Input/Output: Cost of ADS-B: A First Take

Automatic dependent surveillance-broadcast (ADS-B) looks to be the future of surveillance in the National Airspace System (NAS). Although FAA has announced only a preliminary decision, ADS-B is a good bet--sooner rather than later--because of its performance advantages for both controllers and operators, as well as its economics. But what will it cost to equip the fleet? How can airlines get the most capability with the least pain?

As it happens, Mitre's Center for Advanced Aviation System Development (CAASD), a federally funded R&D center, discussed these issues at the recent Digital Avionics Systems Conference (DASC) in Arlington, Va. Using its highly granular predictive model as the basis for an initial look at ADS-B equipage trends, Mitre examined current levels of equipage and estimated future levels of equipage and modification costs. The study, no doubt, will provide fodder for both those who want an ADS-B mandate as soon as possible and those who want to push it off into the distant future. Mitre will provide more details in coming months at its Web site, www.mitrecaasd.org.

For one thing, Mitre indicates that much will be achieved through attrition and normal replenishment. In 2014, assuming no retrofits, almost half of the large air transport fleet (3,303 aircraft) would be capable of using ADS-B, either broadcast-only or full cockpit display of traffic information (CDTI). That compares with 3,406 aircraft which would not have this capability. Of course the longer one waits to equip, the longer it will take to reap the benefits. It should also be noted that "capable," in Mitre's study, means using the currently fielded DO-260 standard. If operators are required to upgrade to a new DO-260A standard, there will be an additional cost.

Not all of the 3,406 aircraft in 2014 would be equally incapable. Mitre says that 1,811 of them, in fact, would be "latent" vis-୶is ADS-B. These airplanes would have some, but not all, of the components required for ADS-B. They may be able to achieve ADS-B by adding data link, interfacing to existing equipment, or applying a service bulletin, said Kent Hollinger, the Mitre CAASD principal engineer who presented these findings at DASC. By contrast, "not equipped" aircraft like old DC-9s would require major component additions or equipment replacements. There could be as many as nine different gradations of latency.

Mitre developed "state diagrams," graphically depicting the different modification paths airlines might take to achieve ADS-B. These paths include: nonequipped to CDTI, nonequipped to broadcast-only, latent to CDTI, latent to broadcast-only, and broadcast-only to CDTI. Of these paths, the least expensive is from latent (for broadcast) to broadcast-only. For "modern," digital aircraft with integrated displays, such as the Boeing 777, the cost of the latent-to-broadcast-only route is around $16,500, according to Mitre. This modification strategy for a "neoclassic" aircraft like a B757 or B767 costs approximately the same amount. It will cost about $25,500 for a "classic" analog plane without a flight management system.

The good news for air transports is that the number of "capables" (using DO-260) would rise steadily over time--from just over 600 in 2004 to more than 4,000 in 2016. This reflects the fact that Boeing and Airbus have been equipping jets with the ability to broadcast via extended squitter for the last two years. The number of nonequipped air transport planes would decrease from almost 3,000 in 2004 to slightly more than 1,300 in 2016, as older models are retired.

But what about costs? Mitre estimates it will take $850 million to equip any remaining "stragglers" for broadcast-only in the air transport, regional and general aviation (GA) sectors if FAA sets January 2021 as the required ADS-B capability date. That's $141.3 million for air transport, $32.9 million for regional and $676 million for GA. The estimate assumes no access to airspace above FL100, into Class B airspace, and into the top 70 airports without ADS-B.

But FAA is understood to be considering a 2014 start date for Class A airspace. If so, the cost will rise, perhaps significantly, which will be an argument against it. Mitre, no doubt, is studying that, too.