Scott,
I fail to really see where your going with this. I get that if you don't have enough money to buy both units discussed, you would pick WAAS. That is a personal choice! now lets look at it from a more realistic view. If you are IFR and you don't have WAAS you have to shoot a different type approach or wait for the weather to get better. Even if you have WAAS your are still going need the capability to shoot ILS, VOR, and LOC approaches for the next few years because ATC still uses them. You can't go into Midway up there in Chicago and say I want to use the WAAS to RW9. The response would be expect the ILS. Also you don't need WAAS to shoot a GPS approach. You only need WAAS for low GPS approach, so that would eliminate the (how did you put it) "risky circle-to-land procedure". Side note, circle-to lands are not risky, they are difficult. A properly flown circle is no big deal of you know how to do it properly and you have the weather for it. If your weak you can die doing a circle but that goes for any IFR approach. Most of the new avionics are now providing virtual approach modes that allow you to do ILS like approach on all approaches, this might be a better choice then WAAS.
Now going back to the first point WAAS vx TCAS: TCAS works all the time. It tells you when you have a traffic conflict. It is saving you from something you can't plan for or expect. When it works it is the difference between life or death. Non of this can be said about WAAS. My position is that most pilots would get more value out of TCAS over WAAS. The problem is most people thing the other guy will have the mid-air, not me. Ad most importantly it costs to much, TCAS is very expensive. I have TIS and the Monroy 600 in my Lancair Legacy. I wish I had TCAS and am thinking about upgrading my airplane. I do use TCAS at work and could not do my job without it. As for you statement about TCAS being a distraction that is just not true. If you are trained on how to use it you will understand my statement, your statement sir is just fodder. That Monroy 600 never shuts up! It gets the mute switch all the time or I just shut off.
Since 2005 I have had WAAS in my Lancair and since 2003 in my Airbus. I fly the Airbus all over the world, and the Lancair has been to almost every State in the US and Mexico. I have used the WAAS (actually a little different on the Bus but almost the same we use RNP) on the Airbus once in the last six years, and I have never used it in the Lancair. Most of the time the weather is good enough, the approach in use is not a WAAS, or WAAS approach was not available. So dollar for dollar based on what you get out of the unit the TCAS is far superior. TCAS=active traffic WAAS=Better Approach capability. TCAS= $10,000 WAAS (over and above non WAAS)= $2,000 WAAS worth when working and easier day. TCAS worth when working=PRICELESS.
I think both units are great to have and in the future both will be required to fly IFR or they will replace it with ADS-B which does both. Overall this is an apples to oranges comparison.
Mike Larkin
Lancair Legacy (I built it from day one)
Kit fox IV
TS-11 Iskra
A-320
Larkin Aviation Consulting
Angier,
This could be the start of an interesting discussion.
If one primarily flies VFR, TCAS is perhaps more valuable than WAAS (in an FAA approved IFR approach and sole-source navigation box).
If one flies more than occasionally under IFR, the WAAS equipment ranks at the top of the list. "Why?" You might ask. Well.......
1. Sole source navigation devices are usable in non-radar environments - such as during terrain challenged aviating above piles of granite. This also pertains to IFR flights in VFR conditions.
2. There are more GPS approaches with vertical guidance than ILS approaches here in the US and with minimums almost as good as ILS. This virtually eliminates the need to perform risky circle-to-land procedures. It also opens up more airports (GPS only) to choose from in nasty weather flying (more and better located alternates). There are more GPS approaches added continuously at no cost to the Stimulus Plan nor added jobs.
3. TCAS is less valuable because of ATC traffic separation when flying under IFR rules (or even flight following, conditions permitting).
You would have to pry my WAAS device (in my case, a 430W) from my cold dead hands before I would give it up. GPSS navigation (laterally coupled to auto pilot) and approach vertical guidance is a beautiful thing to behold. In general, GPS approaches consist of three 5-mile-long legs (most often in a T configuration). IAF to AF = get to correct altitude and approach speed. AF to FAF = Stabilize approach, check everything twice, hand hovering on gear switch. FAF to RWY (or missed) = descend on VNAV glide slope, shut off AP at DA, make perfect landing. OR, one button-push for guidance thru missed approach procedure. The GPS approaches are so similar that even minimal practice raises one's confidence in a successful outcome during their use, personal limitations, lack of ice build up and all other things considered.
However, my cheap Monroy traffic alerter (TCAS like, approximate distance and altitude difference, no azimuth) usually wakes me up once or twice on long VFR trips (no flight plan or following) with a screaming TRAFFIC NEARBY! and it has saved me from one sure midair, if not more (details released upon any request).
You are right to consider disabling TCAS in an airport environment as it can be most distracting (unless is has non-critical traffic suppression).
Scott Krueger AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL (KARR)