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AOPA strongly challenges FAA's ADS-B planAOPA strongly challenges FAA's ADS-B plan

AOPA strongly challenges FAA’s ADS-B plan

By AOPA Communications staff

AOPA on March 3 raised significant concerns in its formal comments on the FAA’s plan for implementing ADS-B (automatic dependent surveillance-broadcast), the backbone technology for the Next Generation air traffic control system.

“No one has championed ADS-B more than AOPA,” said AOPA President Phil Boyer. “After all the time, effort, and energy that AOPA has put into promoting ADS-B and working closely with the FAA to make sure it develops in a way that’s useful to general aviation, I’m deeply disappointed with the agency’s implementation plan.”

The FAA proposal requires that all aircraft operating in Class A, B, and C airspace, plus all airspace above 10,000 feet msl, have to be equipped with ADS-B datalink equipment that transmits the aircraft’s position, altitude, speed, and aircraft ID.

“But the FAA fails to provide an affordable transition from today’s radar-based system to tomorrow’s satellite-based system,” continued Boyer. “So we have no choice but to urge the agency go back to the drawing board.

“If there is any good news in the FAA plan, it is just this: Pilots still have 12 years to comply.”

The bottom line

“The ADS-B proposal is a good starting point for deliberation on the implementation of this cornerstone for NextGen,” wrote Andy Cebula, AOPA executive vice president of government affairs, in the association’s comments. “However the proposal is not acceptable in its current form.

“The implementation plan offers little benefit to general aviation operators. The performance requirements for ADS-B are excessive for low-altitude operations. The requirement to keep Mode C transponders is unacceptable. The FAA’s contract for ADS-B services leaves general aviation wanting; incentives are needed for ADS-B equipage.”

Unfulfilled promise

ADS-B-equipped aircraft update and digitally broadcast their GPS-derived position once every second to ground stations and other similarly equipped aircraft. The capability is known as ADS-B Out.

Using a universal access transceiver (UAT) developed specifically for use in GA aircraft, ADS-B has the potential to provide pilots with in-cockpit displays of weather and traffic (known as ADS-B In).

“ADS-B In provides value-added information that improves pilot safety and efficiency,” wrote Cebula.

The association has maintained for nearly a decade that the best way to encourage GA aircraft owners to purchase ADS-B In avionics is to supply all available graphical and textual real-time weather, airspace, and traffic data in the cockpit at no additional charge.

“That is why AOPA is concerned the FAA’s contract with ITT limits the number of traffic targets broadcast via traffic information service-broadcast (TIS-B). This means that pilots will not be able to see the locations of all known traffic, reducing the effectiveness of TIS-B for the safe and efficient operation of general aviation aircraft.

“Ironically, this is a degraded level of service when compared to the Safe Flight 21 East Coast testbed, which has been in operation for several years.”

A throwback, not a leap forward

ADS-B is actually built around two incompatible technologies: general aviation’s UAT and the airline-preferred Mode S transponder with 1090 extended squitter. The dual datalink system raises safety issues that can be resolved, commented AOPA, by providing ADS-R (rebroadcast capability) at all airports where pilots may operate on either of the two links. ADS-R receives data from each frequency and retransmits it on the other frequency through a ground relay.

The FAA’s proposal for implementing ADS-B basically emulates today’s radar coverage instead of taking advantage of the system’s lower infrastructure cost and expanding coverage. This results in, wrote Cebula, “little more than a warmed-over version of the Mode S transponder proposal from the 1980s.

“This approach to implementing ADS-B raises serious questions about the scope and magnitude of the mandate.”

FAA, airlines main beneficiaries of proposal

Throughout ADS-B’s development, AOPA worked in partnership with the FAA to identify the right combination of features and free benefits to entice GA aircraft owners to invest in the new avionics, as had happened with the global positioning satellite system where, without a mandate, more than 90 percent of GA owners now use GPS.

However, the system as proposed does not require the contractor, ITT, to provide those benefits for free.

The FAA’s own data show that the biggest cost savings would benefit the agency itself and the airlines. But the proposal’s mandate for GA to equip with ADS-B Out without providing ADS-B In benefits, coupled with the mandate to maintain Mode C transponders rather than replacing them with ADS-B equipment, means a more expensive system for GA that is little better than the current system.

Additional cost factors for GA aircraft owners include a requirement for dual ADS-B antennas and higher transmit power requirements than are necessary for low-altitude operations, where the overwhelming majority of general aviation pilots fly.


AOPA has been a proponent of ADS-B and its potential benefits from the system’s inception and will continue to be actively involved in its implementation.

AOPA is the only GA association to have dedicated a staff position to advanced technologies like ADS-B and has been an active partner with the FAA since the first ADS-B testbed project, Capstone, began in Alaska in 2000. As part of Capstone, AOPA hosted an ADS-B ground station at its Frederick, Md., headquarters for the FAA and provided airborne demonstrations to pilots, senior FAA management, state aviation directors, members of Congress and their staffs, and several international delegations.

The association also promoted the potential benefits of ADS-B to its members with numerous articles in AOPA Pilot , the world’s most widely circulated aviation magazine, frequent updates on AOPA Online, and regular communications in the weekly AOPA ePilot electronic newsletter, which reaches more than 300,000 subscribers, or more than half of the U.S. pilot population. In addition, AOPA’s Boyer narrated a video on ADS-B for the FAA, and AOPA has hosted FAA presentations and seminars on ADS-B at the past seven AOPA Expo annual conventions.

“However,” concluded Boyer, “the suggested rule is not acceptable in its current form. It is a high-cost plan that offers few if any benefits for general aviation.

“We believe the current proposed rule is so unworkable that the FAA needs to abandon plans to publish a final rule, go back to the drawing board, and issue a supplemental notice of proposed rulemaking.”

March 4, 2008

AOPA Communications staff

Topics: ADSB

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