ATM Modernization, Commercial

Allowing CPDLS to Blossom

By David Jensen | May 1, 2004
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You can't keep a good man down, the saying goes—and the same appears to be true with a good technology.

Hit with budget constraints, the Federal Aviation Administration (FAA) has had to make some difficult decisions lately regarding new technology programs. One program, whose advancement has been "deferred," according to an FAA statement, is controller pilot data link communications (CPDLC). The agency launched CPDLC Build 1 at the Miami air route traffic control center (ARTCC), where initial daily use of data link communications began in October 2002. Early results of the trial program, compiled by the Mitre Center for Advanced Aviation System Development (CAASD), revealed that CPDLC reduced controller workload and relieved voice communication congestion. The positive results were to serve as a springboard for Build 1A, in which the CPDLC capability was to be established at seven additional ARTCCs, beginning in 2003.

But FAA gave several reasons, in addition to budget constraints, for axing Build 1A and postponing nationwide CPDLC deployment until 2009. Five years from now the agency plans to complete installing new host computers in the 20 ARTCCs, in a program called En Route Automation Modernization, or ERAM. FAA contends that it wants to begin nationwide deployment with an ERAM-compatible CPDLC system, which would require different software from that of the Miami system.

The five-year delay is unfortunate. The CPDLC program continues to demonstrate the benefits of data link communications. The frequency time saved over the about 17 months since the program began tops 40 hours, according to Mitre CAASD figures. What's more, the innovative controllers in Miami have expanded the menu text service (used to digitally deliver advisories to pilots) to include direct route clearances. Starting in April, they planned to digitally issue profile-change clearances, which may involve altitude and speed variations, as well as heading changes. The controllers refer to these added messages as "value-added services."

Pilots "love" the direct route clearances, says an official of an airline participating in the CPDLC program. "There's no confusion. Before the service, you often had to have clearances repeated and even spelled out, and then you often had to write them down." More than efficiency, this clarity in communications also produces a key safety benefit. Since CPDLC service began, a Miami center official reports, there have been "zero corrupted messages, zero operational errors, and zero pilot deviations" while using data link communications.

"We estimate an 18 to 22 percent improvement in the amount of common errors, such as read-back errors, using CPDLC," he says. "That's pretty profound."

Eurocontrol, meanwhile, is advancing its CPDLC implementation program, called Link 2000+. One hundred aircraft owned by six airlines have signed up to participate. They are expected to generate more than 140,000 CPDLC-equipped flights annually over central and southwest Europe. In enlisting these "pioneer aircraft," Eurocontrol has met its goal in program participation.

An official with one of the participating airlines gives three reasons for Eurocontrol's success: it established a "clear roadmap," outlining how the program will progress; it showed it is committed to the program, giving airlines assurance that the investment to equip for CPDLC ultimately will reap benefits; and it offered the participating airlines an incentive: a 2 percent reduction in overflight fees. Indeed, Eurocontrol has demonstrated that to advance new technology, it is willing to both offer a "carrot," in the form of fee reduction, and occasionally use the "stick," in the form of mandates.

FAA gives disappointing user participation (about 25 airplanes compared to the 200+ sought) as another reason for discontinuing CPDLC Build 1A. The agency appears to be unwilling to wield a mandate stick and has no overflight fees to reduce. Nevertheless, it could "incentivize" aircraft operators to participate with, say, a selective reduction in the fuel tax. The agency must establish a road map for the program and stick to it, to assure confidence in the program's future. Airlines have shown that they recognize CPDLC's benefits and will equip. But for true benefit, data link communications must expand. A more robust system, with an expanded message set and the capability for pilots to transmit data link responses without a voice communication backup, should be established in Miami. And, prior to 2009, more ARTCCs should be equipped for CPDLC. Incentives would no doubt expedite airline participation, though carriers would probably prefer a commitment by FAA to expand the program. They recognize CPDLC is a technology too good to keep down.

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