For VFR Flying

Since I live under class B airspace, I require both a hassle-free, reliable Com and a transponder.  The requirement for hassle-free and reliability rules out handheld COM for me, and I assume that the aircraft does have an electrical system (all of mine do).  Although my transponder is welded to squawking 1200, the Com should have flip-flop tuning since in any given flight I'm changing frequencies at least three times on departure and again on arrival (ATIS, Ground, and Tower).  A good intercom is also a requirement for safety and passenger comfort.

For navigation I do not think that panel-mounted avionics are the most cost-effective for VFR flying.  The best tool is a GPS navigation unit, and the cheapest and most functional GPS navigators are found in handheld units.  Panel mount units lag behind in functionality and are typically several thousand dollars more expensive than handhelds because of certification requirements.  Also since the GPS navigation technologies are still maturing, a handheld lets you upgrade more often and avoids the more permanent commitment that a panel mount implies in terms of aircraft wiring expense.  My personal handheld GPS pick:  Garmin 295.

The in-aircraft stack consists of:

• PS Engineering PM3000
• Apollo SL40 COM
• Apollo SL70 Transponder
  

I really like the Apollo line of avionics and have had an excellent experience with the SL40.  Good attributes of the Apollo line are:

• Sturdy, well built unit.  Just feels solid and is easy to use.
• Software programmable configuration.  No more trimmer pots located on the bottom side of the unit requiring tedious removal/reinstallation to adjust.
• Short height.
• Well written installation instructions and beefy installation trays.
• Priced reasonably.

The Apollo SL40 COM combines a good radio with flip-flop tuning and a frequent channel memory.  It also has a unique feature that lets you monitor the standby frequency while still tuned to the selected transmit frequency, which is handy for picking up ATIS while staying on with ATC main frequency.

The Apollo SL70 transponder offers a bonus of showing the encoder altitude so you will immediately know if your encoder is on the fritz and ATC is about to bust you.

For intercoms I've had good experiences with PS Engineering's line.  The PM1000II is a great mono intercom, and it has music inputs.  With stereo headsets becoming widely available, I'd consider wiring up a stereo system and using the PM3000 stereo intercom if you plan to plug in a music device for long cross-country trips, such as a portable CD player or MP3 player.

Other non-visible avionics:

• ELT.  I've installed an Ameri-King AK-450 unit, and it is pretty good.  It uses standard D-cell batteries.  Unfortunately, like all new ELTs, it has a remote annunciator panel that must be mounted in the line of sight of the pilot.
• Blind encoder.

I recommend installing the ELT annunciator panel next to the intercom, and the external audio in jack adjacent to one of the headset plug-ins on the passenger side.

For Light IFR Flying

Light IFR is sort of an oxymoron, since you immediately start needing more and more equipment to be really safe.  Technically you could get away with a Nav/Com and a transponder, but I don't think this is very safe nor is it very cost-effective given the greatly increased utility of a GPS for both IFR and VFR flying.  I'm assuming that VFR flying is the more common mission and that the IFR capability gets used very rarely.  My mission would to be be able to move aircraft to or from a fly-in on a schedule and get through bands of clouds or moderate ceilings, but maintain rigid personal minimums and don't take risks.

So I think the minimum IFR panel does consist of a GPS moving map, and it should contain precision approach capabilities.  With the current stuff on the market there are a number of ways to put this together.  My suggestion number 1 is:

• Apollo GX50 IFR GPS
• Apollo SL30 Nav/Comm
• Apollo SL70 Transponder
  

The Apollo GX50 is a fine moving map GPS and it is approach certified.  It doesn't support color.  You can get the same GPS unit combined with a COM radio in the Apollo GX60, which would offer the additional redundancy of a second COM radio.

With this configuration you're also going to need external CDIs.  If you have the panel space I'd go with two dedicated CDIs, and enunciator lights for the GPS.  This is a more versatile configuration and it lets you use the GPS to drive CDI guidance for cross-fixes and locator beacons which otherwise you'd have to get off the map.  If you don't have the panel space you'll need to have at least one CDI and a switcher box and the enunciator lights.  Apollo and others make combined switcher/enunciator boxes which have to be mounted somewhere visible.

You also don't have marker beacons built-in with this configuration, and you need them for ILS approaches.  Therefore you'll need an external marker beacon receiver, or you could get marker beacons combined with intercom and an audio panel.  If you have the second COM option then the audio panel starts to become a requirement.  A more reasonable setup is therefore something like this:

The PS Engineering PM7000 (or the Apollo SL15, which is the same unit OEM'ed with an Apollo label) is a bit of overkill here, because you don't really need a full audio switching panel.  A lower-end panel would work ok, but the PS Engineering unit has a great intercom, built-in marker beacons, and an innovative audio enunciator feature which is long overdue in general aviation aircraft.

Combined with the GX60 Map/Com, this is really close to a fully functional IFR panel.  The only thing missing is dual VOR capability.  Given GPS's area navigation, the ability to substitute for DME, and the obvious obsolescence of ADF, there's no good reason to invest in other more traditional IFR equipment.

As you can see, avionics start to be a very slippery slope very quickly.

Getting back to the original concept of light IFR, I think suggestion number 2 is more practical (although probably more expensive).  This stack is as follows:

The key component here is the Garmin GNS430, which combines a IFR approach-certified GPS Map, Com, VOR, and ILS receiver into one box.  This is almost IFR-in-a-box, except it is lacking marker beacons for precision approaches.  And, of course, there's no redundancy, but this is largely true for all of the "light IFR" proposed panels.

I also opted for the audio panel in this configuration, again to get the marker beacons and intercom along with audio mixing.

I decided not to go with the Garmin transponder, first because there's no reason not to mix and match transponders, and secondly because the available Garmin product is a higher-height, mechanical "tuning" interface.

The last panel is what I think is the best modern full IFR panel choice available that does not use large-size MFDs.  The MFDs offer some amazing functionality, but I don't think the market is mature for them yet and there's still much innovation to come over the next few years.  I'd wait before investing.  The panel is:

This gives you full IFR GPS, dual Navs, and dual Coms.  There are variations, of course, such as having two GNS 430's (overkill, very expensive, and uses more height in the panel), or using the GNS 530 instead of the GNS 430 (bigger map screen size).