Validation Flight - ADSB Out - GTX 335

[John W SBA]

I have just sent in the ADSB Out rebate code for $500 toward an
investment of perhaps 1/5 the value of my 172. I chose the Garmin GTX
335 1090ES that's Out only, since portable devices seem to me better and
cheaper for ADSB In than the extra for anything panel mounted. I also
helped with the installation and learned a lot in the process.

My next, hopefully smaller, investment & challenge is getting reliable
ADSB In displayed in Avare. Ideally on both a wireless receiver that
won't drain my Android battery, and as a backup via the HIZ Pro app
using my SDR dongle. I also want to explore any differences between the
two methods (HIZ Pro and Avare I/O).

In case it's helpful to anyone else who still has the "Validation"
flight to do, here's my understanding of the arcane language about "rule
airspace" where the flight must be done. Although I flew slowly from
SZP back to SBA a couple of days ago after installation in order to show
up on ADSB, only 9 minutes of the flight qualified for rules airspace.
I'd read that people had just flown near Class C airports like SBA
successfully, my understanding now is different. Anything above 10k'
would work, but the easier method for me was to simply fly in or above
the Class C outline so I did that today. Rather than annoy ATC by
flying above the 4k'AGL Class C surface area, I flew slow figure eights
at 4.5k' over the East outer shelf. By staying within or over Class C
airspace, the entire flight qualified.

I have the excellent HIZ ADSB Pro app, but was unable to get it
displaying UAT even though there were several aircraft passing near me
during the flight. I'm going to look into that in more detail now, and
re-check my related Avare settings. I notice in the FAA report that my
Out configuration doesn't note In capability, so maybe that's the
problem. I also plan to invest in either the new wireless HIZ ADSB In
receiver or a Stratux.

I'm happy to answer any questions about the process, and welcome any
pointers others would like to share about getting reliable and complete
UAT ADSB In.

Happy Flying -j

[bman]

I also chose the 335 for my ADSB solution.  I too wanted the flexibility moving forward of other "In" options not related to the ADSB solution.  There is some question under STC rules that if the "in" portion of the transponder fails, the transponder itself is considered to be a failed piece of equipment and must be removed or repaired. 
I had to refly the verification flight because of the "ground" portion of the test.  I believe the problem was that I started to move before the GPS receiver in the 335 had switched to WAAS.  Most "ground" problems with Garmin have been because the taxi to flight software switch is at 45 knots.  To my surprise, a later flight below 10k from PA to Chicago met all the requirements.  I was not technically in the defined airspace for the necessary time but the entire flight was under and IFR clearance.  For some reason it worked. You are correct, a flight above 10k should work just as well as flying around Class C or B. From what I understand, you are also correct that in setup, your shop should note in the FAA file that you have ADSB In capability so the system will send traffic data to you.  Weather data is sent out all the time to everyone.

I have used a DUAL receiver and Stratux.  I prefer the Stratus receiver.  The DUAL receiver is now just a backup.  Stratux is lower cost, lower power consumption, has remote antenna, runs cooler and is easier to repair/upgrade.  I had an intermittent bluetooth problem with the first box and simply replaced the computer board for $35. With the remote high gain antennas in the back window I get two or three times the number of ground stations as the DUAL. Finally, because of WIFI connection, the Stratux can simultaneously work with Apple or Android without the bluetooth protocol switching requirement.  Finally, because the WIFI signal sent by the Stratux is one way - out data - it can be received by more than one tablet or phone even if they are running different software.

[John W SBA]

> I also chose the 335 for my ADSB solution.

Thanks for the reply. :)

I like the unit, but would have chosen something else if there'd been a
local shop ready to do it and let me help/watch. I'm not a fan of
Garmin, so your informed choice helps me feel better about it. As the
installer said, the company's very likely to still be there in 20 years
and that's reassuring too.

> if the "in" portion of the transponder fails

I recall reading something about that, and that it applied to *required*
In only. So if the installer didn't use the required equipment code it
wouldn't be a problem?

> started to move before the GPS receiver in the 335 had switched to WAAS

I'm glad you mentioned that because I'd forgotten. Guess I was lucky in
having idled on the SBA ramp for a few minutes fiddling with ADSB In
before taxi, near the field radar tower with the 335 "Respond" indicator
flashing. My prior 80kias SZP-SBA flight only showed 9 minutes in Rule
Airspace, and I didn't notice whether they included the landing/taxi as
Ground Validation (no radar at SZP).

> taxi to flight software switch is at 45 knots

I wonder if students doing 172 stalls will show as Ground, not to
mention the various STOL planes out there.

> above 10k should work just as well as flying around Class C or B

We much prefer ~2k'AGL, and I'd have done that if not more work for ATC.
Even 3k' would've probably worked (1.5-4k' shelf), but some inbound
traffic is 2-3k' there. It was unique maneuvering at ~75kias/~5k'AGL in
that area so familiar from ~2k', so with no traffic to worry about we
enjoyed noticing new things from a higher perspective. Climbing above
10k' just seems like a waste of fuel getting too high for good
sightseeing, but for many pilots maybe it's the best option. Being
retired, we opt for low/slow and try to avoid impeding the beautiful
V-tails (and P-51s, etc.) we so enjoy watching. Crossing the Mojave at
127kias my wife sometimes wishes we were in a Beech. ;)

> your shop should note in the FAA file that you have ADSB In

One of the things I dislike about the 335 is the inability to change
that myself. Hopefully the shop won't charge me for doing it.

> I have used a DUAL receiver and Stratux. I prefer the Stratus

This is very helpful info, and I much appreciate you detailing the
advantages.

Happy Flying -j

[Chip Davis]

On 10/9/2017 2:46 PM, John W SBA wrote:
> I have used a DUAL receiver and Stratux.  I prefer the Stratus
>
> This is very helpful info, and I much appreciate you detailing the
> advantages.
>
> Happy Flying  -j

I assumed that was a typo, bman.  If you _do_ prefer the StratuS over
the StratuX, please elaborate.

-Chip-

[John W SBA]

> I assumed that was a typo, bman.  If you _do_ prefer the StratuS

Thanks for noticing, Chip. I didn't as you can tell, thought he was
talking about the StratuX, and like you look forward to his reply.

-j

[John W SBA]

I'm now looking up FAA sources for details on how to get my HIZ/SDR
displaying TIS-B (traffic) on the Map screen in Avare. Attached is an
image of the "hockey puck" coverage area I should be seeing, edited to
include the URL (bottom-right) where I found it:
https://www.faa.gov/nextgen/equipadsb/ins_and_outs/

Of interest to me for the Out code setting for In capability is this
item in the page:
In order to be considered a TIS-B/ADS-R "client" by the ADS-B ground
stations, an aircraft must meet the following criteria:
1. Be in a region where ADS-R or TIS-B are offered.
2. Be ADS-B Out equipped and have produced valid.
position data within the last 30 seconds
3. Be ADS-B In on only one link.
Related to item 3 in particular, it seems coding for UAT In Only would
be best since my understanding is that 1090ES air-to-air TIS-B is sent
non-stop regardless of my Out code. Coding my Out for both would
prevent receiving UAT TIS-B In. Hopefully there is or will be an
inexpensive dual In receiver that auto-switches to 1090ES when UAT is
unavailable.

On that page they also mention this 2015/12/10 AIM PDF:
https://www.faa.gov/air_traffic/publications/media/aim.pdf
In that PDF section 4−5−8.b.1 they state:
"Aircraft must be equipped with an ADS−B transmitter/receiver or
transceiver, and a cockpit display of traffic information (CDTI)."

This would seem to officially validate that my ADS-B Out needs to
transmit the UAT equipped code for my "puck" to be activated.

In the PDF section 4−5−8.c.2 they state:
"Only transponder−equipped targets (i.e., Mode A/C or Mode S
transponders) are transmitted through the ATC ground system architecture."

So I'll still want flight following for the chance of advisories on
"primary only" targets detected by radar without transponder. Around
here we see quite a few of those, many also without (or not using)
radios. Of course as noted in 4−5−8.d.1, ATC often doesn't detect or
advise us of those so "see and avoid" is still paramount.

They add this interesting note: "No aircraft avoidance maneuvers are
authorized as a direct result of a TIS−B target being displayed in the
cockpit." This seems to contradict my understanding that PIC can take
any action deemed important to flight safety, and that will remain my
policy (certainly when VFR). They subsequently offer a useful outline
of TIS-B limitations.

I've read that dual-In receivers often display "shadow" targets, where
the same (including Own) aircraft is shown in two locations. This is
due to the delay induced by ground station reception and re-transmission
of ADS-B Out location reporting.

Question: In the three requirements outlined in the FAA Ins & Outs page
above, there's no mention of an ADSB Out code setting for UAT In
capability in order to receive UAT. Can anyone provide an FAA reference
on that?

[bman]

Yes, I meant Stratux.  Darned autocorrect!!! 

On Monday, October 9, 2017 at 5:06:56 AM UTC-4, John Wiley wrote:

[bman]

Aircraft without transponders will never show up in the ADSB world.  This will be true of non-TRACON service areas once 2020 arrives and the FAA does away with radar except in the areas typically handled by approach.  And, yes, you are correct that a dual frequency ADSB receiver will "see" 1090 traffic directly without the aid of ground re-transmission.  They also show up whether the 1090 equipped aircraft are talking to ATC or not.  Those UAT aircraft will be seen only through ground station broadcast of TIS-b traffic.

I can't put my fingers on the FAA requirement that your ADSB equipment must be coded as "in" capable, but I am quite certain that it is required to receive the ground transmission.  It is one of the setup code items on page 6-6 of the Garmin Installation Manual.  FYI - the regs do not require that the "in" receiver is integral or even STC'd.  So your shop should just be able to set the code to "in" capable if you have portable equipment.

I think the "authorization" for maneuvers is to simply put the responsibility on the PIC, who can do anything anytime for safety - and have to explain it later.  That note would seem to just say you can't take a TIS-b displayed conflict as FAA authorization for maneuvering that would be outside of an IFR clearance.

On Monday, October 9, 2017 at 5:06:56 AM UTC-4, John Wiley wrote:

[John W SBA]

> coded as "in" capable, but I am quite certain that it is required

Thanks for the followup. I'll keep looking for a reference and will
post if I find one. Meanwhile I've emailed the shop about getting the
In setting changed to UAT.

[John W SBA]

Today I flew CMA->SBA with the Garmin 335 sending UAT In Capable, and it
partially worked with the HIZ ADSB Pro app. I'm going to start another
Topic here on that, but wanted to share here how I changed the setting
in case it's helpful for anyone else flying a 335 who hasn't yet figured
out how to do it.

My installer of course "should" have done that setting for me, or at
least asked if I'm using a portable ADSB In receiver. Anyone buying a
335 (vs 335R that has In), would most likely have some sort of In
capability. I emailed them and of course have received no reply, since
they have my money. :)

So I searched online, and to my mild surprise found the answer in the
Garmin *Installation* manual. There's no sign of it in the Pilot Guide,
nor is Google able to find the Installation Manual anywhere on
garmin.com (wonderful user support!). I found it here:
http://joesrv12.com/Garmin/GTX%20345%20TSO%20190-01499-02_4.pdf
Apparently a guy named Joe built a nice RV-12, got the Install Manual
somewhere, and was kind enough to share it. The actual Garmin file name
is apparently 190-01499-02_4.pdf and applies to both the 335 and the 345
which has a built-in ADS-B In receiver. Garmin has the 335R (remote
mount)installation manual on their site, but not the 335. Closest thing
on the Garmin site is this:
https://support.garmin.com/support/manuals/searchManuals.faces
It lists only three documents:
http://static.garmin.com/pumac/190-00734-15_2.pdf
http://static.garmin.com/pumac/190-00734-16_01.pdf
http://static.garmin.com/pumac/190-00734-11_5.pdf
Anyway, I found my answer in the one Joe kindly posted.

In that 190-01499-02_4.pdf document in Section 6.3 Configuration Mode
and Settings on Page 6-2 is this:
On a panel mount unit push and hold the ENT key and apply power to
enter configuration mode.
• Push and hold the OFF key until the unit powers off to exit
configuration mode.
• Push the FUNC key to cycle through the group pages.
• Push the 8 or 9 key to scroll up or down on the page without an
active field selected.
• Push the CRSR key to access items on the page.
• Push the 8 or 9 key to cycle through the selections of an item on
the page.
• Push the ENT key to move within the page with a field highlighted
or to accept setting.
• Push the CLR key to move to previous selection on the page.
• Push the FUNC key to exit the page.

In the ADSB configuration section (6.9) on Page 6-26 is this:
NOTE
Both 1090ES and UAT In settings can be set to YES when a portable
ADS-B In receiver system, such as a GDL 39, is installed. It is not
necessary to install a certified ADS-B In system.

Next, on Page 6-27 is this:
1090ES IN CAPABLE
Select YES if the aircraft can receive 1090ES ADS-B messages.
UAT IN CAPABLE
Select YES if the aircraft can receive UAT ADS-B messages.

My understanding from the FAA docs is that it's better not to have both
set to On. 1090ES is air-to-air, and apparently sent regardless of my
ADS-B Out capability code. So when not receiving UAT ground data, I can
still get 1090 direct from other aircraft. But when using UAT, 1090
would be sent both by aircraft and in the UAT data stream. Apparently
that can cause "ghosting" where two targets are displayed in close
"formation" since the UAT sends a slightly delayed re-transmission of
the aircraft direct signal. If someone knows otherwise or I find
something different in practice, let's post here about it.

It was great seeing how much traffic was nearby (<4nm) with at least a
transponder! I could only see about 1/3 of it in today's haze from
wildfire smoke, despite knowing location and altitude. But when ATC
called with an alert I'd already been watching them. I'd like to have
configurable traffic alerts but after a few minutes it's easy enough to
make it part of the scan.

[John W SBA]

ps- Another setting I found and changed but haven't yet tested is in
190-01499-02_4.pdf in Section 6.6 Unit Settings on Page 6-16:
RESTORE PAGES ON POWER-UP (PANEL MOUNT UNITS ONLY)
To save the selected pages set in normal operating mode as the new
default page settings next time the unit is power up, select YES.

What I'm hoping is that this will retain my preference of the normal
display showing Pressure Altitude rather than the default "Flight ID"
(tail number). Obviously I know the tail number, but sometimes it's
handy having the Pressure Altitude on screen so I know what ATC is
seeing and in case I'm calculating Density Altitude. My 172 has an
outer ring that gives approximate PA after twiddling and reading the
tiny half-worn numbers. I haven't checked yet, but it will be nice if I
can now have PA by default on the display. :)

In the Pilot Guide, Section 2.4 Function Keys, Table 2-3, Page 2-4 the
categories of displayed info that can presumably then be the default at
next power up:
The FUNC key cycles through four menu groups shown on the right-hand
side of the display. Menu groups include:
◦ Transponder (XPDR)
◦ Timers (TMR)
◦ Altitude (ALT)
◦ System (SYS)

pps- Correction: In the prior email I wrote that 335R has an In
receiver, but of course that's only in the 345. The R as noted
elsewhere in that email, denotes a Remote (not panel mounted) 335 or 345
model.

[bman]

Outstanding work, John. Thanks!

I am not sure how mine was set up, but my 335 returns to the last selected info page on each startup. So whatever you normally use will return each time.

It is nice that the 335 tells you the altitude your xponder is sending out - which is not adjusted for current altimeter and therefore almost never what your altitude really is. Only when current altimeter setting is 2992 will they coincide.