Thursday, June 19, 2008
Making ADS-B Work
The technology looks promising, but there are still unanswered questions about its implementation
|Text weather, including METARs and TAFs, are available on the FIS-B page of the Garmin MX20.|
To better understand the widespread opposition to the mandate as currently written, a quick comparison of ADS-B Out and ADS-B In is in order. The GA pilot who has only ADS-B Out will see few, if any, benefits over those provided by the current Mode-C-transponder-equipped aircraft. Those with ADS-B In, which also will automatically include ADS-B Out, will have complete access to datalink weather information, including radar images, surface observations and forecasts, plus detailed traffic information. In other words, with ADS-B In, pilots will have useful tools that greatly enhance the safe conduct of flight. With just ADS-B Out, pilots will simply be allowed to do what they’re already doing, but will have to equip their aircraft with an expensive new box to maintain the status quo. As with the adoption of any new technology, for all parties concerned, it all comes down to cost versus benefits.
If you spend the time to wade through the NPRM, the FAA’s position seems to be simple. They’ll provide all services (ADS-B In and Out) and let owners choose which version to install, but with a critical provision. Under the mandate, by 2020, owners must install at least ADS-B Out in aircraft they plan to fly in controlled airspace (in essence, this includes the majority of GA aircraft). Organizations and individuals who have studied or already used full-featured ADS-B services argue that this mandate offers no new benefits for owners and penalizes them by requiring new equipment.
“The ADS-B proposal is a good starting point for deliberation on the implementation of this cornerstone for the NextGen [Air Transportation System],” wrote Andy Cebula, AOPA executive vice president of government affairs. “However, the proposal isn’t acceptable in its current form. The implementation plan offers little benefit to GA operators. The FAA’s contract for ADS-B services leaves GA wanting; incentives are needed for ADS-B equipage.”
The AEA weighed in similarly, “The AEA, in general, supports the requirement to adopt ADS-B. However, the AEA doesn’t support this proposed regulation. The FAA has failed to offer a proposal that’s cost-effective and safety-enhancing, or even a complete proposal,” said AEA President Paula Derks. “In addition, contrary to public law, the FAA is proposing a performance standard in this NPRM that isn’t available for the public to review.”
|The ADS-B traffic display as seen overlaid on the moving map of a Garmin MX20 MFD. Shown here is a high concentration of traffic over Hartsfield-Jackson International Airport in Atlanta, Ga.|
Again, it all comes down to money. As the plan is currently written, owners will have the choice to pay a smaller amount to satisfy the requirements of the ADS-B Out mandate, or pay for a more expensive installation that will provide them with full weather and traffic information. At this time, it’s difficult to accurately project the cost for either option based on current equipment availability. But that may change very soon.
Beginning with Capstone, the avionics box at the heart of ADS-B has been manufactured by Garmin. It’s designed to handle both ADS-B In and Out signals and is called the GDL 90 UAT (Universal Access Transceiver). So far, it has been manufactured in such limited numbers that it’s very expensive, and coupled with the need for a Garmin display unit such as the GMX 200 MFD, the total installation cost has approached $20,000.
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