:
yes, the plane is VFR day/night today.
Click to expand...

If you fly at night (VFR or IFR) then you will ultimately need to switch on pilot activated lighting (PAL) at some airfields. If your single radio fails to transmit then you may be left circling around in the dark contemplating your options....not good.
 
Do I need two coms?

I guess it depends on how you were trained. I flew the T-38A Talon for seven years, and it had one 120VAC, 3 phase, UHF com. Just before I left the Air Force, new DC solid state UHF radios were being installed. The old radios were a fifty pound box filled with vacuum tubes up in the nose. I think they were left over from WWII. They failed all the time, and IP's and students alike got very good at radio out procedures.

If IFR:
1) Sq 7600
2) Proceed to your clearance limit, and then at you EAC, proceed as filed
3) Shoot the approach and land

If VFR:
1) Proceed to the VFR entry point
2) Enter the pattern on the outside downwind
3) Rock wings on initial
4) Pitch out and land

NO Big Deal

I'd like to add that a T-38 sortie averaged 1.3 and landed with 600 lbs of JP-4 remaining, or about ten minutes of fuel. Best glide speed engine out, with zero fuel remaining was 230K. You couldn't just land it anywhere like we can our RVs. Of course, it did have aircraft jettison handles on each side of the seat!

IMHO it is not reckless to have a single Nav/Com or a single engine. If your budget, or panel space is a factor, buy one good radio! The Doll has one incredible GTN 650. For the last 14 years, radio out procedures have not been required!
 
Last edited:
BCP Boys said:
I don't generally like to disagree on this forum and stick my nose in too often but this is one topic that just gets to me. A few of you nice folks are stating that for VFR only 1 com is needed. We as pilots go through so much to make our planes safe to fly and redundant if possible ( I know we all fly single engines for the most part so redundant engines are not an option on RVs . . . at least I haven't seen a twin RV yet ), but why would you not want to add redundancy for 1 or even 2 of the 3 pillars of flying? Remember, Aviate, Navigate and communicate. Too many people fly in these uncontrolled/non-towered fields with no radios stating that communications are not required !!!! I will never understand why someone would fly in to a public field and not listen for other traffic or notices at the airport. You know, its NOT required to have to have 2 Magnetos either but most of us who have Mags, have 2 . . .

If you decide to go with just 1, at least carry a hand held in case you lose your radio, it may safe your life one day.
Click to expand...
I rarely, more like never, fly anywhere that loss of com will cause a life threatening condition. Not even close. And I fly lots of places. Light IFR, grass strips, Bravo airspace, etc.
 
Hi everyone, in hopes of getting this thread back on topic, the OP was looking for use cases for having two COMM radios. There was a deliberate attempt to not inquire if one COMM vs two COMMs was "better".

There base been a bit of thread drift with some (not all) of the recent posts.

Thanks.
 
Glen,
I use # 2 COMM for ATIS and Ground on the way out from the hangar. #1 stays on tower and departure.

Enroute, #1 is moved through the various ATC handoffs while #2 is used for ATIS and FSS if needed. Ground and the FBO for the destination airport go into the #2 when we get close.

Sure, you can do all that with one comm but its easier with two and you get the redundancy of 2.

FYI, #2 is a lower power transmitter and is the one that stays on when I go on the E-bus due to alternator failure.
 
I have two comms and both can monitor the Standby. On cross-country flights, I have comm 1 tuned to Center. Comm 2 is on Guard (121.5) and comm 2 standby / monitor is on Flight Watch (122.0). I use comm 1 also for Air to Air with the other aircraft that may be with me.

One does not need to have two panel mounted radios. The 2nd comm could be a handheld that is wired into the aircraft. Yes a 2nd antenna and a pigtail lead that is in the aircraft to get the audio and mic of the handheld tied into the the aircraft intercom or radio. If you can build an aircraft including wiring your aircraft, it is not that difficult to tie the handheld into being used as a 2nd comm.

When my aircraft first flew, I only had one radio a KX-125. I added a monitor 2nd radio handheld after a few months. Was nice to talk to ATC and get ATIS without needing to go off frequency. Three years after first flight, did a panel upgrade to approach certified GPS / Comm and SL30.
 
You must log in or register to reply here.
Back
Top