Let's face it - aviation can be a befuddling thing. To help you wade through the mess, I'm going to start a recurring series on the blog: Demystifying General Aviation. This series will be aimed at boiling down complex or confusing issues pilots are likely to see in the near future, and I'll follow a who, what, where, when, why, and how structure (in some order) to try and sort things out.
To kick things off, let's talk about ADS-B.
What? Why?
If your first reaction to this title was to google "ADS," we're not talking about Advanced Drainage Systems or Astrophysics Data Systems or what looks like some kind of military equipment acquisition service (handy as that may be). We're talking about Automatic Dependent Surveillance-Broadcast, a "a cooperative surveillance technology" that lets your plane tell ATC where it is rather than vice versa. If your first thought is "so what?", think again: you will have to install this stuff by 2020 if you want to keep flying.
ADS-B is divided into two discrete components, appropriately termed ADS-B in and ADS-B out. ADS-B out is the important one from a traffic control perspective: it reports your position, velocity and altitude to ATC (and anyone else who's listening to the signal) once per second. ATC no longer has to compute these variables, though radar stations will still be able to do so for confirmation. This may not seem like a huge benefit to pilots, but it should increase safety by adding a redundant tracking system, reducing ATC workload, and automating the process. The system depends on everybody buying in (sound familiar?), so subject to a few narrow exceptions you'll probably have to fit your plane with an approved ADS-B out device.
Equipping your aircraft with ADS-B in is optional, but comes with two big benefits. First, it lets you join the "anyone else who's listening to the signal" club. You receive the ADS-B out signals from other planes in the area and a Traffic Information Services-Broadcast (TIS-B) signal from ADS-B Ground stations, which give you real-time traffic without any radio work from ATC. *1 Second, it lets you receive Flight Information Services-Broadast (FIS-B), which broadcasts NEXRAD radar, METARs, TAFs, TFRs, AIRMETs, ground weather conditions, and other information without a paid subscription. *2
This basically depends on where you plan to fly. If you're going to be up in the flight levels (> FL180) or you plan on flying internationally, you will need a 1090 (ES) out unit. If you don't need to do either of those missions, you will be fine with a 978 (UAT) unit.
Remember, though, that ADS-B in and out are two completely separate functions that can be performed by independent devices. This means you can have any combination of frequencies: 978 Out, 978 Out/In, 978 In, 1090 Out, 1090 Out/In, or even 1090 Out/978 In.
Only a few thousand of the 120,000 or so planes that will be affected by this rule have actually been fitted with ADS-B out, which means 100 or more installs will have to be completed per day from now to 1/1/20 if everybody's going to keep flying. This isn't going to happen, of course – that would be a 25-fold increase over the current installation rate, according to Paula Derks of Aircraft Electronics Association, testifying before the House of Representatives Committee on Small Business last week.
Some of this hesitation may be warranted. The FAA's reputation for sticking to deadlines is less than sterling, and the cost-benefit ratio is not necessarily better than the existing technology for pilots. Speaking for AOPA, Bob Hepp reported that to equip his company’s 39 aircraft would cost about $312,000. He added that uncertainty about FAA actions makes general aviation owners reluctant to invest in new equipment, and that the benefits of ADS-B for pilots have not been made clear by the agency. Rick Durden recently reported that pilots on the financial edge of still being able to afford to own and fly their airplanes have been telling him ADS-B compliance is just going to be too expensive, so they’ll sell their airplanes in 2019 (if they're still flying by then). "On the surface that logic makes sense," says Durden, "However, it means that those procrastinators may pay a big price for delaying and then either complying or selling non-compliant airplanes...Now may be the right time to take care of ADS-B compliance."
I think Rick's right on track. This regulation isn't going away anytime soon, and now is probably the cheapest time to jump on board. At the same House Committee Hearing, Tim Taylor, President and CEO of Free Flight Systems, Inc. testified:
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*1 TIS-B is only broadcasted to your ADS-B in unit if you are also broadcasting ADS-B out.
*2 If you currently use XM weather, this will feel familiar, but keep in mind that it is based on ground stations rather than more universal satellite readings.
*3 There are a few exceptions as described in the "Who?" section.
*4 I know that sounds confusing, but so does everything else about Class E. Fortunately, like the visibility minimums, they start to make sense if you think about them for a second.
*5 FAR 91.225(g)(2)
*6 The Stratus is a popular ADS-B in receiver - any other brand will offer the same capabilities shown in this chart. Others include the the Garmin GDL 39 and Dual XGPS 170.
Further Reading: Thanks to the following pages for much of the information in this post.
"But wait, isn't that what my transponder does? Isn't that why they randomly make me push my little IDENT button?"Sort of, but ADS-B takes it to another level. Your transponder works in conjunction with ATC's primary radar (the waves that actually bounce off your airplane's skin) by responding to "interrogations" from ATC's secondary radar system. As you probably know, the IDENT button makes you light up on their tracking screen, Mode C and S transponders send them your pressure altitude, and your assigned squawk code helps them tell you apart from other aircraft. These data give ATC a pretty good idea of who and where you are, but the controllers are still fundamentally tracking you and the system involves a lot of double- and triple-checking to make sure pilots are doing their part to keep the system running smoothly. Aircraft equipped with ADS-B flip this around by determining their own location and sending it to ATC's NextGen or European controllers' SESAR. Transponders improved radar; ADS-B is replacing it (but don't worry - radar is still around for backup). All airplanes covered by the rule must also equip WAAS GPS, but that's another article in and of itself.
ADS-B is divided into two discrete components, appropriately termed ADS-B in and ADS-B out. ADS-B out is the important one from a traffic control perspective: it reports your position, velocity and altitude to ATC (and anyone else who's listening to the signal) once per second. ATC no longer has to compute these variables, though radar stations will still be able to do so for confirmation. This may not seem like a huge benefit to pilots, but it should increase safety by adding a redundant tracking system, reducing ATC workload, and automating the process. The system depends on everybody buying in (sound familiar?), so subject to a few narrow exceptions you'll probably have to fit your plane with an approved ADS-B out device.
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| Credit: iPad Pilot News (click for the full article). |
Can I just buy one of those cheap(er) portable doohickies?Nope - at least not in the long run. There are several portable ADS-B in receivers out there that will connect with your iPad, other tablet, or even mounted avionics to give you the benefit of ADS-B in without the high installation costs of a fixed unit. *6 But remember: the rule says you need an approved ADS-B out unit, and those have to be panel-mounted. The FAA has hinted that they are in the early stages of potentially allowing a portable unit for gliders, but even that seems like an outside chance at this point. You're certainly free to buy a portable in unit, but if you're going to be purchasing a panel-mounted out unit anyway you might want to think about doing an all-in-one. The average panel-mounted in/out unit is going to run you several thousand dollars, though, so it may be worth riding the market to try and grab one soon (but not too soon).
So the FAA is just mandating that everybody gets the same equipment that lets all planes talk to each other?Of course not - that would be too easy. There are actually two frequencies of ADS-B (both in and out): 1090 MHz, known as ES for Extended Squitter, and 978 MHz, known as UAT for Universal Access Transceiver. Which type you'll need depends on your airspace objectives (see chart below). The 1090 does squit (whatever that means) further than the 978, which can be a benefit even for lower altitude pilots. Each frequency can only talk to other units of the same frequency, so UAT Cherokees probably won't pick up descending ES Citations unless they're getting the TIS-B from a ground station. *1 As a bonus absurdity, while either frequency will pick up TIS-B, only the 978 (UAT) units will pick up FIS-B (weather).
Where?
But I avoid ATC like the plague...do I really need this?Not necessarily. You'll need ADS-B to fly in Class A, B, or C airspace, plus Class E airspace above 10,000 feet mean sea level (unless you're within 2,500 feet above ground level). *3 *4 The ADS-B requirement does not apply to the rest of Class E (under 10,000 MSL or within 2,500 AGL) or Class G airspace. This means he FAA won't make you put this technology on board if you promise to only fly your Taylorcraft on clear days away from towered airports. You can request a deviation from the rules for your non-compliant aircraft, but you have to do so at least an hour ahead of time and there's no guarantee you'll get permission. *5 If you plan on using your plane to do any serious transportation, you'd better start thinking about not if but when to make this jump.
So which one do I need?
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| Credit: Air Facts Journal |
Remember, though, that ADS-B in and out are two completely separate functions that can be performed by independent devices. This means you can have any combination of frequencies: 978 Out, 978 Out/In, 978 In, 1090 Out, 1090 Out/In, or even 1090 Out/978 In.
Do they even have this stuff out in my neck of the woods?Probably. Click here and go down to "ADS-B Coverage" for a current map of ground stations, or here to download a current list in spreadsheet form. Line-of-sight range for ground stations is about 150 nautical miles, so while there are definitely still areas where pilots will be out of range they should be few and far between in medium- to long-range transit.
Who?
As laid out above, this rule will affect anyone who plans to use an aircraft to move through any kind of controlled airspace. It does not discriminate between ratings, types of aircraft, or any similar factors. If you don't need a Mode C transponder to fly your routes today, you may be exempt.
How?
So which one of these things should I actually get?The rule is all about ADS-B out, so make sure you've got your bases covered there. Once you've got that decided, figure out which ADS-B in capabilities you're willing to pay for and select a unit or combination of units to match. Here's a decision tree to help you through the process:
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| Click for a larger version. You may print or copy this graphic for personal use. You may republish it if you reference this blog post. *Edited to correct an error and change background to solid white. |
Can I just upgrade my transponder?For the most part, no, but if you sprang for a higher-end Mode S transponder you may be in luck. The FAA borrowed the 1090 MHz number from the current Mode A/C/S transponders so ATC could retrofit their current system to receive this new kind of transmission over an old radio band. To oversimplify, Mode S + WAAS GPS ≈ ADS-B. That means transponders like the Garmin GTX 330 can be converted to 1090 (ES) ADS-B out units by upgrading the software and adding a WAAS GPS unit. I'm not going to go through a big list of which units can or can't do this, but it's worth asking your avionics techie about and could save you some cash.
When?
What is with this newfangled technology anyway? Nobody told me!
The FAA told us this requirement was coming in a final rule back in 2010 and codified it in an FAR amendment later that year, so consider yourself officially warned. The way the rule is worded, you'll be unable to operate an aircraft in controlled airspace after January 1st, 2020 unless you have an approved ADS-B out unit on board.
Can I put it off for awhile?Sure - everybody's doing it. Then again, like most mob behaviors you experienced in junior high, that doesn't necessarily make it the best course of action.
Only a few thousand of the 120,000 or so planes that will be affected by this rule have actually been fitted with ADS-B out, which means 100 or more installs will have to be completed per day from now to 1/1/20 if everybody's going to keep flying. This isn't going to happen, of course – that would be a 25-fold increase over the current installation rate, according to Paula Derks of Aircraft Electronics Association, testifying before the House of Representatives Committee on Small Business last week.
Some of this hesitation may be warranted. The FAA's reputation for sticking to deadlines is less than sterling, and the cost-benefit ratio is not necessarily better than the existing technology for pilots. Speaking for AOPA, Bob Hepp reported that to equip his company’s 39 aircraft would cost about $312,000. He added that uncertainty about FAA actions makes general aviation owners reluctant to invest in new equipment, and that the benefits of ADS-B for pilots have not been made clear by the agency. Rick Durden recently reported that pilots on the financial edge of still being able to afford to own and fly their airplanes have been telling him ADS-B compliance is just going to be too expensive, so they’ll sell their airplanes in 2019 (if they're still flying by then). "On the surface that logic makes sense," says Durden, "However, it means that those procrastinators may pay a big price for delaying and then either complying or selling non-compliant airplanes...Now may be the right time to take care of ADS-B compliance."
“…the idea that has been suggested by some that equipage is going to get cheaper as we get closer to the deadline is misleading and a major reason for delay. The prices we are offering for equipage now are artificially low. FreeFlight Systems is making high-volume purchases and we have reduced our margin expectations to get products in the market at an acceptable price point. As volumes start to go up, we will not be able to hold these low prices.”Tim obviously has a vested interest in pilots jumping on the bandwagon, but he's not alone and he's not lying. You're free to keep procrastinating, but it'll cost you in the end. Start thinking about it now, and if you're going to Oshkosh, you may be able to win one of Tim's units for free anyway.
But you forgot X! I still have questions!Well cripes - I'm not a savant. There is a lot out there that I didn't cover, and that's going to be another theme of these posts by necessity. Feel free to contact me by email or leave a comment below. There are also a lot of resources out there from manufacturers with some helpful (if a little pitchy) information. Check out Garmin's for starters.
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*1 TIS-B is only broadcasted to your ADS-B in unit if you are also broadcasting ADS-B out.
*2 If you currently use XM weather, this will feel familiar, but keep in mind that it is based on ground stations rather than more universal satellite readings.
*3 There are a few exceptions as described in the "Who?" section.
*4 I know that sounds confusing, but so does everything else about Class E. Fortunately, like the visibility minimums, they start to make sense if you think about them for a second.
*5 FAR 91.225(g)(2)
*6 The Stratus is a popular ADS-B in receiver - any other brand will offer the same capabilities shown in this chart. Others include the the Garmin GDL 39 and Dual XGPS 170.
Further Reading: Thanks to the following pages for much of the information in this post.
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