Traffic info on GNS430

[jasc15]

This past weekend, I had some training in a DA20, which had a GNS430. I noticed that there was traffic info displayed on the screen. I always thought a plane needed its own radar for that, but there must be some ATC feed to the unit. How does this work and what are the limitations?

 

[John Collins]

This past weekend, I had some training in a DA20, which had a GNS430. I noticed that there was traffic info displayed on the screen. I always thought a plane needed its own radar for that, but there must be some ATC feed to the unit. How does this work and what are the limitations?

More than likely, the traffic information is being received by a GTX330 Mode S transponder. The mode S transponder includes a data link that the ground based ATCRBS computer system can use to send traffic data to your aircraft. The traffic data is called TIS and can include position and vector data for up to 8 of the nearest traffic targets. The computer formats the data with distances and direction relative to your aircraft. A rough vector for the relative direction of flight is also provided. The targets covered are up to 7 NM from your position and +3500 to -3000 feet above and below. Not all ATCRBS radar systems have this capability, and you must be within the service volume of the system that does have it.

 

[AggieMike88]

More than likely, the traffic information is being received by a GTX330 Mode S transponder. The mode S transponder includes a data link that the ground based ATCRBS computer system can use to send traffic data to your aircraft. The traffic data is called TIS and can include position and vector data for up to 8 of the nearest traffic targets.

Excllent description.

I did all my training in a DA20 with the setup described above. While I loved the aircraft, the instructors mild "obsession" with the TIS screen was somewhat distracting. Had to mention it a time or two and remind him that we were teaching me "eyes out of the aircraft". It's too easy to wind up staring at it and not be looking outside for the actual target.

It is helpful in busy environments, and untowered environments.

But you need to remember there is a notable lag between reality, the radar facility sensing the return, computing it, and then broadcasting it back to you. By the time your 430's display shows the aircraft going past you 1-2 miles off your 9-o'clock, it likely has already gone past.

It's a useful tool for sure. But one to enhance situational awareness, not replace the standard mark-1 eyeball.

I would welcome it into any aircraft I would own. But again, just to aid in knowing what sector of sky to spot the target.

 

[JOhnH]

More than likely, the traffic information is being received by a GTX330 Mode S transponder.

Is this system any better for collision avoidance than the ZAON TACS I currently have connected to my 496? I ask because I am told that when I connect my new 530w to the 496 I will lose the ability to connect the TACS to the 496. I have not yet found out if I can connect the TACS to the 530.

 

[poadeleted20]

I love my TIS -- it has on many occasions alerted me to traffic farther out than I can see, and guided my eyes to where it was so I spotted it when it came into visual range. It's also been useful when ATC screws up, like Saturday when they called traffic at 2 o'clock, and the TIS showed it was at my left 2 o'clock (aka 10 o'clock). OTOH, it is also a Siren to lure one's eyes into the cockpit when they should be out, and that bears considerable caution.

 

[jasc15]

OTOH, it is also a Siren to lure one's eyes into the cockpit when they should be out, and that bears considerable caution.

I pretty much ignored it, although like AggiMike described, the instructor was mildly obsessed with it. I used the 430 for radio tuning as that was one of the few things I knew how to use on it.

 

[AcroBoy]

The combo of GTX330 and a GNS530/430 is great. There is an amazing amount of traffic out there that even a good scan won't pick up. If maneuvering fast, it can give a false reading- I have one in my acro plane, and it cam be disconcerting to hear a traffic alert when going straight up or down, or flying inverted, looking around wildly only to then realize it was my own return!

 

[gismo]

This past weekend, I had some training in a DA20, which had a GNS430. I noticed that there was traffic info displayed on the screen. I always thought a plane needed its own radar for that, but there must be some ATC feed to the unit. How does this work and what are the limitations?

First of all "radar" in an airplane doesn't have anything to do with displaying traffic. The ground based traffic control radars are associated with the ATCRBS (aka Air Traffic Control Radar Beacon System or "secondary radar") but only to the extent that the ATCRBS antenna is mounted to the top of the primary radar antenna and returns from both can be displayed on ATC scopes.

There are four types of in-aircraft traffic systems for GA. Here's more than you probably wanted to know about them:

One is called TIS and only works at some TRACONs (approach radar installations). This system works by taking the position of each aircraft within range that has a Mode S transponder and computing the relative bearing/distance for other aircraft (transponders actually) nearby, then sending that information up to each mode S equipped aircraft via the same radio channels used for all transponders. A common setup in an airplane for TIS includes a Garmin GTX330 mode S transponder and a GNS430/530 GPS navigator. Only traffic carrying transponders (mode S or C) that are being tracked by the TRACON radar can be displayed and then only when the subject aircraft (the one with the traffic display) is within range (vertically and laterally) of the TRACON radar. Typical installed cost (assuming the 430W is already in place) is around $4k making this one of the least expensive ways to get "full" (i.e. with accurate distance and relative bearing) traffic display in a small airplane.

Another (much newer) system is called TIS-B and is totally unrelated to the TIS described above except that Mode-S transponders can support it. This system is a part of the ADS package that requires almost all airplanes to broadcast their GPS position by the year 2020. TIS-B is the name for the part that rebroadcasts the location of all ADS equipped aircraft along with the location of non-ADS aircraft tracked by ATC radar via a mode-S uplink similar to (but different than) TIS. The Mode-S channel is called ES (Extended Squitter) and TIS-B also communicates with aircraft on a different frequency using a piece of in-aircraft equipment called a UAT. Prices for this stuff is fluctuating but ought to be close to what it currently costs for TIS. The ground equipment for TIS-B (and ADS) is being installed today but AFaIK it will be several years before the entire country is covered. Unfortunately the spec's for much of the aircraft portion are still in flux and there's not a lot of actual approved hardware available yet.

The other two system categories require no participation from any equipment on the ground, and just a simple mode C transponder in the aircraft being tracked. One of these categories is passive (receive only) and the other is active (transmits interrogation signals to other transponders). Most but not all passive systems are portable devices (e.g. Zaon and Monroy) but Ryan did sell a passive version of their 9900 TAS (Traffic Advisory System) which had it's own panel mounted display for a while. Passive systems "listen" to the Mode C replies from the transponders in other aircraft and provide the user with information about the range (distance), relative altitude, and in some cases relative bearing of multiple nearby targets. The range information is estimated from the signal strength of the replies and is horribly inaccurate much of the time. The altitude info is computed by comparing the altitude transmitted by your own transponder with the data in the replies from the other aircraft and it therefore usually pretty close. Relative bearing (i.e. where to look) ranges from non-existent to marginal with most of the portables, especially when using their built in antennas inside a metal airplane. Another shortcoming of passive traffic detectors is that they only see airplanes when their transponders are interrogated by an ATC radar on the ground or the active traffic system of another aircraft. And a typical problem with many of these is the occurrence of false targets resulting from the unintended detection of your own transponder (guess what relative altitude and distance goes with these false alarms).

Active systems come in several flavors from relatively inexpensive (<$10k) "TAS" types to TCAS-II units costing more than most piston airplanes. The lowest cost systems provide fairly accurate range, bearing, and altitude out to 5-10 nm and can display the traffic on MFDs as well as dedicated displays in some cases. TCAS types go a bit further and actually provide the pilots with verbal "instructions" for avoiding serious conflicts.

At least two of the active TAS manufacturers (Garmin and Avidyne) have released or are planning to release equipment that will integrate TIS-B traffic where available.

 

[BillTIZ]

TIS is limited where you can receive it. Fly away from our ClassB and you'll get no more updates until you get down into the LA valley or another area like PHX thaw has the TIS rebroadcast.

Also, I've found that with the time delay, check the other aircrafts track on your display and look ahead of where it is. Head on traffic is closer than you think.

 

[ronnieh]

Gismo nailed it. IMO the TIS is very limited in its use. If not in a Radar enviroment it does not work. I had it in a PA31 I use to fly and mostly ignored it. The plane I fly now has the TIS-B and works much better. Neither gives direction of flight of the target (at least mine did not) Only shows direction and distance of target and how far below or above you it is. The TIS-B shows if the target is climbing or descending. By the time you figure out which way the target is going you may be past it. I find it most helpful to use it with radar if available. Of course down low at an uncontrolled field it can be useful.

 

[denverpilot]

Garmin has a TIS coverage page...

http://www.garmin.com/aviation/tis.jsp

During some recent CAP training where you're trying to operate as a coordinated crew and maintain a sterile cockpit and listen to the traffic calls at a busy airport, I found the frakkin' G1000 urgently announcing "TRAFFIC! TRAFFIC!" -- when you already know you're headed into a busy Tower-controlled pattern with three active runways and aircraft using all three... is just annoying as hell.

Especially with a crew of three already calmly spotting and pointing out traffic the pilot hasn't already spotted.

I was not the pilot. But if I were, it would have been ignored.

I'm sure there's some way to shut the G1000 up, and I'll have looked it up by the time I'm sitting in a three-crew flight in the G1000 C-182 again. If I'm in the Pilot or Observer seats, my finger will be ready to shut that crap off.

That will also become an item for the crew safety briefing when I'm on board...

"Traffic calls by the TIS will be monitored by the Observer. PILOT will always remain eyes-outside at or below 1000' AGL. PILOT will NOT look inside at the TIS display. Observer will point out traffic once spotted from TIS data, to Pilot or advise if a turn or deviation is necessary."

 

[Steve]

Gismo nailed it. IMO the TIS is very limited in its use. If not in a Radar enviroment it does not work. I had it in a PA31 I use to fly and mostly ignored it. The plane I fly now has the TIS-B and works much better. Neither gives direction of flight of the target (at least mine did not) Only shows direction and distance of target and how far below or above you it is. The TIS-B shows if the target is climbing or descending. By the time you figure out which way the target is going you may be past it. I find it most helpful to use it with radar if available. Of course down low at an uncontrolled field it can be useful.

Unfortunately, at many relatively remote uncontrolled fields if you're down low you're too low for ARTCC radar to detect your transponder so it can't tell the other plane you're out there on TIS. Had it happen to me a couple of days ago, a biz jet was inbound as I was climbing out. His unit didn't see me until I climbed into radar coverage, about 1800 agl. We were talking to each other on unicom and never closer than 5 miles, but that's close for a jet guy.

 

[azure]

Gismo nailed it. IMO the TIS is very limited in its use. If not in a Radar enviroment it does not work. I had it in a PA31 I use to fly and mostly ignored it. The plane I fly now has the TIS-B and works much better. Neither gives direction of flight of the target (at least mine did not) Only shows direction and distance of target and how far below or above you it is. The TIS-B shows if the target is climbing or descending. By the time you figure out which way the target is going you may be past it. I find it most helpful to use it with radar if available. Of course down low at an uncontrolled field it can be useful.

Hmm. My TIS-B setup shows direction of flight too. It uses the now-obsolete (and way too expensive) Garmin GDL-90 though (978 MHz UAT), displaying on a GMX-200 MFD, so this may not apply to other installations.

As far as ADS-B coverage goes, I made a run to PA last week (from the Detroit area) and had traffic on my screen the entire way. Last summer I had traffic all the way up to MCD. Coverage is getting better and better and is probably upwards of 95% now throughout the Great Lakes, maybe the whole Eastern US. (Hard to say, since the FAA's nationwide coverage maps seem to always be "projections".) This is IMO a very nice and very useful system, the data seems to be fairly current, never more than 10-15 seconds old, and yes it does show altitudes and whether climbing or descending. Hopefully at least the "in" part will soon be available at a reasonable price point. I certainly wouldn't have paid the ~$10K to put my current system in, though it's great to have.

 

[ronnieh]

I wish mine gave a direction vector for the target. It only has an arrow pointing up or down showing if the target is climbing or descending. Difference in the install I suppose. As somebody said earlier about the TIS when you need it most is when you are below radar.

 

[PittsDriver]

TIS is definitely a big step up from nothing but it's also a big step away from active traffic onboard. My daughter and I would not be here today if not for traffic my 9900BX saw that the Atlanta Center said wasn't on their screens.

 

[BillTIZ]

You'll love it when the "traffic" call goes off at 100ft AGL when the plane at the hold line goes from stby to alt!!

Garmin has a TIS coverage page...

http://www.garmin.com/aviation/tis.jsp

I'm sure there's some way to shut the G1000 up, and I'll have looked it up by the time I'm sitting in a three-crew flight in the G1000 C-182 again. If I'm in the Pilot or Observer seats, my finger will be ready to shut that crap off.

That will also become an item for the crew safety briefing when I'm on board...

"Traffic calls by the TIS will be monitored by the Observer. PILOT will always remain eyes-outside at or below 1000' AGL. PILOT will NOT look inside at the TIS display. Observer will point out traffic once spotted from TIS data, to Pilot or advise if a turn or deviation is necessary."

 

[KSCessnaDriver]

"Traffic calls by the TIS will be monitored by the Observer. PILOT will always remain eyes-outside at or below 1000' AGL. PILOT will NOT look inside at the TIS display. Observer will point out traffic once spotted from TIS data, to Pilot or advise if a turn or deviation is necessary."

Seems a bit extreme to me, but whatever floats your boat. If a pilot can't spend 2-3 glancing inside to take a look at the screen and not crash into something, perhaps they shouldn't be a pilot at all. Yes, in a multi-pilot environment, it may not be needed for the pilot to look inside, but you get the point.

 

[denverpilot]

3 seconds at 90 knots is roughly 500' of ground covered. And unless you're really good, I'm guessing most pilots are really removed from the outside scan... Not just looking out the window, scanning. They're different... For at least ten seconds each time they have to bring eyeballs inside.

I'm thourougly convinced three people wouldn't be dead over Boulder, CO last year if the Cirrus guys were eyeballs out. 1500' of movement is the difference between a mid-air and a close call when reaction time is factored in. Easily.

With a trained three-person crew, the only time the pilit's eyeballs should come inside are for critical instruments like airspeed. Single-pilot, you have no choice if you want the data from the TIS. But a crew, has to brief, fly, and debrief as a crew.

 

[KSCessnaDriver]

With a trained three-person crew, the only time the pilit's eyeballs should come inside are for critical instruments like airspeed. Single-pilot, you have no choice if you want the data from the TIS. But a crew, has to brief, fly, and debrief as a crew.

Please don't take this the wrong way, but if I was flying with 2 guys from CAP, I wouldn't trust them with my car keys, let alone looking for traffic, even if they are pilots. I'm sorry, but my dealings with CAP, and the stories I've heard about CAP, its not filled with people I'd trust my life with.

 

[denverpilot]

Please don't take this the wrong way, but if I was flying with 2 guys from CAP, I wouldn't trust them with my car keys, let alone looking for traffic, even if they are pilots. I'm sorry, but my dealings with CAP, and the stories I've heard about CAP, its not filled with people I'd trust my life with.

No National volunteer organization is perfect. There's a definite leadership chain for a reason. Not everyone gets to be an Astronaut when they grow up.

They'd welcome a CFII, I'm sure.

Plus, any squadron can have problems. Some run well, some not so well.

The only way to fix it is locally -- volunteers who know what they're doing have to join up and do things right, or it falls apart... just like any large volunteer organization. Red Cross, United Way... all with similar "volunteer" issues. It's not a paid gig, and it's hard to get someone "fired".

But it's not hard to get someone tossed off your aircrew... no one forces anyone to fly with anyone else, really. You might get paired with someone you don't trust, but you can also get paired with someone who's as professional as the day is long, for any particular training mission. For real missions, while there's a lot of lip-service to "alert rosters" and such, the reality is... the first fully-manned crew's pilot that calls the alert officer back, is going to be told, "Go to the airport." So you can manage who you'll contact and who you'd be willing to show up at the airport at o'dark-thirty with, even if it seems like you wouldn't. You build friendships and know people's skills.

If you get known as a great right-seater who can handle the radios, charts, paperwork, and coordination of the search, or photo runs, or whatever, and also handle the additional gear on board, leaving the pilot to fly the plane -- you're going to get called by pilots who want to be ready to go flying, for example. Being good in all the seats, means lots of training, and you'll get called. Being a guy who shows up once in a while for a free flight during an exercise, means you'll probably be the guy NOT called first by anyone when the real need arises to go.

Also like many things in life, the "stories you hear" are just that. Stories. And outsiders to any organization love telling the bad stories, and rarely relate the good ones. In fact, the good stories that are worth telling, often aren't told because they'd have to come from the insiders, and because there just aren't enough people to expend resources on telling the good ones. Sure, every mission has a PIO, but they're dealing with the Press and any visitors. A really good one will write up a re-cap article for the Wing magazine. Just like the nightly news, not too much "good" news makes its way outside or to anyone who cares, because they'd rather focus on that "one story" they heard, years ago.

A safe/successful mission flown is rarely a "story-worthy" event to anyone except the crew and their Mission staff. That's just the nature of volunteerism in all volunteer organizations. A few statistics and a sound byte for the local TV news, and that'll get bumped if a dog gets run over on the highway and a TV crew was nearby.

Around here, things are pretty good... maybe there, they're not? Why not join up for a year and volunteer your services? It'll cost ya about $75 in dues (depending on if you only pay National dues, or also have local ones), and you'll have to buy a $35 polo shirt and match it with your own pair of grey slacks, black socks, and black shoes for the basic uniform. While I hate that they don't waive dues for CFI/CFIIs (they should)... they're always in need of good Instructors. Plus, one of the more rewarding parts of it is that you'd qualify very quickly to work with the Cadets, and seeing young people excited about Aviation is good for any old man's soul, really. They're motivated, have goals, and really appreciate the "Orientation" flights. Heavily experienced glider pilots are also in high demand in areas where enough people care to have gotten a Cadet glider program going. As our local head of the Glider program said when I asked who he was looking for in pilots for the Cadet rides, "I want you to be Commercially rated, confident that you are 100% in control of the glider, and if you haven't landed out or had any of the usual long-time glider experiences, you're not ready yet... before you can fly Cadets around." He said even more, but he's serious about safety in the Cadet glider program. And he and a couple of the glider instructors around here have thousands of hours in gliders... it's a serious program. Taking kids you don't know, teaching them to fly gliders for free, with their parents watching -- isn't for the faint of heart. Seeing their reaction to being soloed at a glider encampment, because they've worked hard, and they're ready -- makes it all worth it. Or so I hear. I haven't got the experience to do that yet.

Around $100 is about all it takes to get started, and you could fix all the bad behavior you care to, as a CFII. I see lots of CFI's volunteer for FAASTeam stuff, and ground courses... but not a lot volunteer time in aircraft... the few around here that do are airborne nearly constantly. If they're available, they're up with a student. And for many, it's a great way to earn a ton of referrals to their normal paid CFI job. We have a squadron of almost 90 people... if anyone asks me for local CFIs, I have a very short list that *I* trust, and a couple of the CAP guys are on it. Not all. But they get my "nod" and introductions to anyone who asks me who they should learn to fly with.

If you have the requisite hours and requirements you could be well on the way to Check Airman status in the Standardization/Evaluation role, too... And really "fix" things. The Check Airmen are the folks who really hold the keys to the kingdom, so to speak. If folks pass checkrides with them, they're on the mission roster...

Since that all sounds too much like "work", the benefits are not grand, but they're things like subsidized access to brand new or relatively brand new aircraft, depending on location, a chance to get out in your community and meet some great folks (one squadron member ran for Congress, and is on the local Fire District Board, others are prominent attorneys or other professionals, some are just techies like me, and our squadron Medical Officer, is a Vetrinarian... which seems to fit nicely since we're the "Black Sheep Squadron"... baaaaaaaa... our Vet takes good care of our health!), Wing and National conferences allow you to go and get ground training or seminars on interesting topics, etc etc etc...

I'd strongly say that most of the time when folks truly come and stay for a while, and figure out what's really going on, those "stories" they heard start to lead to the few bad apples that any National volunteer organization has. They're not worth spending much time worrying about, and you can easily avoid them unless you're the one giving them a check-ride, and in your unique position as a CFII, you could keep that bad apple from spoiling the whole batch.

C'mon in, the volunteer water's fine. And I find it much more interesting and entertaining than my previous volunteer role, which was as the President of a radio club. Volunteering in Aviation is far more fun.

There's always also other organizations like AngelFlight, and animal rescue things... but there's nothing like getting a "Find" on a real lost person, or even a "Save" lifesaving award. It takes training and effort, and a good CFII is definitely part of the necessary cogs to make the big wheel spin.

 

[KSCessnaDriver]

They'd welcome a CFII, I'm sure.

Plus, any squadron can have problems. Some run well, some not so well.

Oh, don't get me wrong, I had dealings with CAP pilots who seemed really nice, knew what they were doing, and generally seemed like good people. Good and bad apples in every bunch.

I always thought about joining something like CAP or USCG AuxAir, and told myself once I graduated college and was settled somewhere. Well, now, I got a job where I travel all the time, with the airship I'm on. Maybe some point I'll get a chance to do some work in an organization like CAP. You guys do good work. I'd always do my best listen for ELT's so I could report them, and maybe get you all some flying.