Start of datalink test buoys ATC modernization efforts

 - May 19, 2008, 6:08 AM

Maneuvering over Southern Florida and through busy Miami airspace on a classically warm and convective Thursday in March, an FAA test airplane spent several hours aloft exchanging more than 100 routine messages with ATC–all without the pilots or controllers having to utter a single word.

The flight trial was the first demonstration in crowded airspace and under actual ATC operating conditions of controller-pilot datalink communications (CPDLC), an FAA modernization program intended to replace voice communications between pilots and ground controllers with two-way text messaging.

Perhaps most gratifying about this inaugural test flight was not that the advanced datalink equipment aboard the FAA Convair 580 operated as advertised, but rather that the test took place at all.

The successful Miami evaluation cleared another hurdle on the way toward the FAA’s eventual goal–the nationwide availability of operational datalink service, the first phase of which is scheduled to begin in September in Miami as part of the CPDLC Build 1 program. For a number of weeks this past winter, however, there were serious doubts that the March test would occur on schedule, with program heads predicting at least a year-and-a-half delay. Only a series of last-minute maneuvers by major airlines–whom CPDLC is designed to benefit–allowed the program to go ahead without postponement.

After September 11, support for the CPDLC program initially lost momentum as U.S. airlines became focused on assessing the toll that deep revenue losses were taking on the industry. As carriers desperately sought to staunch the financial hemorrhaging, modernization goals understandably were placed on hold. In meetings and consultations last October, the FAA decided to put the CPDLC on the back burner for the time being. In the months since then, the airlines have shown signs of rebounding, leading to a decision by American Airlines, the CPDLC test leader, to move forward. With support for CPDLC again running high, the FAA put the program back at the forefront of technologies designed to overhaul the nation’s ATC infrastructure.

American Steps Up to the Plate

For a brief time late last year while the major airlines reeled there were suggestions that the business aviation community might be recruited to test CPDLC in American Airlines’ stead, and that a large fleet such as NetJets could take over where the airline left off. However, now that American is again putting its financial and operational resources behind the program, the plan to use bizjets for CPDLC testing has quietly faded away.

Instead, CPDLC will remain the purview of the major airlines, a program focused on increasing airline capacity at major hub airports by streamlining communications. The benefits, however, will translate into fewer delays and better efficiencies for private operators as well. NBAA, for one, is encouraging its members to support CPDLC and other modernization efforts, which hold the promise of easing gridlock at major metropolitan business aviation hubs.

During the March 7 trial in southern Florida, the FAA test airplane used VDL-2 (VHF datalink-Mode 2) avionics built by Rockwell Collins to communicate with FAA ground systems. A regional network of VDL-2 ground stations built and deployed by Arinc linked the air and ground portions of the system. All told, more than 50 such stations have been installed at high-density airports around the country, with hundreds more slated to come online in the coming months and years.

As part of the FAA’s Free Flight Phase II program, CPDLC is being designed initially for rudimentary exchanges between pilots and controllers, such as ATC handoffs, altimeter settings and acknowledgement of pilots’ initial calls, with the goal being to slash the number of controller-pilot radio transmissions. Trials with CPDLC-equipped American Airlines Boeing 767s and 737s and Miami Center controllers are scheduled for next month, and are to be followed by the debut of operational CPDLC service in September. A national rollout of the second iteration of the system–incorporating more functionality, including ATC clearances–is scheduled to begin in December 2005. In all, the FAA will deploy Build 2 at 20 centers nationwide.

The Miami VDL-2 architecture is the first permanent VHF air-to-ground network that fully meets the standards of the ICAO-backed Aeronautical Telecommunications Network (ATN) protocol. The flight validated years of development and testing that took place in laboratories and simulations, and paves the way for what most agree will be the concept’s real challenge this summer. With the introduction of CPDLC, airlines are expected quickly to begin equipping with VDL receivers, which are generally accepted to represent the future form of aviation transceivers. Further along, the FAA plans to require equipage of VDL-3 avionics for the so-called Nexcom program, which will extend CPDLC to all segments of aviation starting in 2009.