Van's Air Force
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GRT version 9
- Thread starter Bavafa
- Start date
Thanks for posting. Version 9 should have a user-selectable transition speed for a HX controlled ADSB-out box like a Trig TT22 to switch from air to ground. This has been a source of a number of "fails" of the FAA test in the past, if you didn't brake moderately hard. I intend to set this number higher than it is now (currently 25 or 30 KIAS?). I certainly will not be in the air (at least not for long!) if my IAS is less than 50 kias.
Martin Sutter
Well Known Member
Just read thru the release notes. Disappointed they still have not included the ability to display CONUS radar from ADSB that shows the entire country instead of just the regional plots limited to a range of 300nm. In an RV it does not take long to outrun that look ahead range when you are flying cross country. I have asked GRT a couple of times for this over the last 2 years.
Martin Sutter
Building and flying RV's since 1988
EAA Technical Councelor
Martin Sutter
Building and flying RV's since 1988
EAA Technical Councelor
Can you please elaborate a bit more on this. I don't think I know what this is or means.
I'm using the Trig TT22 for ADSB-out. It's controlled thru the HX.
ADSB-out has two modes: air and ground. Ground mode includes info like wingspan. The rules require that the ADSB-out box switch automatically to the proper mode. If you have a mechanical squat switch, that does the switching. For our fixed gear aircraft, the HX can switch the Trig between air or ground based on GPS and airspeed. Because some users of GRT have low speed/low stall speed aircraft, the switch over speed was set low so it wouldn't show ground when it was in air. But for the -10, if I let it roll on the runway at 20 knots ground speed, into a 11 knot headwind, it will stay in air mode when it should be in ground, generating an error message on the FAA automated test. For the -10 I can now set the change-over speed higher, maybe 50 kias. That will more quickly change from air to ground on landing, while still triggering air mode whenever airborn.
Thanks Bob for the good and clear explanation, I did not know any of this.
My ADSB-OUT is thru the Garmin 330ES and I have setup my transponder to automatically go to "standby" when below a certain speed and while taxing. I suspect this will automatically take care of it.
Totally different context..
Properly and reasonably promptly transmitting Ground mode is part of the FAA test of ADSB-out. The transponder must remain in ALT mode, I think, for this to happen. Definitely not standby.
Sorry, I meant to say "Ground" mode.
I have the HXr in my 6A with at Trig. I am getting my 430W installed this weekend and hope to do the FAA test next week. The beta s/w that GRT gave me had a setting that went down to around 30 and also had an AUTO setting. Is 30 knots low enough to pass the FAA test?
Larry
Auto is about 30 kias. FAA really wants the box to switch from air to ground mode on touchdown, but they allow some extra time (maybe 20 seconds?) to make the switch. So if you brake moderately hard, yes you can pass. Remember if you have a 20 knot headwind, you need to get down to a 10 knot ground speed for it to switch. But if you set the speed higher, it will switch sooner in the landing roll out, increasing the odds that you won't have trouble passing the FAA test. Just don't set it above the stall speed (full flaps, ground effect). If you do that, it could switch to ground while still in the air. Personally I'd try 40 or 45 kias for the switch over speed.
PS. Sounds like you're paying to have the 430W installed. Make sure they wire at least two RS-232 output ports. One to send data to the HXr, and one direct to the Trig (this one needs the Garmin set to "ADSB+"). Plus an RS232 in port from the HXr. You'll also want the ARINC lines to/from the 430 and HXr wired.
PPS. GRT web site now has the latest (non-beta) software posted.
Also I presume you've already signed up for the $500 rebate.
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Yes to all. I appreciate the guidance and have already planned all of those steps. I also will run an RS-232 port to the Mini-x, which is my backup. I am wondering what the 430 would do if I have two distinct EFIS/Air Data inputs. There will naturally be slight differences in the data. It would be great if both could be connected, but I am thinking that I will need to have the Mini's output turned off unless the HXr fails. I could either turn it on in s/w or use a relay with reversion switch
I will try 45 Kts on the transition speed and see if that works.
Larry
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