PDA

View Full Version : Gtx330 Pirep


kwmoore
12-31-2002, 06:14 PM
I just brought 812KT back home from El Dorado/Wichita, where it had an annual inspection, then the AirCell removed and a new GTX330 transponder with traffic information exchanged for the GTX327. Mike Sullivan also has a GTX330 in his new 260se and I'm sure he will weigh in with his comments too.

First, I must note that 812KT came out of annual in great shape. There is scarcely any hint of vibration in the canards at any cruise rpm in the 2400-2550 range, thanks to some canard tweaking and both static and dynamic prop balancing. In addition, it looks so far like I gained 1-2 kt in cruise after removal of the AirCell antenna and Todd's canard adjustments. I'll leave the technical details for Todd's commentary, but all I can say is that it's an incredibly smooth machine!

Bevan-Rabell performed the GTX330 installation. There was an initial hiccup in that Garmin shipped the units for installation before the FAA had approved their TIS software for the 430/530 units, an atypical gaffe by an otherwise very heads-up company. This resulted in a 2-3 week delay in completing the installation for delivery. Total installed price, including a credit for the GTX327, was just shy of $4100.

As noted in another thread, I do not view mid-air collision as one of the main risks in flying, and statistics back me up on this. Moreover, Aviation Consumer listed collision avoidance equipment 10th on their list of 10 priorities for improving one's safety ("Setting Priorities," August 2001 issue). Thus I personally could not justify the $20K+ bill for Skywatch or TCAD. However $4K for the GTX330 was just low enough to win me over.

It works as promised--and doesn't work as promised, too. Near Wichita it displayed traffic as little white-outlined diamond icons. Each icon has a "trend line" displayed with it, indicating the target's projected flight path. I like this feature, as it allows one to assess whether a given target is of potential concern. However when a target was making a turn or maneuvering, the software seemed indecisive and the trend line would change markedly with each "refreshing" of the data. Next to each target is also a number such as "+07" or "-10" to indicate its altitude relative to you. I was pleased that I was able to find the aircraft visually in the area suggested by the TIS almost every time. One exception: ATC called out a plane to me that was close laterally but about 2000 feet below, which the TIS did not detect. I suspect that we were not receiving his transponder due to his antenna position (bottom of the plane?).** I suppose this means that a plane could climb into you from below and behind undetected, but I would judge the chances of that happening to be slim.

**As pointed out by Pete below, this interpretation is incorrect. The likely explanation is that the plane was so far below me that the TIS software "decided" not to display it.

When a target is closer than 2 nm and within 1000 feet (I believe) of your altitude, the icon changes to yellow and an aural "traffic" alert sounds through your headset. The voice is female, with a British accent, agreeable yet attention-getting at the same time. Aural alerts can be disabled via the audio panel. I might be inclined to do this when nonpilot passengers are in the plane, especially when departing or arriving at a busy airport.

I flew Todd to ICT to pick up Mike's plane from Bevan, and we were able to track each other on the way back to EQA. At just below pattern altitude, the signal was lost as we sank below Wichita Approach's radar coverage. The British Lady informed me of this by announcing, "traffic not available," which was also noted on the 430 display.

On the trip home, as predicted I lost coverage about 50 nm southwest of ICT, but surprisingly didn't get it again until descending into the Phoenix area. The service map on the Garmin website suggests availability in the Albuquerque area, but it was not active on that day at least. Amarillo is class C airspace, but I guess they don't have the appropriate radar equipment. Descending towards Phoenix Deer Valley from the northeast, service was intermittent below about 6000 feet, presumably obscured by some mountains in the valley. Once I cleared those mountains, we were in business.

Departing DVT, service was available west of the Phoenix area until 40 or 50 nm east of Blythe, and did not pick up again until 30 miles or so west of Palm Springs. It was intermittent while transiting Banning Pass at 4500 feet, and then available until between Santa Barbara and Santa Maria. It picked up again near Salinas and worked well when entering the Bay Area. It was both reassuring and cool to report to ATC that I "had on Skywatch" a Saratoga paralleling my course inbound to PAO even though I didn't have it in sight.

As I do much of my flying in airspace where coverage is available, I feel that this unit is a good choice. However unlike Skywatch or TCAD it certainly won't provide coverage at uncontrolled fields that are below approach control radar service. Compared to Skywatch, I will get more than 50% of the utility at less than 20% of the price, and I'm happy with that.

Pete of N978PB
01-01-2003, 01:54 PM
Kevin,

Thanks for the great report re the GTX 330.

As it happens, I have just received a quote from a different shop for replacement of my GTX 327 with a 330 at a before-sales-tax price of roundly $4,200, net of a trade-in allowance on the 327.

Query: Does your cost of $4,100 include any costs associated with the removal and/or trade-in on the AirCell, or is it a pure number involving only the transponder switch?

Also, you mentioned: "One exception: ATC called out a plane to me that was close laterally but about 2000 feet below, which the TIS did not detect. I suspect that we were not receiving his transponder due to his antenna position (bottom of the plane?). I suppose this means that a plane could climb into you from below and behind undetected, but I would judge the chances of that happening to be slim.'

That confuses me a tad because of the implication that your transponder was not receiving the other plane's transponder signal because it was under his aircraft which blocked the signal from your transponder's antenna.

It is my understanding (perhaps erroneous) that the 330 system works via ATC receiving an aircraft's transponder signal, processing it within ATC's computers, and then transmitting a signal (TIS) to your 330 that tells you where the other aircraft is located.

In other words, the location of the other aircraft's transponder with respect to your aircraft is irrelevant. Thus, the only way an aircraft can climb into you from below and behind undetected would be if its transponder signal is not being received by ATC and its TIS system.

This is interesting because if the controller knew the location and altitude of the other aircraft, one would think that the controller had the information available to him via the other aircraft's transponder squawks. So, why didn't TIS also show it? Was TIS in operation at that location and reporting other aircraft on your screen? I suppose the controller may have had the other chap on his radar sans transponder, and may have verbally confirmed its altitude. Who knows?

Help me out here ... what am I missing ... perhaps I'm just reading more into what you said than what you intended.

Top of the New Year, y'all.

Pete

kwmoore
01-01-2003, 04:25 PM
I dug into this and asked a few questions. You are correct and I was mistaken, the signal is not transponder-to-transponder. Therefore the likely explanation is that the aircraft was too far below me for the TIS software to include it as a target on the display. Had it been closer to my altitude, it likely would have shown up.

The $4100 did not reflect any credit for the AirCell.

kwmoore
01-04-2003, 06:39 PM
Yesterday I was practicing instrument approaches at Sacramento Mather (KMHR). As we were being vectored on downwind for the first approach, we noticed a target on the traffic display that changed direction, position and altitude amazingly quickly. I wondered whether it was a system bug of some kind (or a UFO?) until we changed to tower frequency and found out that a T38 was also practicing approaches to MHR! :p

N75WH
01-10-2003, 04:23 PM
Speaking of interesting sitings at KMHR, last time we were there we tied down on the flight line next to this guy......


I think the 260se could land and take-off on his wingspan.....

N75WH
01-10-2003, 04:24 PM
Here's another shot....

Pete of N978PB
01-10-2003, 07:51 PM
Great Pics ... Big Guy ... but ya know, on the GTX 330 it's just another dinky little diamond :cool:


On picture #2, can you tell what the words are on the fuselage forward of the wing?

Pete

N75WH
01-11-2003, 05:04 PM
Sorry, it was only a 1.3MB camera and its not readable at that resolution.

But, if memory serves, I think it said,

"260000SE
by Peterson"

but I might be wrong.....

kwmoore
01-11-2003, 05:41 PM
Actually, that would have been on the tail. The logo on the forward fuselage would have been:

"2,600,000 hp fuel injection by Peterson"

But I couldn't read it, either. ;)

kwmoore
02-12-2003, 12:52 AM
Avionicswest just put up a review of the GTX330 on their website:

http://www.avionicswest.com/articles/gtx330.htm#2003