On March 10 next year the FAA is expected to issue its final rule covering mandatory equipage of ADS-B avionics, and agency officials are tight lipped about what, if any, changes will be made to the original draft rule offered for industry comment early last year. At that time, the agency’s proposal met with almost unanimous rejection across the aviation community, from general aviation to the airlines, causing the FAA last fall to establish a special industry advisory committee to develop alternative recommendations. While the committee is still meeting, there have been few hints about whether, in fact, much will change.

Nevertheless, the community at large has a wish list, topped by the hope that the FAA will offer incentives to aircraft owners who simply cannot make a positive business case for ADS-B out. As one pilot put it, “We are supposed to be moving to a performance-based ATC system, with control restrictions if you aren’t properly equipped. But I only fly VFR at a couple of thousand feet, so what good is ADS-B for me, or for ATC?” The Europeans recognize this problem: at the ATC Global conference in Amsterdam in March, a Eurocontrol official told AIN, “Our mandatory ADS-B program exempts aircraft [with an mtow of less than] 12,500 pounds that cruise below 250 knots.” It seems unlikely, however, that the FAA will follow Europe’s lead.

The ADS-B requirement for Waas is also drawing questions. While there are reportedly more than 40,000 Waas receivers currently in general aviation use, many more airplanes have straight GPS units, and the added cost of replacing them with Waas receivers is clearly a disincentive to installing ADS-B. However, this impact could be lessened by newer, lower-cost ADS-B in and out units such as those being developed by Sandia Aerospace in Albuquerque, N.M. Sandia’s president, Dennis Schmidt, told AIN that his company is looking at base prices around $3,000 to $3,500, not including Waas and display, and expects to introduce its units at EAA AirVenture Oshkosh in July.

A larger issue–that of the continuing future availability of full GPS service itself–risks overshadowing ADS-B’s promise and, some suggest, could even see the FAA’s 2020 mandate extended.