The third reason our transponders won't be going anywhere soon is the existence of TCAS and TCAS II traffic and collision avoidance gear, not to mention the wide variety of general aviation traffic advisory equipment, such as L3's popular SkyWatch product, all of which rely on transponder returns to function. While traffic utilities are advisory in nature and optional for GA, TCAS is mandated for air carriers. The cost of making all existing TCAS and traffic advisory devices compatible with ADS-B technology, even if doable, would be very high.
Costs, Collisions and Coverage
As program details have emerged during the last few years, the general industry mood about ADS-B has changed from optimism to widespread skepticism, for several very good reasons.
Perhaps the biggest problem with ADS-B is that we're going to have to pay for it. For years the FAA seriously considered underwriting the cost of installing a basic ADS-B box in all of our airplanes but at some point rejected the idea for budgetary reasons. The idea, according to a couple of insiders with whom I spoke, is not dead. Even in the wake of the final rule being published, the FAA was still floating the idea of subsidizing equipage. As it stands today, though, we'll have to buy our own ADS-B hardware and pay to have it installed.
That wouldn't be such a bitter pill to swallow if ADS-B did more for us, but at this point, it offers few benefits.
The main benefits that the FAA touts for ADS-B Out, including improved search and rescue and enhanced flight following, are hardly the kinds of features that will cause owners to rush out to equip their airplanes with expensive ADS-B equipment.
There's not much ADS-B equipment available right now, and what is out there is quite expensive. But the FAA hopes that, over time, a competitive marketplace will emerge with much lower cost ADS-B equipment available. Today, owners with the most advanced equipment, specifically Mode-S transponders, will likely have the cheapest road to being ADS-B compliant.
Another concern is security. Unlike existing radar sites (which, by the way, will not all be going away under the newly adopted regulation), ADS-B doesn't see any airplanes at all unless they're broadcasting, so in areas without conventional radar, non-ADS-B airplanes will be invisible to ATC. Without primary radar detection (which requires a spinning dish), there would be nothing preventing an intruder from simply turning off his ADS-B gear and flying invisibly through the airspace.
And the threat of midair collisions, due to the dual-link architecture, continues to be a concern. AOPA has asked the FAA to rebroadcast ADS-B at all general aviation airports to mitigate that risk, though the FAA appears to have neither the funding nor the will to do that.
While the challenges and costs of ADS-B loom large right now, there is hope that the technology will provide more benefits than might seem likely today. And there's little doubt that rule will create new markets and products.
Strangely enough, one potential bright market is with handheld and portable devices. Since the ADS-B signal is public, it stands to reason that manufacturers should be able to design panel-mount or portable devices that would receive the signal and display its free traffic and weather information on a portable display. Indeed, a couple of small companies are already doing just that. But it's not that simple, unfortunately. The FAA has decided, apparently in order to promote participation in ADS-B, to remove some of that value. Currently it is broadcasting traffic to receivers only within a certain distance of participating aircraft. So even if an airplane had an ADS-B receiver, unless it had ADS-B Out, the pilot would not necessarily see traffic near it, making the traffic function of ADS-B all but useless. The matter is far from settled. It's not clear that the FAA has the legal right to pull the plug, effectively speaking, on this traffic data, and alphabet groups continue to pressure the FAA to free up the data.
It's also likely that a number of combination-technology ADS-B products will emerge during the next few years. One can imagine the demand for combination UAT/1090ES boxes that would receive data from all participating ADS-B aircraft even when not in the vicinity of a rebroadcasting ground station. And combination ADS-B/GPS and even ADS-B/GPS/air-data devices are a natural too, especially for aircraft not yet equipped with approved GPS.
Our advice at this point with ADS-B is to wait and see what kinds of products become available over time. There's simply no compelling reason to equip right now. Indeed, those operators who wait even a few years are likely to be rewarded with better, more capable and cheaper ADS-B solutions.
ADS-B at a Glance
What It Is: ADS-B is simply a new-technology transponder-like device. It tells ATC (and ADS-B airplanes) where we are.
What It Does: With ADS-B Out, we send our position and flight data to a ground station that relays that data to ATC's "radar" screens.
ADS-B Out: The mandated ADS-B is called "ADS-B Out" because it sends its signal out to ATC. This is what we're all going to be required to have by 2020.
ADS-B In: ADS-B In is what we'll get with an ADS-B receiver and display (either a dedicated display or, more likely, an MFD with an ADS-B function). With ADS-B In, we'll be able to get traffic through the CDTI (cockpit display of traffic information), weather and, potentially, more.
How It Works: The ADS-B transmitter in our airplane broadcasts (that's the "B" in ADS-B) our GPS position and more, which ATC receives though a series of ground receivers. ADS-B receivers are hooked up to ATC to give controllers the big picture. Because the FAA's ADS-B system relies on dual technologies, UAT and 1090ES, there are four systems at work, UAT, 1090ES and rebroadcasts of both of those systems. As pilots, we get the information directly from airplanes using the same kind of technology as we have and from all airplanes when we're in range of a ground station.
What the FAA Gets: The feds get hundreds of "radar" sites that are a lot less expensive for the FAA to install and maintain than radar dishes are. The FAA stands to save a fortune in the deal, probably billions over time, by gradually shutting down more than 300 radar sites. The feds also get greatly improved position information on all of us. Make no mistake: ADS-B makes sense for the FAA.
What the Airlines Get: The hope is that commercial operators will get reduced separation, especially on oceanic routes, fuel savings due to better routings, better traffic advisories and, ultimately, more arrivals. It's potentially a huge cost benefit to the airlines. While many in the airline industry are skeptical or still on the fence about the benefits, the FAA seems convinced that the potential cost savings are both real and substantial.
What It's Going to Cost: This is a bit of a guess, as there are no compliant products right now, but based on what equipment is out there, it will likely cost $5,000 for a basic ADS-B Out box with a single antenna to as much as $30,000 or more for a dedicated ADS-B In box with a display and with dual antennas. If you've already got a Mode-S transponder, as the airlines do, you might be able to convert your Mode-S transponder for as little as $1,000, though, ironically, it's going to cost the airlines a lot more than that to make the transition. Over time it's almost certain that the costs will come down, but for those without Mode S, it's unlikely that equipping will cost any less than a few thousand dollars in equipment and installation costs.
How Compatible It Will Be: While the airlines and their 1090ES system will likely play well worldwide, unfortunately it looks as though operators with UAT-based ADS-B systems won't be compliant with ADS-B requirements in either Canada or Mexico, or through much of the Caribbean. There remain some sticky international problems to be ironed out there.