China faces a massive bill upgrading ATC leverage. It is now looking to CNS/ATM to provide a more affordable solution.
Paul Lewis/SINGAPORE
China represents one of the fastest-growing air-transport markets in the world and, given the country's large, rapidly prospering, population, it has the potential for even greater expansion in the future. With infrastructure development struggling to keep pace with growth, China has been forced for the last two years to apply the brakes. Attention is now turning to the satellite-based communications, navigation and surveillance/air-traffic-management (CNS/ATM) system, which China hopes will provide it with a great leap forward.
The Civil Aviation Administration of China (CAAC) has been involved with the International Civil Aviation Organisation's (ICAO) CNS/ATM initiative from an early stage. It was a founding member of the Pacific Engineering Trials and an active participant in ICAO's Asia/Pacific Air Navigation Planning and Implementation Regional Group.
China formally endorsed the adoption of CNS/ATM at ICAO's 31st Assembly. Its policy broadly calls for the use of a range of systems, including automatic dependence surveillance (ADS), the global-navigation satellite system for en route navigation, non-precision, and possibly Category I, approaches and satellite communications for voice and radar data communication, supplemented by VHF.
Within the CAAC's Air Traffic Management Bureau, a CNS/ATM steering committee, implementation office and advisory group have all now been established. China has not yet committed itself to a definitive timetable, but a more detailed implementation programme is being drawn up, says the authority's CNS/ATM division director Lu Xiaoping.
The CAAC has announced that it is to spend 6 billion yuan ($722 million) on improving and updating China's air-traffic-control (ATC) system, as part of the ninth five-year plan through to 2000. The budget includes $53 million in kick-start funding for mid-term CNS/ATM system development.
A Booz Allen & Hamilton study, commissioned by Rockwell and released in March, estimates that a new conventional ATC system will cost China $1 billion and will still fall short of meeting even the most pessimistic forecasts in air-traffic growth over the next 20 years. A CNS/ATM system, by comparison, would double capacity and lower life-cycle cost, generating $2.7 billion in additional revenue.
CUMULATIVE SAVINGS
The report claims further that the system would provide Chinese airlines with cumulative saving of more than $33 billion in fuel, more than offsetting the projected $500 million cost of upgrading and maintaining CNS/ATM avionics by 2015. It estimates that, for the same period, revenue from CNS/ATM over-flight user fees will be almost twice that of a ground-based system, and more than sufficient to finance the new satellite-based system.
An immediate switch from a terrestrial system to CNS/ATM is not as straightforward, as the Booz Allen & Hamilton report might suggest, however. By far the heaviest concentration of air movements in China is focused on the so-called "golden triangle", or eastern trunk routes linking Chinese capital Beijing with Guangzhou and Shanghai.
"The biggest volume of traffic is in the golden triangle, and the only way of coping is to develop conventional radar systems and start to move from a procedural environment-to providing full ATC in a radar environment," says International Air Transport Association (IATA) regional technical director Anthony Laven.
Chinese radar coverage is now providing aircraft with a 10min separation, and it is hoped with enhancements to reduce this to 32km (17nm), or possibly 8km. "CNS/ATM is not going to do anything immediately for ATC, because the best we could get at the moment is 30 miles [48km] in trail," points out Laven.
While some argue that there is an interim role for ADS, in a high-density environment, as a backup for secondary surveillance radar (SSR), most agree that its more immediate application is in under-developed western China. Raytheon, as a result, recently staged some ADS trials in China, in conjunction with Air China, Boeing, the CAAC, SITA, and United Airlines.
Trials began in March and included an experimental datalink, a United Boeing 747-400 equipped with a FANS-1 package, and an Air China Boeing 737-300 fitted with a global-positioning system (GPS) and ADS-compatible avionics. Controllers at Beijing Capital Airport used VHF and satellite communications to connect with the two aircraft, with the help of SITA's X.25 link-up to a satellite ground station.
A Raytheon Autotrac workstation was used to track the Air China 737 on domestic routes and United's 747 overflights from Chicago to Hong Kong. "We established the first contact with the aircraft crossing the Russian/ Chinese border and then followed it all the way across China into Hong Kong," says Raytheon project manager Dan Busse.
Follow-up trials in June added radar data to the ADS display by integrating the system with a Raytheon solid-state L-band primary-surveillance radar and Cossor monopulse SSR in use at Beijing. Raytheon claims that this was the first time that use of the system had been extended to a multi-sensor ADS/radar environment.
SIMULATOR ACCESS
Controller-pilot datalink-communications (CPDLC) system were added in October, as part of a third and final phase of trials. Beijing controllers used the system to send digital messages to change the altitude and direction of the aircraft. The trials were also extended to a FANS-1-equipped Cathay Pacific Airways 747-400 operating from Hong Kong.
"China's real focus and interest is on a domestic air infrastructure. They were particularly interested in the 737 test aircraft because one of their visions is to use it [the infrastructure] for dynamic routing within China. They are now going to collect their experiences and try to establish a prototype ADS route," says Busse.
Foreign-airline involvement is primarily aimed at, using CNS/ATM to open up faster new routes from western and northern China to Europe and North America. One proposed new European route being actively considered as part of the ICAO TREAT initiative, runs north from Bangkok and north across China, via Urumqi. The route avoids the congested corridor over Calcutta and would offer a 10-15min time saving.
"What we're looking at with the Chinese and Russians is the ability to develop a route though airspace which can only be supported by CNS/ ATM," reveals Laven. He goes on to say that the route is equal to, if not better than, the current routes over the Indian sub-continent, at most times of the year.
The use of CNS/ATM could also open more direct routes from New York to Hong Kong, making non-stop flights commercially feasible for the first time. Other routes being looked at by IATA and ICAO are from New York to Beijing and Shanghai. Before any of this can happen, the CAAC must install suitable ADS workstations, in either Chengdu or Urumqi, find the necessary skilled controllers and, probably the most difficult of all, persuade the air force to open up more airspace.
The CNS/ATM concept has already attracted the interest of China's Committee for Science Technology and Industry for National Defence (COSTIND). It was at the urging of COSTIND, together with the CAAC, that Rockwell's Communications System division in March staged its own technology demonstration at Xian's Xianyang Airport, 800km southwest of Beijing.
One of its principal aims was to show that elements of CNS/ATM can be integrated with existing systems. The main components consisted of two Chinese Cessna Citation II business jets, fitted with antennas and Rockwell avionics equipment pallets, a Northrop Grumman ADS workstation, a Collins DASA differential GPS (DGPS) ground-station and an airport surface-traffic-surveillance system. Rockwell equipped one of the Citations with satellite communications to provide constant tracking of the aircraft, via SITA, over a 1,700km-long flight to Urumqi. A high-frequency (HF) datalink was also used to report the aircraft's position to an existing operational ground station. "We stuck a datalink on the front end of the radio and it worked. You don't need to throw away everything you have," suggests Rockwell ATM system director Mike Ball.
SATELLITE COMMUNICATIONS
Retaining HF would appear to some to run contrary to the whole concept of a future space-based CNS/ATM system. While admitting that satellite communications "-makes a lot of sense", Ball adds that China operates a large number of HF-equipped aircraft. With new digital signal-processing technology, there is no reason why they could not remain in service for many years to come.
The second Citation was fitted with a VHF datalink and a GPS receiver to demonstrate Category I approaches to Xianyang under digital GPS (DGPS) guidance. According to Rockwell, the aircraft on approach was able to acquire a DGPS correction within 190km of the airport, and on outbound flights a link up to 260km away was maintained.
"If China is going to put more and more services into small airports, then GPS will provide a good means of avoiding the large capital investments in ground aids and the long time it will take to put them in position," says Laven. How quickly China starts to implement CNS/ ATM still remains unclear. The recent Beijing and Xian trials have certainly helped to elevate discussions within the CAAC from a theoretical to a practical level.
Source: Flight International
