Guy Norris/LOS ANGELES
For years, the US Federal Aviation Administration has been accused of dragging its feet over the implementation of satellite-based communications, navigation and surveillance/air traffic management (CNS/ATM) techniques in airspace under its control in the North and Central Pacific regions. Now advances are under way that may silence its critics.
The FAA is using advanced CNS/ATM systems to reduce lateral separation to 92km (50nm) in the Central and Eastern Pacific regions, mostly covering US-Hawaiian routes. On 24 February, the FAA, in conjunction with other RVSM task force members in Australia, Fiji, Japan, New Zealand, Papua New Guinea and Tahiti, is to implement reduced vertical separation minima (RVSM) throughout the Pacific. Capacity is expected to be dramatically increased by cutting vertical separation from 2,000ft (600m) to 1,000ft between 29,000ft and 30,000ft.
"There is plenty of airspace, but the problem is that everyone wants to operate in the same airspace, at the same speeds, in the same direction and at the same time of day," says FAA programme director for air traffic planning and procedures Jeff Griffith. "So this is what we're trying to do."
The improvements could be timely. The Pacific Rim airlines are recovering after Asia's economic turmoil and air traffic levels across the world's largest oceanic expanse are expected to surge in the early 2000s. The fragmentation seen on the North Atlantic in the 1990s is expected to emerge in the Pacific, too, with the increasing frequency of new big twins such as the Airbus A330 and Boeing 777 families. The result will almost certainly be more competition for the same airspace.
"All our initiatives are user-driven," says Roberta Leftwich, FAA manager of oceanic operations and procedures. RVSM on the Atlantic has yielded annual fuel-related savings of $32 million, she adds. Overall, the introduction of reduced vertical and lateral separation on the Pacific routes is expected to produce fuel savings of about 1%, which, over the longer ranges involved, equates to two or even three times the dollar savings on the North Atlantic.
The FAA began its attack on Pacific separation standards in April 1998 when it introduced lateral separation levels of 92km on the North Pacific for aircraft meeting RNP10 required navigation performance limits. This requires navigational performance to stay within 18km of track centreline 95% of the time. The same reduced minima were also introduced on the Central Pacific sectors in December of that year. "RNP is a lateral path-keeping requirement, and throughout the Oceanic FIRs [Flight Information Region], we will be using RVSM separation standards," says Leftwich. Aircraft not approved with the appropriate RNP will not be allowed into "RVSM stratum" says Leftwich, unless they are on humanitarian or military missions, or have permission.
Datalink and FANS-1
The tools of the trade that allowed the process to begin are based on the Future Air Navigation System-1 (FANS-1) package developed initially in the mid-1990s by Honeywell and Boeing in association with the FAA, satellite communications and datalink service providers and airlines.
FANS-1 applications include controller pilot datalink communication (CPDLC) - a key aspect of the FAA's Free Flight initiative. The FAA has found CPDLC easier to implement across the wide Pacific than on the more crowded domestic network, where its introduction is running up to six years behind schedule. CPDLC has been in operation at the Oakland and Anchorage air route traffic control centres (ARTCCs) since 1995, and is being inaugurated at the New York centre.
CPDLC is being developed to form the basis for communication between pilots and air traffic controllers, as it is faster and more reliable than analogue voice communications, and alleviates radio-frequency congestion. The FAA's government-industry CPDLC team includes ARINC, Boeing, Eurocontrol and Rockwell Collins. American Airlines has become involved by committing to equip Boeing 767s with modified radios to participate in Build 1 CPDLC trials at the Miami, Florida, centre from June 2002. The year-long test will use VHF datalink Mode 2 (VDL Mode 2), as will the subsequent Build 2 CPDLC standard, which will offer oceanic communications. Implementation is planned from December 2004.
Thanks to FANS-1 and CPDLC, the FAA has been able to develop and inaugurate a tactical oceanic control system called DARP, or dynamic aircraft route planning. This was initiated on Pacific routes between Australia, New Zealand and the USA last April. It allows aircraft to be rerouted according to weather conditions.
New equipment needed to support the further development of FANS-1 in the Pacific was gradually introduced throughout last year at Oakland centre. This includes the installation of an updated oceanic computer system and a new Raytheon multisector oceanic datalink. This provides VHF and satellite digital-text communication coverage of all seven Pacific oceanic airspace sectors, says Leftwich. Further modernisation of the three big oceanic ARTCCs is planned this year. Three teams are competing for the work, led by ARINC, Nav Canada and Lockheed Martin. Other options, including five- to eight-year leasing contracts on CNS/ATM equipment, are under study.
SITA, meanwhile, has begun work under a recently awarded one-year contract to provide FANS-1 datalink communication services to the three ARTCCs. SITA, which supports similar FANS-1 datalink services to the air traffic service providers of Australia, Fiji, Hong Kong, India, Singapore and Tahiti, won the contract because it offered to save the FAA up to $6 million. It was able to promise big savings because it proposed a managed data communication service at fixed cost, rather than the traditional per-message basis. Eurocontrol also uses the SITA Aircom network for FANS-1 communications in its ongoing PETAL-II datalink trials.
A second major plank of the FAA's Pacific control strategy is built on automatic dependent surveillance (ADS), the second key FANS-1 application and something in which SITA could become closely involved should its contract be extended. Because of its greater potential positioning integrity, the satellite-based ADS system is expected to lead to even greater airspace use from 2003.
To take advantage of ADS potential, the FAA is developing 92km and 55km separation criteria. It is talking to the International Civil Aviation Organisation to establish standards to reduce separation to 55km laterally and longitudinally based on RNP4 (within 7.4km of centre of track 95% of the time) performance levels. "We will need to go to 50nm longitudinal before that, and we will require ADS to do that," says Leftwich. A reduction in time-based minima will be developed in parallel, adds the agency. These are set at 15min apart in trail, or 10min minimum separation with matching Mach speed. "We're working on bringing that below 10min," says Leftwich, who acknowledges that the in-trail tests using the TCAS traffic alert and collision avoidance system showed the system "can be used for good advantage".
The further reduction to 92km longitudinal separation is being implemented in two stages, the first set for later this year. Requirements for the first stage will be the ability to send positioning reports every 30min to enable 92km minima while climbing or descending through the same level as the nearest other aircraft. "Phase 2 depends on ADS again, and is probably around 2003 or beyond," says Leftwich. Phase 2 will see aircraft using ADS to transmit position reports automatically at a faster, and constant rate, allowing extended use of 92km minimum separation in-trail.
With so many plans in the works, it seems the FAA is about to put its money where its mouth is as far as Pacific FANS-1 is concerned.
Source: Flight International
